Friday, December 27, 2019

How did the universe begin?

The year is almost over and a new one about to begin. So today I want to talk about the beginning of everything, the whole universe. What do scientists think how it all started?


We know that the universe expands, and as the universe expands, matter and energy in it dilutes. So when the universe was younger, matter and energy was much denser. Because it was denser, it had a higher temperature. And a higher temperature means that on the average particles collided at higher energies.

Now you can ask, what do we know about particles colliding at high energies? Well, the highest collision energies between particles that we have experimentally tested are those produced at the Large Hadron Collider. These are energies about a Tera-electron Volt or TeV for short, which, if you convert it into a temperature, comes out to be 1016 Kelvin. In words that’s ten million billion Kelvin which sounds awkward and is the reason no one quotes such temperatures in Kelvin.

So, up to a temperature of about a TeV, we understand the physics of the early universe and we can reliably tell what happened. Before that, we have only speculation.

The simplest way to speculate about the early universe is just to extrapolate the known theories back to even higher temperatures, assuming that the theories do not change. What happens then is that you eventually reach energy densities so high that the quantum fluctuations of space and time become relevant. To calculate what happens then, we would need a theory of quantum gravity, which we do not have. So, in brief, the scientific answer is that we have no idea how the universe began.

But that’s a boring answer and one you cannot publish, so it’s not how the currently most popular theories for the beginning of the universe work. The currently most popular theories assume that the electromagnetic interaction must have been unified with the strong and the weak nuclear force at high energies. They also assume that an additional field exists, which is the so-called inflaton field.

The purpose of the inflaton is to cause the universe to expand very rapidly early on, in a period which is called “inflation”. The inflaton field then has to create all the other matter in the universe and basically disappear because we don’t see it today. In these theories, our universe was born from a quantum fluctuation of the inflaton field and this birth event is called the “Big Bang”.

Actually, if you believe this idea, the quantum fluctuations still go on outside of our universe, so there are constantly other universes being created.

How scientific is this idea? Well, we have zero evidence that the forces were ever unified and have equally good evidence, namely none, that the inflaton field exists. The idea that the early universe underwent a phase of rapid expansion fits to some data, but the evidence is not overwhelming, and in any case, what the cause of this rapid expansion would have been – an inflaton field or something else – the data don’t tell us.

So that the universe began from a quantum fluctuations is one story. Another story has it that the universe was not born once but is born over and over again in what is called a “cyclic” model. In cyclic models, the Big Bang is replaced by an infinite sequence of Big Bounces.

There are several types of cyclic models. One is called the Ekpyrotic Universe. The idea of the Ekpyrotic Universe was originally borrowed from string theory and had it that higher-dimensional membranes collided and our universe was created from that collision.

Another idea of a cyclic universe is due to Roger Penrose and is called Conformal Cyclic Cosmology. Penrose’s idea is basically that when the universe gets very old, it loses all sense of scale, so really there is no point in distinguishing the large from the small anymore, and you can then glue together the end of one universe with the beginning of a new one.

Yet another theory has it that new universes are born inside black holes. You can speculate about this because no one has any idea what goes on inside black holes anyway.

An idea that sounds similar but is actually very different is that the universe started from a black hole in 4 dimensions of space. This is a speculation that was put forward by Niayesh Afshordi some years ago.

 Then there is the possibility that the universe didn’t really “begin” but that before a certain time there was only space without any time. This is called the “no-boundary proposal” and it goes back to Jim Hartle and Stephen Hawking. A very similar disappearance of time was more recently found in calculations based on loop quantum cosmology where the researchers referred to it as “Asymptotic Silence”.

Then we have String Gas Cosmology, in which the early universe lingered in an almost steady state for an infinite amount of time before beginning to expand, and then there is the so-called Unicorn Cosmology, according to which our universe grew out of unicorn shit. Nah, I made this one up.

So, as you see, physicists have many ideas about how the universe began. The trouble is that not a single one of those ideas is backed up by evidence. And they may never be backed up by evidence, because the further back in time you try to look, the fewer data we have. While some of those speculations for the early universe result in predictions, confirming those predictions would not allow us to conclude that the theory must have been correct because there are many different theories that could give rise to the same prediction.

This is a way in which our scientific endeavors are fundamentally limited. Physicists may simply have produced a lot of mathematical stories about how it all began, but these aren’t any better than traditional tales of creation.

367 comments:

  1. Surely the scientific theories have a non-zero chance of being correct, unlike the traditional tales of creation.

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    Replies
    1. The chance is almost zero in the mathematical sense because there are infinitely many alternatives.

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    2. Sabine Hossenfelder1:09 AM, December 28, 2019

      "The chance is almost zero"
      If the theories were chosen at random, but they aren't. Hawking's theory and Turok's theory are based on quantum and GR theory which is known to apply to the universe, and are attempts to extrapolate back from an understood point. I think the probability of these theories being correct is unknown, though granted there is the sense that moving too far away from empirical evidence won't lead to a correct theory.

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    3. The current ways that theories are being chosen are equally useful as random choice. Read my book if you still don't get it.

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    4. Sabine Hossenfelder2:04 AM, December 28, 2019

      Hawking's and Turok's theories were not chosen at random. To claim that the probability that they are correct is almost zero is to suggest you have constructed a precise mathematical Lebesgue measure over the correctness of these kind of theories, which is impossible. This is not to say that your blog post is not informative and interesting in general, though.

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    5. Steven,

      I didn't say they were chosen at random. Do you have trouble reading? There are infinitely many theories that give you the same observational consequences, hence they are all equally "correct" scientifically. I don't need a measure for correctness if I am only talking about one type of correctness which is correctness.

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    6. Not that it's a major point...
      Originally you said that the chances of the theories listed in the post being correct as opposed to incorrect were almost zero:

      "PaulTopping1:37 PM, December 27, 2019
      Surely the scientific theories have a non-zero chance of being correct,"

      "Sabine Hossenfelder1:09 AM, December 28, 2019
      The chance is almost zero in the mathematical sense because there are infinitely many alternatives. "

      But now you are saying that among correct theories there are infinitely many theories matching observations. I see how this second comment is correct but not the first one.

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  2. I am surprised you haven't seen the evidence Halton Arp uncovered in his book Seeing Red. He was a student of Hubble. Through radio telescopes he observed that highly red-shifted quasars are connected to low-redshift galaxies. This suggests that the whole idea that the universe is expanding is false, and should be abandoned. Of course he was punished in the usual way - telescope time taken away, journals refused to publish him, etc.

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    Replies
    1. Indeed. If the astronomical redshift is originated by the vacuum absorption of dark matter black holes small and large. Halton Arp could be right.

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    2. I am surprised that this "Arp" myth is still around.

      Are you, Arvind Damarla, or you Leo Vuyk, familiar with SDSS? Do you know how much deeper (fainter objects detected) and at better resolution SDSS is than anything Arp ever had to work with? How many thousands of times more spectra - of galaxies, AGNs, etc - SDSS has than Arp could ever have dreamed of?

      Did you also know that all the SDSS data - including all the raw FITS - is available, for free? All you need is a good internet connection!

      If you really think Arp was onto something, why not do your own analyses of SDSS data?

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    3. All of Arp's examples have been shown to be random superpositions by observations at higher resolution.

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    4. @Jean Tate,

      Do you know how much deeper (fainter objects detected) and at better resolution SDSS is than anything Arp ever had to work with? How many thousands of times more spectra - of galaxies, AGNs, etc - SDSS has than Arp could ever have dreamed of?

      Did you also know that all the SDSS data - including all the raw FITS - is available, for free? All you need is a good internet connection!

      If you really think Arp was onto something, why not do your own analyses of SDSS data?


      So Arvind Damaria mentions Arp's observations and you dismiss them as a "myth" and offer in support of your opinion a series of non sequiturs:

      Sloan Digital Sky Survey! Lots of data! More than Arp had! Available on the internet! Do your own analyses!

      That's pathetic and it does not constitute a scientific argument of any sort. The simple fact is that Arp's model of galaxy formation has far more observational support than whatever variant of the accretion model is currently popular with the purveyors of the big bang creation myth.

      @sir lawrence,

      All of Arp's examples have been shown to be random superpositions by observations at higher resolution.

      Please cite the evidence for that claim. It's not just something you heard back there in graduate school, right?

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    5. @bud rap: I did not dismiss Arp's observations as a myth; they are what they are. And you - and anyone with a good enough internet connection etc - can find them and much more recent observations of the objects Arp reports in his papers.

      "The simple fact is that Arp's model of galaxy formation has far more observational support than whatever variant of the accretion model" Really? I did not know that. Do you have some evidence, such as a relevant paper?

      I'll repeat the last line of my previous post: "If you really think Arp was onto something, why not do your own analyses of SDSS data?"

      Why is this relevant? Because you (and Arvind Damarla, and Leo Vuyk) can now do much more than Arp ever could, in terms of observational data, analysis software, and access to getting your results published.

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    6. @Jean Tate,

      I did not dismiss Arp's observations as a myth...

      Perhaps I just misunderstood this:

      I am surprised that this "Arp" myth is still around.

      Do you have some evidence, such as a relevant paper?

      https://www.amazon.com/Catalogue-Discordant-Redshift-Associations-Halton/dp/0968368999

      I know of no similar body of observational evidence supporting the accretion theory of galaxy formation. If you do, please cite it.

      If you really think Arp was onto something, why not do your own analyses of SDSS data?

      Why don't I do it myself? That's an arrogant answer Jean, and let me explain why.

      Unlike you, I do not get paid to do science, it is simply an avocation of mine. Restricting my comments to the cosmological sciences, what I have found over the years, is that people who are paid scientists, do not conduct themselves as scientists, engaged in an open-ended investigation into the nature of the cosmos. Rather, they behave as a closed society of guild members, sharing a common set of beliefs. Most of their beliefs concerning the nature of physical reality have, on close examination, no empirical (scientific) basis whatsoever.

      The members of this guild appear to busy themselves polishing the chrome on the rusting hulk of their empirically baseless standard model while obscuring its inadequacies with thick layers of mathematical formalisms. When someone like me complains of the scientific shortcomings of the output of these efforts, we are advised to make our own model, if we don't like the one on offer.

      That is as if I'd paid a mechanic to do some repairs on my car, and finding the repairs inadequate and complaining, the mechanic advised me to fix it myself, if I didn't like his work. Even if I could, there is no reason I should accept that advice as anything other than a sad reflection on the mechanic's professional competence.

      As far as Arp's observations and theory of galactic formation go, both have been actively suppressed from their inception, on the basis of spurious statistical arguments, by the astronomical community of which Arp was a well established member. This all began at the onset of the new dark age, when astronomers commenced to seeing things that aren't there, and not seeing things that are there. And so, modern cosmology is an unscientific mess.

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    7. @bud rap: the "Arp myth" is, in a simple form, that Arp discovered good evidence for "discordant redshifts". Another version includes something like "he was blacklisted/prevented from doing further observations because his hypothesis was unpopular among mainstream astronomers". The former is easily demolished (and explored in quite a few papers); the latter relies almost entirely on Arp's own views. There is some material in the public domain, from astronomers at the time, that Arp didn't get much more telescope time for the mundane reason that his proposals ranked lower than his competitors'.

      Re: "The simple fact is that Arp's model of galaxy formation has far more observational support" and https://www.amazon.com/Catalogue-Discordant-Redshift-Associations-Halton/dp/0968368999: sadly, I don't think you're joking. But perhaps I misunderstand; what, succinctly, to you think "Arp's model of galaxy formation" is?

      Re: "Unlike you, I do not get paid to do science, it is simply an avocation of mine. " Perhaps you could let me know who is paying me to do science? I think I may be owed some back-pay! Seriously: how do you know if I get paid anything?

      And if I am not paid, by anyone, then the rest of your, um, rant fails, doesn't it?

      Anyway, it's beside the point: there is a vast treasure trove of astronomical data, available to anyone (with a sufficient internet connection), for free. It is vastly richer than anything Arp worked with; indeed, it is now surely far beyond even his dreams. Likewise, for extremely modest cost (likely zero if you're determined), anyone can obtain very sophisticated analysis tools, e.g. DS9. Alternatively, anyone can learn Python or R and develop or modify such tools. For free. Again, this is waaay beyond what Arp had, or could even dream of.

      Re: "As far as Arp's observations and theory of galactic formation go, both have been actively suppressed from their inception" You seem to live in a different universe than I do.

      First, every observation Arp made, and subsequently published, is available (just read the papers).

      Second, none of Arp's published papers have disappeared from the relevant journals' websites (sadly, some still insist on payment, even for decades-old papers, but there are ways around such paywalls).

      Third, no one stopped Arp from self-publishing, as your link proves. As far as I know, there is nothing in any of the books (with Arp as author) which is not also in one or more of his published papers (and I think all that's in his books was first published in such papers).

      Conclusion: you don't seem to like putting time and effort into learning about public astronomical datasets and/or analyzing them, much less trying to actually write a paper based on such work.

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    8. One more before NYE celebrations: re "The simple fact is that Arp's model of galaxy formation has far more observational support than whatever variant of the accretion model is currently popular with the purveyors of the big bang creation myth." and "I know of no similar body of observational evidence supporting the accretion theory of galaxy formation. If you do, please cite it."

      A search for "galaxy formation" in the Titles in the astro-ph part of arXiv turns up hundreds of hits, dozens in 2019 alone. Here is one, chosen at random: "The Evolution of Sizes and Specific Angular Momenta in Hierarchical Models of Galaxy Formation and Evolution" (Zoldan+ 2019, https://arxiv.org/abs/1902.10724). I do not know if this fits either of your categories ("accretion theory", "accretion model"), but I guess that it likely does. Nor do I know what you consider to be a relevant "body of observational evidence", for this topic.

      Perhaps you could tell us all?

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    9. Jean Tate is very arrogant and does not tell the truth on how
      Halton Arp was treated by the astronomy community.

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    10. jvs wrote:
      >Jean Tate is very arrogant and does not tell the truth on how Halton Arp was treated by the astronomy community.

      Perhaps you could elaborate?

      Look: those of us who actually do know a great deal about science inevitably come across as "arrogant" because contemporary social mores maintain that all ideas, all points of view, no matter how loopy, are equally valid and important.

      Science is just the opposite.

      Science ruthlessly destroys ideas that do not stand up to rigorous testing by observation and by comparison to complementary knowledge we already have of Nature.

      You believe in "Pyramid Power"? Or astrology? Or Young-Earth Creationism? You are free to do that, but if you associate with scientists and insist on bringing your ideas to their attention, you need to understand that they are free to ridicule your ideas.

      You don't like that? Stay away from scientists!

      There is substantial evidence for the Big Bang besides the cosmic redshift relation: the CMB, the initial elemental composition after the Big Bang, the change in elemental composition of stars over time, the age of the oldest stars, etc. And in any plausible theory of gravity, including just plain old Newtonian gravity, a static universe is not stable: the universe has to be either contracting or expanding: and almost no one thinks it is contracting.

      In short, Arp had a huge uphill battle, for very good reason. And then there is the huge statistical problem: statistically, he was going to find some sources that, by statistical accident, were in the same line of sight but not really associated at all. He had a huge burden to convince the scientific community that he had correctly taken into account all these false positives. (Jean Tate knows much more about all this than I do.)

      Can you see why lots of scientists were not inclined to take him seriously? I didn't.

      Just on the face of it, can you see that Arp was probably wrong?

      Scientists can be just as nasty as anyone else (I can think of several specific examples). Maybe the astronomical community was unkind personally to Arp. But to convince us that it made a difference, that there is any significant chance that he was right, you yourself have a huge hill to climb.

      Just accusing Jean of being arrogant does not cut it. All you show is that you yourself reject the ethos of science, the practice of science that has brought us everything from antibiotics to cell phones.

      (And, for the record, Jean's behavior here has been far less arrogant than most scientists I have known and indeed most adult professionals I have known in all sorts of fields, from law and medicine to business management and education.)

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    11. jvs,

      If you think what I wrote about how "Halton Arp was treated by the astronomy community" is inaccurate, please clarify. I would be particularly interested to read what contemporaries of Arp have to say (for the record, I personally had nothing to do with Arp beyond reading some of his papers, often long after they were published).

      But, like bud rap, I think you are missing the point: the data and tools to continue Arp's work are widely, and freely, available. This is far more important than how Arp may, or may not, have been treated by his colleagues, in the 1960s and beyond.

      So, jvs, why not make a contribution to science, by downloading some astronomical data and analyzing it (perhaps using Python code you write yourself?). Following the techniques Arp describes in his papers. Then write up what you found and get it published!

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    12. Pardon me for injecting, but I've been through this Arp business in some detail, including many papers and both his books (Seeing Red and Quasars, Redshifts, and Controversies), so I feel I need to clear up a couple of issues..

      1) "All of Arp's examples have been shown to be random superpositions by observations at higher resolution."

      This is simply not so. The case of NGC 7603 alone is enough to contradict this statement. There is no need to multiply examples. Forget Arp, see the work of Lopez-Corredoira.

      2) "[Arp's work] suggests that the whole idea that the universe is expanding is false, and should be abandoned." This is totally false and was never claimed by anyone with a serious understanding of the matter, particularly not Arp. The cosmic redshift is very real, but like all redshift, it is agnostic. Any other sources of redshift will add/subtract from it. The crucial point is to explain the high redshift of quasars, not to propose an alternative cosmology. Indeed, from my perspective as someone who doesn't have a high opinion of any cosmology - a Disneyist if you will - the intrusion of cosmology wars into this fascinating problem is distressing. Let's stick to astrophysics, please, and leave religion to the religious.

      3) "Because SDSS" This doesn't help with the main problem, which is to identify quasar candidates and get their spectra. Arp didn't have a theory as such, he had a mechanism, that quasars are a new state of matter that originates in active galactic nuclei, and which by unknown processes in those nuclei, are axially ejected at high speed, perhaps pair-wise across the nucleus, followed by their evolution into "normal" matter with a normal kinetic/cosmic redshift.

      4) "Arp was treated fairly." This is a real howler. He was essentially ostracized. Lopez-Corredoira has more or less suffered the same fate. There is no doubt about this.

      5) So what could cause intrinsic redshift? Well, the most obvious thing is a so-far undemonstrated connection between the two long-range classical interactions, gravitation and electromagnetism. An essential unification would imply that not only does an electromagnetic field generate a gravitational field, but also the reverse, so that extremely dense and exotic states of matter could have their own characteristic electromagnetic signature. To ignore the compelling evidence Arp collected regarding association of low- and high-redshift objects cuts us off from what could be extremely important clues about the nature of gravitation and its relation to electromagnetism. This is contrary to the spirit of astrophysics. The cosmology disease threatens to kill the patient by diverting attention from the really important observations that should be made, but for which Lopez-Corredoira could not get telescope time. (He made do with inferior instruments for his study of NGC 7603.)

      -drl

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    13. @Jean More papers are not needed. Telescope time is needed. There is a pair of Siamese twin LSB galaxies SE of the Sombrero Galaxy in Virgo (Messier 104) that are glowing like mad in the infrared. They are comparable in brightness to the galaxy itself. See this image..

      https://www.jpl.nasa.gov/spaceimages/details.php?id=PIA07899

      I cannot even find a catalog entry for this object. On high res images, a third triplet can be see that is deeply redshifted. This extraordinary object needs to be closely studied by the very best instruments - but try to get time to do it. Instead, Hubble's precious lifespan is wasted on vacuous "student projects". Such things are intensely frustrating.

      BTW if anyone wants a good PhD topic - identify all the LSB galaxies just in the one high-res visual light image of M-104 that are putative spirals, estimate their eccentricities, and see if they follow a random distribution of orientations. You will find that they don't, and that the objects are likely cigar-shaped and not edge-on spirals. But that's another ignored topic. People prefer jawing and pontificating to looking and thinking.

      -drl

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    14. "But, like bud rap, I think you are missing the point: the data and tools to continue Arp's work are widely, and freely, available." False - what is needed is big telescope time and lots of it. Try to get some that doesn't purport to be a dark matter/energy study or yet another vacuous survey. The telescope time is doled out to support the existing paradigms, not to just do some hard looking. It is groupthink, and it is a plague.

      -drl

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  3. Why is always big bang just a one big time event? Why there aren't many other smaller ones hapenning, scattered across universe, both in time and place?

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    1. If there were, and if these mini-bangs were in the observable universe, we'd have seen them by now.

      In cosmology, observation is king, queen, and the whole nine yards! :)

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    2. @JT I am reading the same cosmology as you, and I see the totally opposite behavior. Observations will be resolutely bent and mangled to fit theories. The observations are secondary to the theory.

      -drl

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  4. Space and time are metaphysical quantities that can be cast as relative parameters for the purpose of doing physics.

    The relatively of space and time actually speaks against the current rage for their " thingification".

    To say that we 'know' the universe is expanding and thus must of had a beginning seems rash. Rather, one should say this is an interpretation of certain data within the framework of a currently popular (though problematic!) theory. You actually suggest this more cautious approach at the end of your most excellent essay !

    The universe could be infinite and eternal. A more likely, but still mind boggling, idea.

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  5. How does second law of thermodynamics look like in cyclic models?

    In Big Bang everything is localized so entropy is low.
    But shouldn't it also apply to its symmetric sibling: Big Crunch, e.g. assuming that our universe will finally collapse, or that our Big Bang was preceded by Big Crunch - shouldn't Big Bounce be (time/CPT symmetric?) local entropy minimum?

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    1. Jarek,

      It is a big problem, long recognized by physicists.

      Personally, I think it is a killer for a cyclic universe theory.

      On the other hand, neither I nor anyone else knows why the universe started in a very low entropy state.

      There is something really big here that we are all missing. How it plays out is anyone's guess.

      All the best,

      Dave

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    2. Dave,

      In smaller volume you need less information to specify position - entropy should be lower. Isn't such localization argument sufficient to explain entropy being minimal in Big Bang?

      And this question is not only limited to cyclic models - there is still a possibility that our universe will finally collapse.
      Such hypothetical Big Crunch would be again localized - shouldn't it also have low entropy?
      ... and doesn't energy conservation suggest that such collapse should not just disappear, but be a Big Bounce instead - is there any argument for our universe indeed disappearing as a result of collapse?

      While this question sounds abstract, cosmological, it also regards understanding a supposed conflict between:
      - fundamental theories being time/CPT symmetric: QFT, GR, QM unitary evolution,
      - effective theories being asymmetric: thermodynamics, statistical physics.

      It is common to project this asymmetry to fundamental physics, but should we really do it?
      I recommend looking at derivations of asymmetry in symmetric models, what seems a nonsense as we could use the symmetry first and prove the opposite - contradiction.

      Such "proofs" e.g. Boltzmann H-theorem (
      https://en.wikipedia.org/wiki/H-theorem ) need to use subtle assumption "Stosszahlansatz": which erases detailed information, replacing it with smeared statistical picture - what allows to prove entropy growth.
      But not erasing this information, such systems can instead e.g. have cyclic entropy evolution, like simple educative Kac ring model:
      http://www.maths.usyd.edu.au/u/gottwald/preprints/kac-ring.pdf

      So maybe 2nd law does not contradict cyclic models, only we humans should be more careful with enforcing consequences of effective models.

      All the best,
      Jarek

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    3. Jarek Duda wrote to me:
      >In smaller volume you need less information to specify position - entropy should be lower. Isn't such localization argument sufficient to explain entropy being minimal in Big Bang?

      Good question: I've thought about this, but I do not know the answer. On the face of it, yes, but...

      There are some adiabatic theorems about quantum states that may be relevant here. At least in the case of the CMB, I do not think the expansion has increased the entropy (of course, it got cooler, which has an opposing effect). There are also some arcane issues involving renormalization: do you scale your renormalizations scale along with the expansion of the universe (probably not, but the answer is not clear to me)?

      Anyway, my impression is that this will not solve the problem, but I do not really know: in any case, the Big Crunch should not suffice to completely undo any non-cosmological increases in entropy. (As I recall, Hawking once thought the point you raise was correct but later changed his mind.)

      Perhaps Sabine or Jean Tate or someone else here knows the current state of this issue?

      Jared also asked:
      >and doesn't energy conservation suggest that such collapse should not just disappear, but be a Big Bounce instead - is there any argument for our universe indeed disappearing as a result of collapse?

      I think the answer is "quantum effects": i.e., no one knows.

      Jared also said:
      >Such "proofs" e.g. Boltzmann H-theorem (
      https://en.wikipedia.org/wiki/H-theorem ) need to use subtle assumption...

      Yeah, the H-theorem seems obviously true, but seems to lead to absurd conclusions, such as Nick Bostrom's (and others') "Boltzmann brains" argument.

      One important point here is that you have to be careful with gravity, because, uniquely among the four fundamental forces, gravity tends to make the universe lumpier. But again this is not something I am an expert on.

      My own conclusion is that we really, really do not understand the nature of the "arrow of time": in that conclusion, at least, I am in good company going back over fifteen hundred years (I'm referring to Augustine of Hippo).

      All the best,

      Dave

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    4. Derivation of Boltzmann H-theorem erases information in its stosszahlansatz assumption - required to break the symmetry.
      But can we be certain that this assumption is always true?

      While our human intuition requires such time arrow symmetry breaking, maybe let's try to be more careful for a moment.
      For example Lagrangian formalism (we use from QFT to GR) has basically two mathematically equivalent formulations:
      1) Euler-Lagrange evolution forward in time,
      2) The least action principle, which is time-symmetric.

      There is by default used 1) as the intuition how the history of the Universe is chosen.
      But what if it was originally chosen in a symmetric way like the least action principle 2)?
      What arguments for 1) or 2) are there?

      In 2) case, fixing state in the past e.g. in Big Bang, and future e.g. in Big Crunch, the history of universe was chosen as the action optimizing between them, hypothetical Big Crunch should be symmetric sibling of Big Bang.
      Then switching to Euler-Largange evolution, its state was already chosen also accordingly to all future measurements - as in superdeterminism.

      All the best,
      Jarek

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    5. Jarek asked:
      >While our human intuition requires such time arrow symmetry breaking, maybe let's try to be more careful for a moment.
      ...
      >In [the least-action formulation] case, fixing state in the past e.g. in Big Bang, and future e.g. in Big Crunch, the history of universe was chosen as the action optimizing between them, hypothetical Big Crunch should be symmetric sibling of Big Bang.
      >Then switching to Euler-Largange evolution, its state was already chosen also accordingly to all future measurements - as in superdeterminism.

      Yeah, it's true that in classical mechanics you can usually specify the initial and final states rather than the initial state and initial velocity (I say "usually" because there can be occasional problems: try to set initial and final states that violate the periodicity constraint for the simple harmonic oscillator, and bad things happen!).

      Have you seen the book Time's Arrow and Archimedes' Point by the philosopher Huw Price? Like most physicists, I am often derisive towards philosophers, but Price is very bright and takes the physics seriously. He argues that the sort of approach you suggest could solve various problems (including the measurement problem in QM).

      I take the idea seriously, but there has been a real problem in implementing it in QM: basically, in classical mechanics, you can specify two sets of conditions, initial position and velocity, or, alternatively, initial position and final position, because of the fact that the equations of motion in classical mechanics are second-order differential equations.

      But, the Schrödinger equation in quantum mechanics is first-order: you do not have the freedom to specify both initial and final conditions. Of course, that has not kept people (including me) from trying: for example, maybe somehow you can take the initial wave function and the final wave function and use both to describe what is happening?

      As far as I know, no one has ever been able to make it work.

      I myself actually invented a pseudo-Bohmian mechanics that is second-order: maybe it will work there? Well.. not yet.

      Another place I have looked that may relate to this is the work of the late Asher Peres (his book, Quantum Theory: Concepts and Methods and his papers on the arXiv). I've never been able to figure out if most of his work is meaningful or if it is just suggestive calculations without any real physical content. (Peres was not a fool: as far as I can see, his calculations were correct, but I am not at all sure what those calculations actually mean!)

      So, the answer to your question is "Well, maybe..."

      Both physicists and philosophers have thought about this, and it seems to a lot of us that something like this should work. This is related to the issue that Terry Bollinger raised on another thread about taking a "block-universe" perspective and "annealing" the block universe.

      Both ideas seem promising to me, but none of us have been able to make them work in detail.

      Of course, it is always possible that some young physicist will come along in a couple years and show us the "obvious" trick that we all missed that will show how it should be done!

      All the best,

      Dave

      P.S. I would not however recommend this sort of thing for a Ph.D. thesis project: too likely to fail and thereby drag out grad school interminably!

      Delete
    6. Lagrangian formalism is not only classical mechanics - it is generalized further to classical field theories like EM or GR, and then further to QFT like QED or QCD.
      While we are used to Feynman diagrams, it is perturbative approximation, and there is also considered non-perturbative e.g. lattice QCD.

      Anyway, all of them (CM, EM, GR, QED, QCD) are time or CPT symmetric.
      In contrast, we enforce our asymmetric intuition that physics solves them in asymmetric way like Euler-Lagrange.

      But what if physics solves such symmetric theories in symmetric way?
      While mathematically there can be equivalence like between Euler-Lagrange and least action principle, there is subtle difference between finding solution using one of them - only symmetric ways take both past and future into consideration, like in superdeterminism.

      There are a few ways to solve them in symmetric way, e.g.:
      1) the least action principle,
      2) ensembles of (Feynman) paths, diagrams - it is a symmetric way e.g. if they go from minus to plus infinity,
      3) TSVF: translating them into propagators and seeing the current moment as a result of meeting of such two propagators: from minus and plus infinity - https://en.wikipedia.org/wiki/Two-state_vector_formalism

      I haven't read Huw Price, but am in contact with a few physicists agreeing that problems with understanding QM like Bell theorem come from being fixed on asymmetric way, and they disappear if using symmetric as above (I can add you to our forum if you want?).

      Regarding Schrödinger equation, it can be made symmetric through Feynman path ensembles, TSVF.
      Wavefunction collapse is a result of interaction with environment, e.g. "excited atom <-> deexcited atom + photon" is reversible.

      And see Maximal Entropy Random Walk - just trivial uniform path ensemble, already getting Anderson localization, Born rules - which can be used for Bell violation construction.
      E.g. for dynamics in [0,1] range, diffusion/chaos gives uniform rho=1 stationary probability distribution, but QM says rho~sin^2. Uniform distribution of paths in one direction gives rho~sin, of complete paths rho~sin^2 as we have to multiply both.

      All the best,
      Jarek

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    7. Jarek wrote to me:
      >Lagrangian formalism is not only classical mechanics - it is generalized further to classical field theories like EM or GR, and then further to QFT like QED or QCD.

      Yeah, but it is used differently in the classical theories vs. the quantum theories.

      In the classical theories, you can minimize the action between two specified end states (initial and final). In the quantum theories, you sum over all possible paths with weighting factors that are the imaginary exponential for the action for each path.

      Look at a simple case such as the (non-relativistic) simple harmonic oscillator in quantum mechanics. Start in. let's say, the first excited energy level as the initial state. You now cannot freely choose the final state: it is completely determined by the initial state. (I use the simple harmonic oscillator because, after all, that is basically how we analyze fields in QFT: the SHO is everywhere!)

      One way of thinking of QM is that we slice the number of independent variables in two: instead of both position and momentum or position and velocity, you must choose only one of the pair -- if you choose position, then momentum is out of your control (Fourier transform, uncertainty principle, and all that).

      You only have half as many independent variables in QM as in the corresponding classical theories. So you cannot choose both the initial wave function and the final wave function.

      Of course, that has not prevented people (including me) from trying: The TSVF is what I referred to earlier as the failed attempt by many of us physicists. It's possible that someone has made some breakthrough on this of which I am not aware, but everything I know about this, including my own attempts, simply do not really work.

      I agree with you that intuitively it feels as if something like TSVF should be possible. And, yes, stuff like this really is possible in Brownian motion (e.g., the famous "Brownina bridge"), and diffusion is, after all, just a factor of "i" away from the Schrödinger equation! And it would presumably be a successful example of the "superdeterminism" that Sabine is looking for.

      It would be so nice! But, as far as I know, no one has been able to make it work.

      Dave

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    8. The least action principle allows to imagine e.g. spacetime as block universe: symmetric "4D jello" minimizing tension, what translates to equilibrium condition for 4D intrinsic curvature in Einstein's equation.

      But indeed while going from classical to quantum field theories, the least action principle is replaced with path ensemble - does it break time symmetry?

      Assuming physics finds solution using path ensembles, when is the start and end of these paths?
      It needs emphasizing two points in time - mathematically natural choice is minus plus infinity, we could also choose Big Bang, Bit Crunch - what other times could we emphasize this way?

      Assuming e.g. paths physics use in ensembles are from minus to plus infinity (from what we can imply TSVF), don't we have superdetermism as such ensemble also includes all future measurements?

      Regarding excited state of harmonic oscillator (or atom), remember that its deexcitation produces energy difference to environment e.g. in form of photon - such process is reversible, but for such reversed process you need to provide the photon.
      Which processes are not time symmetric?

      Regarding QM working on position xor momentum, doesn't it resemble the difference between Euler-Lagrange and the least action principle?
      The former works on value and first derivative, the latter only on values - but in two moments of time ... like path ensembles.

      All the best,
      Jarek

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    9. Jarek Duda wrote to me:
      >But indeed while going from classical to quantum field theories, the least action principle is replaced with path ensemble - does it break time symmetry?

      No... but you specify fewer degrees of freedom in QM: position space at one point in time, not position and momentum. You can go forward in time OR backward in time in QM, but not both simultaneously, at least no one has made it work (I know some people have published on this, but what they have published seems to amount to "We hope we can make this work someday...").

      Jarek also wrote:
      >Regarding QM working on position xor momentum, doesn't it resemble the difference between Euler-Lagrange and the least action principle?
      >The former works on value and first derivative, the latter only on values - but in two moments of time ... like path ensembles.

      No, you go from Euler-Lagrange to least action by maintaining the same number of boundary conditions: initial position and momentum for the normal equations of motion or initial and final position only for least action. For QM, the wave function over initial position alone is sufficient: there are not enough degrees of freedom to also specify the wave function for the final state.

      At least, no one has ever made it work (again, I know there are publication, but they just do not work).

      Jarek also wrote:
      >Assuming e.g. paths physics use in ensembles are from minus to plus infinity (from what we can imply TSVF), don't we have superdetermism as such ensemble also includes all future measurements?

      No, again the problem is that no one has made TSVF actually work.

      Look: the state of physics nowadays, as Sabine has emphasized, is such that people with possibly interesting but in fact half-baked ideas manage to get them published, at least on the arXiv.

      TSVF is one of those ideas.

      I've fooled around with it as have many other people. The difference is that since I could not get it to actually work, I did not try to squeeze a publication out of my failure. Others, alas, were less restrained.

      If you can point to something I missed where someone successfully worked out TSVF in all its nitty-gritty, gory detail and showed how it provides, in detail, for a realist, superdeterministic theory that explains the QM violation of Bell's inequality... well, great!

      But everything I have seen on it is stuff that is simply "lost in math" or, to steal a phrase from another blogger, "not even wrong."

      Sorry, but the mere fact that so many physicists nowadays write up their failures in order to squeeze out another publication for their CV does not change a failure into a success.

      Of course, if you can point to one single publication (not a maze of mutually cross-referencing papers that promise the sky but go nowhere!) where someone has made it all work, you can prove me wrong.

      Let me make clear: I am not trying to provide a mathematical proof that TSVF cannot work. I am merely noting that it has not worked and trying to offer a suggestive explanation as to why: the Schrödinger equation is first-order and the standard equations for classical mechanics are second-order, and that really does affect how you can set boundary conditions.

      But maybe someone (could even be me!) will figure out a way around this and somehow, someday make something like TSVF work.

      But not, it seems, yet.

      Dave

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    10. If I properly understand, you agree that accepting time/CPT symmetry is a promising direction to save local realism from Bell theorem, the reason for superdeterminism ... but you see it mathematically problematic to consider Feynman path ensembles for paths from minus to plus infinity?

      So maybe let's start with simpler path ensemble: Boltzmann, or even simpler: uniform.
      Here is sketch of derivation for it using simple combinatorics:

      https://en.wikipedia.org/wiki/Maximal_entropy_random_walk#Sketch_of_derivation

      You consider ensemble of paths from t-l to t+l, looking only at situation around time t.
      Then perform l->infinity limit, directly getting Born rules (analogously as in TSVF): rho~psi^2 where psi comes from discrete stationary Schrodinger equation.
      The same is for Boltzmann ensemble, I have also Bell violation construction for such uniform path ensembles - where exactly do you see a problem with taking it to Feynman path ensembles?

      All the best,
      Jarek

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    11. First: you cannot use Grand Canonical Ensemble if there are long ranged forces, eg. gravity.
      Second: gravitational systems tend to collapse, and finally it may seem to single black hole, but there are stable periodic configurations ( we solar system, see KAM theorem) so basically we cannot easily say state with black hole is final state of such systems.
      Third: black hole entropy is maximal one, and you cannot make it bigger.
      From above it may follow that statement that at Big bang universe was at low entropy is false

      Delete
    12. Jarek wrote to me:
      >If I properly understand, you agree that accepting time/CPT symmetry is a promising direction to save local realism from Bell theorem, the reason for superdeterminism...

      Well, I think you are trying to work at a more abstract level than I am.

      First, in principle you can do the same thing with the Schrödinger equation and with wave functions as you can do with Feynman path integrals (for QFT you may have to make things finite by putting it in a box and having a cutoff, if necessary a lattice).

      I've found, from experience, that people who insist on working in terms of the path integral are more likely to fly off into meaningless flights of fancy; whereas the Schrödinger equation and wave functions force one to be a bit more definite and grounded.

      There is a reason that Bohmian mechanics came from the Schrödinger equation. For all its negative aspects, Bohmian mechanics was a real achievement: remember, Johnny von Neumann had “proved” it was impossible!

      And, again from experience, I have found that trying to work out something like TSVF from the Schrödinger equation and the wave function runs into the sorts of problems I outlined above: i.e., the fact that in QM we only have half the set of boundary variables that we have in classical mechanics (i.e., in QM you cannot specify both initial position and momentum as you can in classical mechanics, and then turn around and give up momentum in exchange for specifying final position).

      I have been working on this stuff for almost fifty years (not continuously of course!), I have actually created an alternative to Bohmian mechanics (with similar shortcomings), and I have some reasonable (though not encyclopedic) knowledge of others' work, ranging from Edward Nelson to Asher Peres to Mikio Namiki.

      I'm just reporting to you what seems to me to be the source of the problem that has stymied everyone.

      My explanation is not intended to be a mathematical proof.

      It's just my description of the obstacles I have seen everyone dealing with along with the well-known facts about QM vs. classical mechanics that seem to be the source of those obstacles.

      I will say that my working style is that of old-fashioned physicists, not twentieth-century mathematicians: i.e., I want to try to deal with a concrete model or concrete equation instead of laying out abstract axioms that I hope will be fruitful. (Of course, that is a parody of how real mathematicians work: it is merely the Bourbakist / Emmy Noether influence on how they finally write it up, not how they really discover things.)

      Maybe there is some way to work around this obstacle. For example, if we used the real part of the initial wave function and the imaginary part of the final wave function, this would get around my objection about counting boundary data (I am almost sure that will not work for other reasons, alas).

      Or maybe we should just use the initial and final QM probability and dump the phases (I am doubtful this will work but not certain).

      Or perhaps I completely misconceive what the obstacle is, or a really abstract way of attacking the problem is needed that is alien to me, or whatever.

      I do think, however, that I am giving an accurate description of what has gone wrong so far.

      Of course, if I actually knew the right way to solve the problem, I’d be writing it up rather than chatting with you about why none of us has succeeded!

      All the best,

      Dave

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    13. From one side you would like to go to symmetric models, from the other you start with Schrödinger equation - which contains bias of broken symmetry.

      It is analogous to starting with Euler-Lagrange, enforcing some direction of evolution.
      But if physics is fundamentally symmetric, shouldn't it solve its equations in a symmetric way, like through the least action principle instead?
      Then we can go to mathematically equivalent Euler-Lagrange, but with hidden state originally chosen in symmetric way - also accordingly to all future measurements, as in superdeterminism.

      Returning to QM, focusing on Schrödinger you enforce asymmetry as in Euler-Lagrange.
      If physics is symmetric, we need to start with symmetric formulation instead - like path ensembles.
      Then transforming to Schrödinger evolution, its hidden state was already chosen in time symmetric way, also accordingly to all future measurements - as in superdeterminism.

      I also don't like abstract examples, so let us be more concrete: what stationary probability distribution should we get in [0,1] range?
      Any diffusion/chaos gives uniform rho=1.
      QM and uniform path ensemble (maximal entropy random walk) gives rho~sin^2.
      How do you explain such rho~sin^2 localization?

      All the best,
      Jarek

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    14. Kakaz wrote:
      >Second: gravitational systems tend to collapse, and finally it may seem to single black hole, but there are stable periodic configurations ( we solar system, see KAM theorem) so basically we cannot easily say state with black hole is final state of such systems.

      Those "stable" configurations radiate gravitational radiation, so they are not literally stable forever (yes, I know: it takes a long, long time!).

      Kakaz also wrote:
      >From above it may follow that statement that at Big bang universe was at low entropy is false.

      Well.... the entropy of the universe has been increasing you know, for like 13 billion years or so! Burning of hydrogen in stars and all that.

      Kakaz also wrote:
      > Third: black hole entropy is maximal one, and you cannot make it bigger.

      If you are implying that the universe at the Big Bang was a black hole, you are mistaken.

      I grant you that gravity makes it harder to apply thermodynamics, but I do not think your conclusion follows from what you have stated.

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    15. ps. Nice animation by Öjvind Bernander about such 4D spacetime symmetric view on locality, avoiding our human symmetry-breaking biases leading e.g. to Bell-like problems:

      https://www.youtube.com/watch?v=P-TgKIunUf0

      Regarding symmetric views on QM, more abstract version of Maximal Entropy Random Walk view is Zambrini's Euclidean quantum mechanics - using Bernstein process:
      https://journals.aps.org/pra/abstract/10.1103/PhysRevA.35.3631

      Delete
    16. Jarek Duda wrote to me:
      >From one side you would like to go to symmetric models, from the other you start with Schrödinger equation - which contains bias of broken symmetry.
      >It is analogous to starting with Euler-Lagrange, enforcing some direction of evolution.
      >But if physics is fundamentally symmetric, shouldn't it solve its equations in a symmetric way, like through the least action principle instead?

      Well, the path integral just is the Schrödinger equation or, more precisely, a way of solving the Schrödinger equation.

      So, any time asymmetry you see in the Schrödinger equation is also there in the path-integral approach.

      By the way, the Schrödinger equation does not really have a time asymmetry: it has in fact a perfectly nice time symmetry (of course you have to complex-conjugate the wave function).

      Time symmetry or asymmetry is not the issue. The problem is that, with the Schrödinger equation (or, quite equivalently, with the path-integral approach), you cannot specify both the initial and the final state. The equation just does not give you that many degrees of freedom.

      That is the central point I am trying to hammer away at: the Schrödinger equation is not time asymmetric -- that is not the problem. The problem is that you just do not have enough degrees of freedom in QM to specify initial and final states, as you can do in classical mechanics.

      The path integral works the same way because it is just a method for solving the Schrödinger equation. I dislike the path integral not for any physics reason but simply because I notice that, for some reason, people who work with the path integral, when considering quantum foundations, instead of the Schrödinger equation find it easier to spin away into outer space, into superficially appealing nonsense.

      By the way, I took QM from Richard Feynman in the 1974-'75 academic year at Caltech. Feynman emphasized the Schrödinger equation, not the path integral, although obviously Feynman had no personal aversion to the path integral! It is just that the Schrödinger equation tends to be the clearer guide to help one understand QM.

      Jarek also wrote:
      >Then we can go to mathematically equivalent Euler-Lagrange, but with hidden state originally chosen in symmetric way - also accordingly to all future measurements, as in superdeterminism.

      Well, as I keep saying, to the best of my knowledge, no one has ever managed to make that work. I think you and I agree that no one has ever made it work taking as the starting point the Schrödinger equation, and I think I have explained here why.

      And, I think I have also explained why if the Schrödinger equation will not work, then neither will the path integral, since they are basically the same thing in non-relativistic QM (i.e., I am ignoring QFT issues such as gauge fixing, ghosts, etc.)

      Except it has proven easier for people to fool themselves with the path integral into thinking they can succeed, though they have not.

      I have suggested above two ways around my argument, neither of which will probably work, but this does demonstrate that if we are aware of why the approach that works in classical physics fails in QM (losing half the state variables) then being aware of this fact may help us someday succeed.

      Every single one of us working in quantum foundations is missing something. I do not know what the missing insight is. But at least understanding why all attempts to date have failed may help clear up a little bit our view of the problems we face.

      All the best,

      Dave

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    17. Indeed there is transformation between Schrödinger equation and Feynman path ensembles, analogously as between Euler-Lagrange and the least action principle - in this sense we can say that they are mathematically equivalent.

      However, as I am trying to emphasize here, there is a big difference between solutions chosen using each of them:
      - in Schrödinger or Euler-Lagrange you assume that initially there was only initial point in the past, and solution evolves from there - they contain asymmetry bias.
      - this bias is removed in symmetric formulations: path ensembles, least action principle, which conclude solution from initially fixing in both time directions. Then transforming to a biased formulation, its state was originally chosen also accordingly to future measurements - as in superdeterminism.

      While I see you just neglect such possibility, mathematically it is not a problem to choose solution in unbiased (symmetric) way, like in maximal entropy random walk Wikipedia derivation you have ignored:
      Consider ensemble of paths from t-l to t+l, looking only at situation near t.
      Then perform l-> infinity limit, directly getting Born rule, e.g. rho~sin^2 stationary probability distribution in [0,1].

      All the best,
      Jarek

      Delete
    18. Jarek Duda wrote to me:
      >However, as I am trying to emphasize here, there is a big difference between solutions chosen using each of them...

      And I am trying to tell you that you are wrong! And I have explained why I think you are wrong.

      We are going around in circles because you seem unwilling to believe that I truly, honestly am strongly convinced that you are wrong, and that I know a lot about this stuff and have for many decades.

      Jarek also wrote:
      >While I see you just neglect such possibility, mathematically it is not a problem to choose solution in unbiased (symmetric) way...

      No, I do not "neglect" this, I am convinced it is impossible and have given reasons why.

      Jarek also wrote:
      >Then perform l-> infinity limit, directly getting Born rule, e.g. rho~sin^2 stationary probability distribution in [0,1].

      I do not believe this has ever been done: I know you can point to someplace where someone gins up the function rho~sin^2. But I do not believe anyone has ever used this sort of technique to, in general, derive the Born rule. I am beginning to wonder if you know what the phrase the "Born rule" actually refers to.

      How on earth would you get the Born rule???

      Look: I have known for decades about "Wick rotations" and how you get the ground state by going to imaginary time and taking the t goes to infinity limit and how you can get VEVs and all the rest. This is very old hat.

      I know how random walks work and Brownian motion and the diffusion equation work and I know the mathematical analogy between the diffusion equation and the Schrödinger equation. Again, all very old hat.

      But none of this solves the problem of giving a realist model that gives Bell entanglement. And none of it gives you the Born rule.

      I took Quantum Mechanics from the Nobel laureate Richard Feynman in the 1974-'75 academic year. I took Quantum Field Theory from the Nobel laureate Steve Weinberg in the late 1970s when he was on sabbatical at Stanford.

      I have known about all this stuff for a long time.

      I know you can point me to many references that contain all this material I already know.

      I am trying to tell you that none of that stuff does in fact derive the Born rule or create a realist model (in Minkowski space, not 4-D Euclidean space, which is irrelevant).

      Now, unlike the matters I have debated with antooneo, Yablon et al., which were really open and shut, you and I both know that what you and I are debating is very complex. It is possible that there are some holes in my argument that I have missed.

      If you can show me someone who has really, actually derived Born's rule and created a well-defined realist model in Minkowski space that exhibits Bell entanglement, then you can show my argument is wrong.

      I do not think you can. You certainly have not done so yet.

      I honestly hope you can come up with something -- it would be extremely cool to have a solution to the quantum measurement etc. problems.

      But you haven't yet. And I am pretty sure you can't.

      Please try to understand that merely pointing to stuff that everyone in the field is aware of, particularly the imaginary-time/Euclidean-space techniques that simply do not derive the Born rule, much less create a realist model of QM in Minkowski space (!), is just a waste of time.

      I have known about that stuff for a longer time than many commenters here have been alive. And that stuff does not work to derive the Born rule or create a realist model of QM (in Minkowski space).

      Dave

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    19. Dave,
      You use lots of authority arguments, but I still haven't seen a single concrete one for your impossibility claims.
      I understand you have decades of experience, but as you say it didn't lead you to understanding - maybe it is worth to at least try to relax for a moment your asymmetric way of thinking.

      Please let us focus on the simplest situation: [0,1] range.
      Standard diffusion, chaos etc. gives uniform stationary probability distribution, QM gives localized rho~sin^2.

      This rho~sin^2 is one of the most basic problems on the way to understand QM - do you have any explanation?

      Assuming the simplest time symmetric statistical physics model: uniform probability distribution among paths, we get exactly this rho~sin^2:
      https://en.wikipedia.org/wiki/Maximal_Entropy_Random_Walk

      It is also random walk finally chosen accordingly to the Jaynes maximal entropy principle (standard RW usually only approximates it leading to uniform rho=1).
      Is it only a coincidence that the simplest time symmetric model just works?

      All the best,
      Jarek

      Delete
    20. Jarek Duda wrote to me:
      >You use lots of authority arguments...

      Hey, I'm an authority? Well, thanks, Jarek.

      Jarek also said:
      >Please let us focus on the simplest situation: [0,1] range.
      >Standard diffusion, chaos etc. gives uniform stationary probability distribution, QM gives localized rho~sin^2.

      >This rho~sin^2 is one of the most basic problems on the way to understand QM - do you have any explanation?

      You are talking about a very simple function that occurs in lots of places. I see no reason why you find this of interest. Coincidences happen.

      Honestly, your example seem to me to have no more content than Jay Yablon's silly neutrino nonsense, also resting on a coincidence (he had two different calculations that both gave answers of around 15 minutes), and which even he admitted was wrong when I pointed it out.

      All you seem to have is a system that gives the same function as the ground state wave function for one very simple QM problem, a particle in a box. Just the ground state, not excited states, not time dependent states, not other potentials, not composite systems, not much of anything, really. This seems to be due to the fact that the Laplacian shows up in both places: the Laplacian shows up damned near everywhere, which is why we insist students learn about it.

      Coincidences happen: simple functions show up all over the place in math and physics. If all you have is that this one function happens to show up in one place in QM and also in one place in some other application, well, you have not been involved very long in STEM if you have not seen this sort of coincidence happen again and again and again and again.

      My claim is that no one has in fact taken the approaches you suggest and produced an actual, realist model of quantum mechanics for obvious systems: the general time-dependent state of the simple harmonic oscillator, to take one obvious example.

      Much less has anyone taken the approach you suggest and produced a realist model that reproduces the violation of Bell's inequality.

      I have suggested why that is, but, yes, I might be wrong.

      Show me a single counter-example to my claims and prove me wrong. That might actually be possible, but I do not think so.

      Jarek also wrote:
      >Assuming the simplest time symmetric statistical physics model: uniform probability distribution among paths, we get exactly this rho~sin^2:
      https://en.wikipedia.org/wiki/Maximal_Entropy_Random_Walk

      >It is also random walk finally chosen accordingly to the Jaynes maximal entropy principle (standard RW usually only approximates it leading to uniform rho=1).

      >Is it only a coincidence that the simplest time symmetric model just works?

      Since you apparently cannot extend it to, say, the time-dependent state of the simple harmonic oscillator, yes, it does actually appear to just be a coincidence. One example is a coincidence. Extend it to the time dependent states for the simple harmonic oscillator, for the quantum Coulomb potential, etc. and you will force me to admit it is more than a coincidence.

      ""One swallow does not a summer make..." nor one example anything more than a coincidence.

      In any case, all you seem interested in is reproducing a quantum probability distribution for the ground state of an isolated system: as I keep hammering away at, QM is more than that -- in particular, QM is a violation of the Bell inequality.

      As far as I can tell, our disagreement is simply that you are really, really, like super-impressed by one simple example that could easily be a coincidence, and I am just not impressed in the slightest.

      Am I missing something?

      Dave

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    21. Sure Maximal Entropy Random Walk extends to any potential, in continuous limit its discrete Schrödinger equation becomes standard continuous one.
      And it is not a surprise, as mathematically it is nearly Feynman path integrals after Wick rotation.

      But it has different motivation - it is just diffusion done right: not knowing path of an object, the safest assumption is the maximizing entropy one, or equivalently assuming uniform/Boltzmann distribution among paths.
      This way we e.g. get the localization property missing in standard diffusion - e.g. preventing conductance in semiconductor.

      But I see MERW only as a toymodel, starting with understanding this rho~sin^2 in [0,1].
      Standard diffusion gives rho=1.
      Ensemble of one-directional paths: toward past or future, would give rho~sin (or generally rho~psi).
      Finally symmetric: ensemble of complete paths gives rho~sin^2 as we need to multiply both - we get intuition of Born rule being direct consequence of time symmetry.
      Having Born rule, we can construct Bell violation examples - page 9 in https://arxiv.org/pdf/0910.2724

      You haven't replied - so how do you understand this rho~sin^2 localization in [0,1]?

      All the best,
      Jarek

      Delete
    22. Jarek Duda wrote to me:
      >Having Born rule, we can construct Bell violation examples - page 9 in https://arxiv.org/pdf/0910.2724

      This is the first time I have seen you reference your paper -- now I can actually look at the details of what you are doing!

      It will take me a few days to work through it, then I'll give you my comments.

      I should warn you that, in all probability, my comments will be negative, for the simple reason that almost all work in quantum foundations (aside from the applied stuff on quantum encryption, etc.) has turned out to be wrong. But perhaps your paper willl be a pleasant exception.

      Jarek also asked:
      >You haven't replied - so how do you understand this rho~sin^2 localization in [0,1]?

      Well, as I said, I think it is coincidence, due to both involving the Laplacian.

      As you say,
      >But it has different motivation - it is just diffusion done right: not knowing path of an object, the safest assumption is the maximizing entropy one, or equivalently assuming uniform/Boltzmann distribution among paths.

      But now that I know to look at your paper, we'll see. Maybe your paper will show me it is not a coincidence.

      All the best,

      Dave

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    23. Maximal Entropy Random Walk is very useful general tool - euclidean path ensembles made into discrete or continuous random walk, e.g. our 2009 PRL paper has now ~140 citations, generally its Wikipedia article has nice introduction.

      Ising model can be seen as spatial example of its application (details: https://arxiv.org/pdf/1912.13300 ): let M_uv = exp(-beta E_uv) be its transition matrix using energies of neighboring spins/values. Find its dominant eivenvalue/vector: M psi = lambda psi.

      Now probability of u in such Boltzmann distribution of infinite sequences of spins (or something more general) is
      Pr(u) = (psi_u)^2
      of neighboring (u,v) pairs is:
      Pr(uv) = psi_u (M_uv / lambda) psi_v
      The former resembles Born rule due to using sequences infinite in both directions, the latter resembles TSVF - if only imagining that this Ising sequence is in time direction.

      Discrete Laplacian x_{t+1} - 2x_t + x_{t-1} comes here from discretization of adjacency matrix for 1D lattice, becomes continuous one in infinitesimal limit.
      MERW uses dominant eigenequation: maximizing |lambda| - which has interpretation as minus energy, hence it corresponds to finding the ground state.

      All the best,
      Jarek

      Delete
  6. String gas "Sosmology"? I guess it is Cosmology, xD. Typos!
    Happy 2019 ending and new Year 2020!

    ReplyDelete
  7. I read many years ago that a physicist theorized that universes were created when a black hole exceeded the point of maximum mass, basically ripping into, and depositing it's entire contents into a new space/time. I wonder what became of that theory? If a black hole suddenly disappeared from our observable universe would that prove the theory?

    ReplyDelete
    Replies
    1. I have no idea what that even mans. What's a "point of maximum mass" for a black hole? Black holes can have any mass.

      Delete
  8. Sabine Hossenfelder wrote:
    “...and then there is the so-called Unicorn Cosmology, according to which our universe grew out of unicorn shit. Nah, I made this one up.”
    ----------------
    Sabine, doesn’t making something up imply free will? In which case, wouldn’t that be antithetical to your belief in superdeterminism?

    Not meaning to sound like a broken record here,...

    ...but the bottom line is that no matter how the universe began, the fact that it was “impregnated” with every possible ingredient necessary to awaken us into existence, seems to be just as mysterious.

    Indeed, in considering the initial state of the universe in contrast to where it is today...

    ...it’s almost as if it began as a “seed-like” phenomenon that, after sprouting and reaching a certain stage of its physiological maturity, is now able to yield-forth the “fruit” of life and consciousness.

    In other words, it’s as if the universe began with a teleologically-driven end-goal that was somehow inscribed in its informational underpinning.

    Either that or some unfathomable level of intelligence has been guiding it. And I say that because the alternative (i.e., “chance”) is pure and utter nonsense.

    Ah, but I guess I’m venturing into the realm of philosophy and theology now, eh?

    But hey, this just puts superdeterminism (or at least, determinism) in a more “natural” sounding context, so don’t knock it.

    In my defense, I am simply playing with the implications of what science itself is discovering about reality.

    ReplyDelete
    Replies
    1. No, "making something up" does not require free will. I have no idea why you think so. Bots "make up" shit all the time.

      Delete
    2. Keith wrote to Sabine:
      >In other words, it’s as if the universe began with a teleologically-driven end-goal that was somehow inscribed in its informational underpinning.

      Keith, to quote Laplace, we have no need for that hypothesis.

      We have done amazingly well at explaining everything from the early universe (see Weinberg's classic book) to the life cycle of stars to plate tectonics to the functioning of living organisms to the details of molecular and atomic structure using non-teleological theories.

      No, we do not understand everything, and we probably never will for the simple reason that some historical evidence has been blotted out by later events: whatever preceded the Big Bang was lost in the catastrophic explosion and the first cell was surely eaten by a later life form!

      But we see no need for teleology.

      Keeith also wrote:
      >Ah, but I guess I’m venturing into the realm of philosophy and theology now, eh?

      Perhaps honest theology and philosophy should be guided by the evidence, eh?

      And, yes, I am well aware that no one understands consciousness: but our lack of understanding is not evidence of teleology. Sometimes, human ignorance is just ignorance, not evidence for anything at all.

      Delete
    3. PhysicistDave wrote:
      Keith wrote to Sabine:
      ">In other words, it’s as if the universe began with a teleologically-driven end-goal that was somehow inscribed in its informational underpinning.

      Keith, to quote Laplace, we have no need for that hypothesis.

      We have done amazingly well at explaining everything from the early universe (see Weinberg's classic book) to the life cycle of stars to plate tectonics to the functioning of living organisms to the details of molecular and atomic structure using non-teleological theories."
      ----------------
      Dave, considering the fact that a literal eternity preceded the emergence of our little universe a mere 13.8 billion years ago, then I wouldn’t be too impressed with the explanations offered-up by what may turn out to be the metaphorical equivalent of amoebas splashing around in a petri dish.

      Now I realize that I am entering into highly speculative territory here, but what I mean is that considering how far our minds have evolved in the context of a few million years, then just imagine how far mind could evolve if it literally had forever (as in an eternal past) to do so.

      You just need to be open to the possibility that not only is ours not the first universe, but also that mind and consciousness itself may not require being encased in physical matter in order to exist.

      PhysicistDave wrote:
      “No, we do not understand everything, and we probably never will for the simple reason that some historical evidence has been blotted out by later events: whatever preceded the Big Bang was lost in the catastrophic explosion and the first cell was surely eaten by a later life form!

      But we see no need for teleology.”
      ----------------
      My stock answer to the hardcore form of materialism you seem to be espousing is that it never ceases to amaze me how incredibly ironic it is that our exponentially growing accumulation of knowledge can reveal mind-blowing levels of complexity and order in how the universe is constructed,...

      ...yet the more complex and ordered it seems to be, the more willing some humans are to think that the order is founded upon “serendipity.”

      Dave, be honest and tell me that if you were a gambling man, then which of the following two choices would you bet the farm on as being the most plausible explanation for the unthinkable order of the universe: “intelligence” or “blind luck”?

      PhysicistDave wrote:
      "Perhaps honest theology and philosophy should be guided by the evidence, eh?"
      ----------------

      I couldn’t agree more, Dave.

      And the evidence being established by physics itself is pointing toward “idealism,” in that quantum mechanics seems to be suggesting that all of reality is created from a mind-like substance.

      And I say it is “mind-like” because it appears to be capable of being formed into absolutely anything “imaginable.”

      Now there are other things that point to idealism, however, this post is already too long.

      Delete
    4. Sabine Hossenfelder wrote:
      “...and then there is the so-called Unicorn Cosmology, according to which our universe grew out of unicorn shit. Nah, I made this one up.”
      ----------------
      Sabine, upon deeper reflection, I believe that a smelly cousin to your “Unicorn Cosmology” may reside in Everett’s Many Worlds cosmology.

      Now I know I mentioned this in one of your other threads, but if we were to take Everett’s theory seriously...

      (of which many prominent physicists actually do)

      ...then we need to face the real possibility that our own universe may not have originated 13.8 billion years ago in a Big Bang.

      No, because if the Many Worlds theory is true, then we may owe our existence to a “branching” that might have occurred...

      (perhaps only a few minutes ago)

      ...due to the quantum events that took place in the methane from a bear farting in the woods in an alternate universe.

      In which case (as was mentioned in that other thread), we are not here as the result of a “Big Bang,” but from a recently expelled “tiny toot” of fart gas (and yes, as ridiculous as that sounds, I’m being serious).

      The point is that if you are going to ask:

      “How did the Universe begin?”

      ...then other than the sketchiness regarding the existence of unicorns compared to bears, then the stinky source from which the universe arose according to your “Unicorn Cosmology” isn’t that far off from what can be inferred from Everett’s cosmology.

      Now setting the “tiny toot theory” aside, I find it curious that the “Many Worlder” physicists that I know of...

      (such as Sean Carroll and Max Tegmark, for example)

      ...always appear to assume that our particular universe is the initial source of all of the branchings, and never seem to realize or acknowledge that it may only be a “seconds old” branch of a branch of a branch,...

      ...with us humans merely being the copies of some infinitely far removed originals.

      To me, that’s just another shining example of how tiny their efforts have been in considering the actual implications of the theory.

      Delete
    5. Keith Gill wrote to me:
      >Dave, considering the fact that a literal eternity preceded the emergence of our little universe a mere 13.8 billion years ago, then I wouldn’t be too impressed with the explanations offered-up by what may turn out to be the metaphorical equivalent of amoebas splashing around in a petri dish.

      That applies to "metaphysicians" such as yourself as well as to physicists -- except that the physicists have evidence!

      I think I'll rely on the ameobas that have evidence.

      Keith also wrote:
      >Now I realize that I am entering into highly speculative territory here, but what I mean is that considering how far our minds have evolved in the context of a few million years, then just imagine how far mind could evolve if it literally had forever (as in an eternal past) to do so.

      Alas, all the minds we know of die. Planets eventually become uninhabitable. If you assume "eternal inflation," as you seem to be doing, stars eventually die out in those other universes -- and, most importantly, there is no knows way to communicate from them to us anyway.

      Keith asked me:
      >Dave, be honest and tell me that if you were a gambling man, then which of the following two choices would you bet the farm on as being the most plausible explanation for the unthinkable order of the universe: “intelligence” or “blind luck”?

      That is very easy to answer: "blind luck."

      For thousands of years, people have offered supposed evidence for the other answer (some higher "Intelligence"(; yet, none of that evidence has panned out and that supposed omnipresent Intelligence has kept Himself well hidden.

      On the other hand, the "blind luck" hypothesis keeps winning and winning in terms of evidence.

      I'm quite honest in admitting that I do not know with any degree of certainty either the nature of consciousness or the ultimate role of consciousness in the universe.

      But, as you suggest, if I were forced to choose between the choices as you frame them, I honestly would go with "blind luck." I suspect most scientists would.

      Keith also wrote:
      >My stock answer to the hardcore form of materialism you seem to be espousing...

      Wouldn't an espouser of "hardcore materialism" be claiming that physics can explain consciousness? I've said nothing of the sort: I doubt that physics as it now exists can explain consciousness.

      I am skeptical towards both hard-core materialism and your own alternatives. I am a skeptic in general unless there is evidence: that is my job as a scientist.

      Keith also wrote:
      >And the evidence being established by physics itself is pointing toward “idealism,” in that quantum mechanics seems to be suggesting that all of reality is created from a mind-like substance.

      Well, your claim about QM seems not to be obvious to most physicists! Maybe QM has something to do with consciousness, maybe not. Evidence, you know.

      You seem to think that people who are skeptical of your claims must dogmatically adhere to what you conceive as the opposite view.

      In fact, some of us are willing to wait for evidence.

      Dave

      Delete
    6. I wrote to PhysicistDave:
      "Dave, considering the fact that a literal eternity preceded the emergence of our little universe a mere 13.8 billion years ago, then I wouldn’t be too impressed with the explanations offered-up by what may turn out to be the metaphorical equivalent of amoebas splashing around in a petri dish.”

      To which PhysicistDave responded with:
      “That applies to "metaphysicians" such as yourself as well as to physicists -- except that the physicists have evidence!

      I think I'll rely on the ameobas that have evidence.”
      ----------------
      You are absolutely correct to point out how it also applies to metaphysicians such as me. And yes, evidence is always better than pure speculation.

      However,...

      (and I apologize in advance for constantly harping about the Many World’s theory)

      ...when the “amoebas” (physicists) that you rely on, take what they believe is evidence...

      (elegant mathematical formulas, for example)

      ...and use it to support ideas such as trillions of copies of the universe instantly branching off of this universe because of what occurs with respect to particles of light as we gaze at our computer screens for a few seconds,...

      ...then it becomes obvious that the “evidence” is generating ideas in the minds of physicists that are every bit as dubious (ludicrous) as anything that a metaphysician (or theologian) could fabricate.

      So perhaps it is the “interpretation” of the evidence that is at issue here?

      For example, I don’t know what the physicist in you sees when the “evidence” shows that 99.9999999 percent of physical matter is actually empty space,...

      ...but what I see is that what we consider to be “solid” and “real” in the universe is nothing more than an “illusion” involving fields of information and the forces of electromagnetism, working in tandem with the five senses of our consciousness.

      In other words, the objective phenomena of the universe bear a striking resemblance to the subjective phenomena we encounter during a vivid dream, which can also seem quite solid and real (hence, another reference to idealism).

      Furthermore, when the “evidence” garnered by quantum physicists leads to the (yet to be resolved) issue of whether or not consciousness might somehow be involved in the collapse of the wave function....

      (without which, the phenomenal structures of what we call “reality” will not even take form)

      ...it is yet another indication of idealism.

      Like I said, I don’t know what the physicist in you sees when encountering the “evidence” mentioned above, but I think it’s safe to assume that it’s not quite the same as what I am seeing.

      Keith

      Delete
    7. Keith D. Gill wrote to me:
      >However,...

      >(and I apologize in advance for constantly harping about the Many World’s theory)

      >...when the “amoebas” (physicists) that you rely on, take what they believe is evidence...

      Keith, if you have been following these comment threads on Sabine's blog, you know that I am a very harsh critic of Many Worlds: there are very, very serious and well-known technical problems with MWI, the best known of which are the so-called "preferred-basis problem" and the "probability-measure problem." I have also pointed out that the whole idea of "branching universes" is just plain wrong: the mathematical principle of unitarity requires that the number of possible "branches" be conserved in time. And, I think Sabine has made the point that how MWI connects with the textbook presentation of QM -- Hermitian operators corresponding to observables whose eigenvalues are the possible result of measurements, etc. -- is, to put it kindly, unclear. And then there is the little matter of MWI blatantly violating Occam's razor by creating entities that can never be observed!

      So, if you want to claim that your speculations are no worse than MWI, you are, from my perspective, setting a very, very low bar indeed!

      MWI is known to be wrong. But it does lead to some entertaining sci-fi.

      Keith also wrote:
      >For example, I don’t know what the physicist in you sees when the “evidence” shows that 99.9999999 percent of physical matter is actually empty space,...

      I see the real world.

      You know the story about Wittgenstein?

      >"Meeting a friend in the corridor, Ludwig Wittgenstein (1889-1951) said: 'Tell me, why do people always say that it was natural for men to assume that the sun went around the earth rather than the earth was rotating?'

      >"His friend said: 'Well, obviously, because it just looks as if the sun is going around the earth.'

      >"To which the philosopher replied: 'Well, what would it look like if it had looked as if the earth were rotating?'"

      The world looks the way I would expect it to look if the modern theory of atoms, radiation, and so on were in fact true.

      How else should it look? The empty space between the electrons and the nucleus is far, far smaller than the wavelength of visible light, so of course we cannot see those spaces with our eyes that are only sensitive to visible light.

      We can indeed "see" it with much shorter wavelength radiation, but our eyes are not sensitive to such radiation.

      The world looks the way it would look if modern science is correct: no accident, of course, since modern science is based on observations of the real world.

      I fear that fellows like you have not thought this through at all. Modern science is an essentially correct description of the way things are: your body (I leave aside your consciousness -- no one understands consciousness) really is just a big collection of little bags of biochemicals swirling and reacting. The earth really is spinning at about 1000 mph at the equator. A hundred million years ago or so, your ancestors were rather unimpressive little mammals, and you yourself (and all the rest of us, of course) are still just primates among primates whose primate nature is often all too obvious. The whole observable universe really exploded around 14 billion years ago, give or take, from a very small volume. Cosmic rays really are ripping through your body every second and, alas, occasionally damaging your DNA in ways that could produce cancer. (Fortunately, almost all of the trillions of neutrinos that pass through your body each second have no effect at all.)

      That's what I see when I look at the world because that explains our most careful observations of reality, of the real world.

      Delete
    8. PhysicistDave wrote:
      “Keith, if you have been following these comment threads on Sabine's blog, you know that I am a very harsh critic of Many Worlds: there are very, very serious and well-known technical problems with MWI,...

      ...So, if you want to claim that your speculations are no worse than MWI, you are, from my perspective, setting a very, very low bar indeed!”
      ----------------
      You are a good man, Dave, and I truly appreciate your extremely intelligent and measured responses to my metaphysical blatherings.

      However, with that being said, you are missing my point.

      You insisted on the importance of “evidence.”

      The problem is, that for a small percentage of the more vocal and popular physicists (such a Sean Carroll and Max Tegmark) the evidence is causing them (especially Carroll) to promote the Many Worlds tripe.

      Now if you tell me that from the perspective of the more reasonable physicists (such as yourself) that Carroll and Tegmark are just a couple of clueless hacks who are only seeking attention, then that’s a different story. But it still doesn’t change the fact that bonafide physicists are using the “evidence” to promote nonsense.

      PhysicistDave wrote:
      “I see the real world.”
      ----------------
      According to certain interpretations of quantum mechanics, what you are referring to as being “real” is summed-up nicely in a quote from physicist Nick Herbert’s book - QUANTUM REALITY: BEYOND THE NEW PHYSICS:

      “Though ghostly and transitory, Heisenberg’s shimmering ocean of potentia is the sole support for everything we see around us. The entire visible universe, what Bishop Berkeley called “the mighty frame of the world,” rests ultimately on a strange kind of being no more substantial than a promise.”

      Now I am not suggesting that there isn’t something “real” out there - something that underpins and steadfastly (deterministically) presents the phenomenal structures of the universe to us in the common forms of what we all can see, feel, hear, taste, and smell.

      However, the unresolved “measurement problem” still holds the possibility that if there was no life and consciousness present in the universe to look at, touch, listen to, taste, or smell those forms,...

      ...then the forms may ultimately exist as nebulous fields of energy and information.

      And the point is that if our minds were not constantly experiencing our surroundings through the multi-sensory interface of our bodies, then what you are referring to as being the “real world” might not be quite as real as you think.

      In other words, as Herbert suggested, its ultimate status may be something that is “...no more substantial than a promise.”

      At the very least, Dave, we need a deeper explanation as to what the word “real” actually means and applies to.

      PhysicistDave wrote:
      “I fear that fellows like you have not thought this through at all. Modern science is an essentially correct description of the way things are...”
      ----------------
      Well, I think I have thought it through enough to realize that all humans (including myself) are basically sleepwalking through life.

      And that the more heartfelt and passionate some humans are in articulating their faith in materialism,...

      (more specifically, their faith in the “chance” hypothesis)

      ...then the more they demonstrate -- in direct proportion to the intensity of their faith -- the depth and degree of their somnambulism.

      Again, Dave, I greatly appreciate your honest and intelligent replies, and I hope that you will always receive what I say in return as coming to you in the spirit of fun and friendly debate. :)

      Delete
    9. Sabine Hossenfelder wrote:
      No, "making something up" does not require free will. I have no idea why you think so. Bots "make up" shit all the time.
      ----------------
      No, bots present the results (a readout) of algorithmic processes that are purely mechanical in nature.

      In other words, when someone speaks a command to the bot “Alexa” and it responds by performing a task,...

      (such as turning the lights on or off)

      ...what is happening is just a modern-day version of loading one of those perforated rolls into an old-time player piano, and a specific song is performed.

      Except, instead of Alexa mechanically reading and responding to the coding on a roll of paper, it mechanically reads and responds to specific waveforms of sound via a speech recognition program.

      Again, what is taking place is purely mechanical in nature.

      Whereas, on the other hand, the human brain (unlike a bot) possesses an epiphenomenal presence (an emergent consciousness) that seems to exist above and outside of the physical properties of the unconscious brain materials.

      And it is that epiphenomenal consciousness...

      (the proverbial “ghost in the machine,” if you will)

      ...who not only possesses the “free will” to ignore the command, but can also experience the emotionally-charged sensation of “indignation” as it tells you to turn the lights on yourself, you lazy bum.

      Sabine, do you think that a bot could ever experience the “feeling” (the qualia) of indignation at being commanded to perform a menial task?

      Or how about the self-satisfying sense of “pleasure” of crafting and performing an original piece of music?

      If yes, then please explain how?

      And if no, then you have no business using bots (unconscious “machines”) in a comparison with humans in order to support your argument against free will.

      I guess the bottom line is that in the same way that you have no idea why I think that “making things up” implies free will; likewise, I have no idea why you cannot see a distinct difference between mind and matter.

      Keith

      Delete
    10. Keith D. Gill wrote to me:

      >The problem is, that for a small percentage of the more vocal and popular physicists (such a Sean Carroll and Max Tegmark) the evidence is causing them (especially Carroll) to promote the Many Worlds tripe.

      >Now if you tell me that from the perspective of the more reasonable physicists (such as yourself) that Carroll and Tegmark are just a couple of clueless hacks who are only seeking attention, then that’s a different story. But it still doesn’t change the fact that bonafide physicists are using the “evidence” to promote nonsense.

      Keith, I think part of the problem here is that you think I am defending physicists.

      I'm not.

      I am defending those areas of physical science -- special relativity, quantum mechanics, the Big Bang, the Standard Model of particles physics, etc. -- that have been fairly well-established by the scientific method.

      Some established physicists are scoundrels or idiots. That is unfortunate, but I do not much care. I do care about the scientific method and what we actually know about the physical world.

      Note: I did not include cosmic inflation or string theory among those well-established physical theories. In fact, neither cosmic inflation nor string theory is actually one single theory: they are frameworks for theories with which physicists are playing around, hoping to come up with a definite theory which can be definitively tested.

      Someday they may succeed. Not yet.

      As to Sean Carroll and Max Tegmark and MWI, there is a historical reason why cosmologists have been attracted to MWI. We were all taught textbook QM in which the world is divided into a quantum system and a classical observer. But, in trying to apply QM to cosmology, to the entire universe, there is no place to put the classical observer outside the universe. So, cosmologists looked to some approach to QM different from the textbook approach.

      Bohmian mechanics words weirdly with relativity and so most rejected that. The other well-known approach was MWI, and so many cosmologists latched on to that.

      And most cosmologists are not experts on quantum foundations, so they are not fully aware of the (to my mind conclusive) objections to MWI.

      Keith also wrote:
      >the forms may ultimately exist as nebulous fields of energy and information.

      Keith, you like poetry, but using the poetic term "nebulous" changes nothing. Similarly, with the poetry you quote from Nick Herbert.

      Keith also wrote:
      >And that the more heartfelt and passionate some humans are in articulating their faith in materialism,...

      >(more specifically, their faith in the “chance” hypothesis)

      >...then the more they demonstrate -- in direct proportion to the intensity of their faith -- the depth and degree of their somnambulism.

      More poetry, I fear.

      And, you really should stop attributing to all of us scientists some weird "faith in materialism" simply because we lack your faith in teleology.

      As I keep trying to tell you, Keith, there are more ways of viewing the world than are dreamt of in your philosophy!

      Dave

      Delete
    11. PhysicistDave wrote:
      “Keith, I think part of the problem here is that you think I am defending physicists.

      I'm not.

      I am defending those areas of physical science -- special relativity, quantum mechanics, the Big Bang, the Standard Model of particles physics, etc. -- that have been fairly well-established by the scientific method.”
      ----------------
      No, Dave, I don’t think that you are defending physicists, per se; I think (as per your own earlier assertion) that you are defending the hypothesis that scientific “evidence” is somehow suggesting that “chance” is the most logical explanation for the creation of the universe.

      I think that you are defending the idea that if we just keep dissecting and squeezing matter in every which way possible, then the “TRUTH” of how and why the universe came into existence is simply going drip out of it.

      So far, not so much.

      (Yeah, yeah, I know, more “poetry”)

      Anyway, with that being said, you are absolutely justified in defending the achievements of the sciences, for if it were not for quantum physics, we would not be having this conversation on an Internet.

      PhysicistDave wrote:
      “Keith also wrote:
      >the forms may ultimately exist as nebulous fields of energy and information.

      Keith, you like poetry, but using the poetic term "nebulous" changes nothing. Similarly, with the poetry you quote from Nick Herbert.”
      ----------------
      So, you’re going to parse my words?

      Remember, the only reason I brought up the term “nebulous” in the first place was in response to you saying that you see the “real” world. To which I tried (and failed) to get you to define what the word “real” actually means and applies to.

      Okay then, so tell me, what simple (layperson friendly) term would you use to describe the ontological status of matter just prior to the collapse of the wave function?

      Or how would you describe the alleged superpositioned status of an electron as it transitions (in accordance with Schrödinger’s equation) in the space between the slitted wall and that of the measuring screen in the double slit experiment?

      In other words, if you don’t think that the word “nebulous” is an accurate description of un-collapsed quantum waves suspended in a state of superposition,...

      ...then without resorting to some obscure jargon that only a physicist would know, let’s hear a word that you might use to describe (again, for the layperson) the indeterminate “fuzziness” of the quantum world.

      PhysicistDave wrote:
      “As I keep trying to tell you, Keith, there are more ways of viewing the world than are dreamt of in your philosophy!”
      ----------------
      Dave, you old and dusty bard, would you like to borrow my mirror, or do you have your own?

      I mean, the fact that you are a trained and devoted member of a profession that absolutely forbids any forays into world views that cannot be measured or tested via the scientific method, makes me wonder how you could miss the irony of your statement.

      Keith

      Delete
    12. Keith wrote to me:

      > I think (as per your own earlier assertion) that you are defending the hypothesis that scientific “evidence” is somehow suggesting that “chance” is the most logical explanation for the creation of the universe.

      Well, no, that is not what I said.

      I doubt that the universe was "created." And I also doubt that it came into existence at any particular time at all. Maybe the universe has been around forever: that is, after all, the (unproven, of course) hypothesis behind "eternal inflation." Who knows? Might be. Or not.

      You keep trying to claim that I have a position on questions for which my honest answer is: "Who knows?"

      I think you have trouble believing that there are human beings who really do not believe they have the answers to lots of these Big Questions. But I am one such human being. I know Feynman was another. I think Sabine might be willing to sign up for the "I don't know" club.

      Keith also wrote:
      >I think that you are defending the idea that if we just keep dissecting and squeezing matter in every which way possible, then the “TRUTH” of how and why the universe came into existence is simply going drip out of it.

      Nope. I think we may never know "how and why the universe came into existence." Maybe it never did come into existence.

      What I do think is that we know a lot about what has happened to the universe since shortly after the Big Bang, that there is no evidence at all that a Higher Intelligence was involved in all that, and that, as far as we can tell, it is explainable by natural physical laws, and, yes, chance. As always, I except human (and other animals') consciousness: right now, no one understands consciousness.

      Keith asked me:
      >Okay then, so tell me, what simple (layperson friendly) term would you use to describe the ontological status of matter just prior to the collapse of the wave function?

      I doubt that the wave function really collapses. I suspect (but certainly do not know!) that the truth is something like superdeterminism or Bohmian mechanics or temporally bidirectional causation or “annealing” of a block universe or whatever: none of these, as I understand them, requires a collapse of the wave function. We do not completely understand quantum mechanics.

      Anyway, the layman's term for what matter is before the "collapse of the wave function" is simply "matter." The electrons, protons, etc. are there: we are just arguing about exactly what they do.

      Keith also asked:
      >Or how would you describe the alleged superpositioned status of an electron as it transitions (in accordance with Schrödinger’s equation) in the space between the slitted wall and that of the measuring screen in the double slit experiment?

      Have I mentioned that I like to reply, "I don't know"?

      Bohmian mechanics gives one description; Edward Nelson's stochastic mechanics gives another, and I know of other viable theories that give still other answers. I don't know which of these, if any, is correct.

      Keith also said:
      >I mean, the fact that you are a trained and devoted member of a profession that absolutely forbids any forays into world views that cannot be measured or tested via the scientific method, makes me wonder how you could miss the irony of your statement.

      Glad you liked my misappropriation of the Bard of Avon! But my profession does not "absolutely forbid any forays into world views that cannot be measured or tested via the scientific method." We just do not take them altogether seriously.

      I hope it is becoming clear that modern science does not have a completed "world view" at all in the sense that you would like. What we do have is a much more well-validated partial world view than has ever existed before in the history of the human race. But that partial world-view may remain forever partial.

      Humans need to acquire the courage to say, "I don't know."

      Dave

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  9. They are better than mythologies because at least we can calculate things. If any phenomenology is wrong we can, at least in principle, find out what is wrong.

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  10. A good article on groupthink in science. The amyloid hypothesis monopolized research, alternate ideas were not funded or even allowed to be discussed at conferences. You seem to be alleging the same thing about physics, such as with strong theory and the multiverse. https://www.statnews.com/2019/06/25/alzheimers-cabal-thwarted-progress-toward-cure/

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  11. Sabine,

    Thanks for that concise overview, I must say that I respect Unicorn Cosmology more than its competitors; at least it specifies where its shit comes from.

    So here is the situation:

    1) LCDM is incapable of producing a coherent, not to mention scientifically viable, account of its "universe's" origin.

    2) The model requires, in its current account of the "universe", that 95% of the "universe's" total matter-energy content be composed of some undetectable "dark matter" and "dark energy", the only salient characteristic of either being that they each provide a necessary correction required to make the model agree with observations.

    Given that, isn't it time to at least reconsider this absurd model's foundational assumptions, in hopes of, perhaps, constructing a scientifically coherent account of the cosmos we actually observe?

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    1. "1) LCDM is incapable of producing a coherent, not to mention scientifically viable, account of its "universe's" origin."

      Prove that it is incapable. It hasn't yet. That doesn't mean that it can't. But then again, why should it? Why can't it do what it does well and there be some other explanation for the origin?

      "2) The model requires, in its current account of the "universe", that 95% of the "universe's" total matter-energy content be composed of some undetectable "dark matter" and "dark energy", the only salient characteristic of either being that they each provide a necessary correction required to make the model agree with observations."

      So what? Where is the problem? All theories which are viable agree with observations. You seem to think that there is a problem that human beings, who evolved to survive in the savannas of Africa, cannot directly perceive most of the universe. Why should they be able to?
      Given that, isn't it time to at least reconsider this absurd model's foundational assumptions, in hopes of, perhaps, constructing a scientifically coherent account of the cosmos we actually observe?

      "Given that, isn't it time to at least reconsider this absurd model's foundational assumptions, in hopes of, perhaps, constructing a scientifically coherent account of the cosmos we actually observe?"

      Be my guest. As George Efstathiou said, even if you have an alternative theory which does nothing more than explain current data as well as LambdaCDM, he will give you a job in Cambridge. I have no problem considering a better account, but I haven't found any yet.

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    2. @Philip
      What do you think of this: https://www.aanda.org/articles/aa/pdf/2012/01/aa16103-10.pdf
      It does explain a lot of things without DM or DE, and with fewer free parameters than LCDM.

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    3. They write: "antimatter is supposed to present a negative active gravitational mass". I don't think that this is true, and it might have been ruled out experimentally by now. If Steve Carlip reads here, maybe he can chime in. I also doubt that current type Ia supernova data (the paper is from 2012) are consistent with linear expansion.

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    4. Philip,

      Why can't it do what it does well and there be some other explanation for the origin?

      Why? Because your model predicts the origin which it can't explain. From a strictly logical perspective, that suggests that your model is very probably wrong in the assumptions that lead it to posit such an inexplicable but necessary state. Coupled with all the other undetectable (invisible) features of LCDM, I can't think of any rational excuse for believing in such an unscientific, nonsensical account of the cosmos. Which brings us to this:

      You seem to think that there is a problem that human beings, who evolved to survive in the savannas of Africa, cannot directly perceive most of the universe. Why should they be able to?

      I have to admit that got a laugh out of me. Are you seriously proposing, that I, a reasonably rational human being, should disbelieve my well-evolved and extremely useful, human senses (and their mechanical extensions)* and accept in their stead, the irrational musings of some nerd mathematicists who, on the basis of comments such as your's, couldn't frame a rational argument in defense of their belief system even, if the fate of their comfortable sinecures depended on it? You people really are delusional.

      * Parenthetical statement inserted to stave off diversionary pedantry

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    5. You understand neither LambdaCDM nor evolution nor basic logic.

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    6. You make my point, sir, that you are unable to frame rational arguments in defense of your beliefs. Perhaps this is because those beliefs have no rational basis.

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    7. @bud rap: You may have missed this: "As George Efstathiou said, even if you have an alternative theory which does nothing more than explain current data as well as LambdaCDM, he will give you a job in Cambridge."

      I've read a lot of comments by you, here in BackReAction. However, I have yet to read one which comes close to claiming that you have an alternative which is as good as the current set of explanations/models/whatever ... in terms of being consistent with the relevant observational (and experimental) results re cosmology.

      So, direct question: do you have such an alternative?

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  12. A not so true intelligible universe after all.....

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  13. "Then there is the possibility that the universe didn’t really “begin”"

    So it's fair to say that strictly speaking according to the empirical evidence it is not known that the universe had a beginning?

    "but these aren’t any better than traditional tales of creation. "
    But (some) speculative physical origin theories are written in terms of well-understood physical concepts so are at least meaningful; it is not inconceivable that Hawking's theory, say, could be empirically verified; and, the motivation of the theorists is to uncover the truth.
    In contrast, primitive creation tales are meaningless nonsense and it is not even known what it might mean for them to be true; and, they are used as the centrepieces of the biggest criminal frauds in human history, organised religions, where the motivation is to hide the truth so as to be able to control people.
    So there are those differences between the two.

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    1. "So it's fair to say that strictly speaking according to the empirical evidence it is not known that the universe had a beginning?"

      The answer to this question very strongly depends on what you mean with "begin" but if you mean "begin" as "origin of everything" the answer is, yes, it is possible that the universe didn't have a beginning, simply because it might have existed for infinitely long time before our theories plausibly apply.

      Creation tales were certainly meaningful for some people at some moment in history. Same with our theories for the beginning of the universe.

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    2. Sabine, some conditions before the so called big bang all hypothetical, and does not really matter in regards to the physical laws, nor can be really proven experimentally. At its best maximum indirectly. Same like string theory can not be proven, especially if string theory applies to the description of the vacuum, in regards to symmetry and symmetry breaking. The symmetry before phase transition can't be proven, not because it doesn't reproduce the standard model +gravity, but because there is no precise description of the transition itself, and in results, what laws or physical forces considerably emergent, if not all. String theory in its best, a description of some potential vacuum state before transition which is largely variable. String theory can be correct for such vacuum state, without the need to describe the current physics. And that's the problem of string theory, not that if its correct or not.

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  14. It may be boring but it is just great to hear someone say that there is no evidence base for any origin theory. There's a lot of people talking about highly speculative theories as if they were science "facts". Interesting, yes, evidence based science, no.

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  15. We must also consider the possibility that there is only a consciousness focused on an eternal moment representing the landscape that we consider Reality. It would take away many philosophical problems from above and is exquisitely simple and impregnable.

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  16. The do called big bang, considerably rather a point of phase transition from one system state into another, resulting in fixed physical laws and emergency of physics as we have today. All this nonsense about space and time began with the big bang, it's irrelevant completely,or rather create some mystified description tells nothing really.

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  17. I didn't see a mention of Phantom Energy, Cosmic Doomsday, where there would be a destruction of all matter, and then perhaps a steady state of recreation of matter as well. Since we are talking about creation theories. Robert R. Caldwell, Marc Kamionkowski, Nevin N. Weinberg discuss cosmic doomsday at https://arxiv.org/abs/astro-ph/0302506

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  18. For the universe to be cyclic I think it has to be a continuity, implying that the endogenous processes in the world aree continuous. I have no reason to think they are not.

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    1. I agree that there would be continuous creation and continuous destruction. Which would also mean continuous destruction of entropy.

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  19. There is a difficulty in knowing what is meant by the start of the observable universe and by any prior cosmos. In general it is not possible to extend the timelike direction of the observable universe, which to be conservative is a local direction, to a global frame. If the universe is a de Sitter spacetime the observable universe is one patch or chart on the manifold. It is not possible to extend the timelike vector field "here" to the second patch or chart.

    Inflationary spacetime may be deSitter and this obstruction fits with Velinkin's result that an inflationary spacetime has a finite past, even if it continues to a future infinity.

    The observable universe, within the inflationary phenomenology, is a bubble region where the large energy false vacuum has transitioned to a low energy vacuum. Time is generated by the Hamiltonian and even here it is not clear how time in this bubble, or pocket world, is translated to time outside in the inflationary spacetime. The different vacua across the boundary may be an obstruction to any translation of timelike vectors "in here" to "out there." The boundary had geometric information, think Gauss-Bonnett theorem, and these are "charges" that may obstruct any such extension.

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    1. Lawrence Crowell7:02 AM, December 28, 2019
      "There is a difficulty in knowing what is meant by the start of the observable universe"

      Is there a point t=0 (around 13.7 billion years ago) at which the structure of the universe is known, and such that it is meaningless to talk about the structure of the universe at any earlier t.
      Theoretically extrapolating backwards there is a point where space-time has no extent and mass and energy, etc., are theoretically infinite - a theoretical singularity. This is the theoretical beginning. Can it be physically described, and can it be shown that there is no describable universe at an earlier time to this.
      This is fairly obviously what is meant by a purported beginning of the observable universe.

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    2. The large energy false vacuum is a representative of one system state, so there is time parameter for that system. After transition you can distinguish the current physics including a time evolution from the transition point. What happened before should not be considered as timeless and all that nonsense. It's simple a different system state you can't determine due the fixed condition of the after transition state. Just my two cents.

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    3. You can say that 13.8 billion years ago matter and energy were in a much more dense and thus hot state. The time scale can be wound back for the local Hubble frame. However, once you get to quantum gravity things get odd. For one the meaning of time becomes uncertain. So whether our cosmos connects with some other space, say another patch in de Sitter spacetime is not clear. Even if so there is no general procedure for parallel translation of a time vector from one patch to another.

      Time really is local. Comologies are type O Petrov types, which means there is no global meaning to not only time but energy as well.

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    4. Lawrence Crowell4:30 PM, December 28, 2019

      Well, if time becomes uncertain that's a problem. But is the uncertainty physical or just theoretical? Is there a possibility that it could be shown that our spacetime didn't exist a second before some point, say, even if the nature of the first microsecond or nanosecond can't be nailed down?

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    5. The uncertainty in time intervals becomes important as they approach 10^{-37}sec or less. At time intervals larger, quantum states form a condensation of states we identify as space. As one were to probe to smaller time scales the meaning of space is lost.

      LC

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  20. Steven Weinberg: "there is an embarrassing vagueness about the very beginning... we would prefer a greater sense of logical inevitability about the theory...I cannot deny a feeling of unreality in writing about the first three minutes as if we really know what we are talking about." (1977, First Three Minutes). He reminds us that inflation at first attracted little attention and the whole idea of inflation remains pure speculation, though one that is increasingly plausible.(2008, page 202, Cosmology). A.D. Linde wrote: "we are witnessing a gradual change in the overall viewpoint in Cosmology." (1990, page 29, Inflation and Quantum Cosmology). James Peebles: "At the time this is written, the inflation scenario offers the only reasonably complete resolution of the puzzle of the large-scale homogeneity of the observable Universe." (1993, page 395, Cosmology). It is perhaps unfair to use research in Cosmology as an example of 'groupthink.' If that were so, James Peebles would have gotten his Nobel Prize many years ago. Instead, Cosmology is a rather difficult subject in which to correlate theory to observation. The survey of inflation in the 2018 Review of Particle Physics (pages 364-376) is a reflection of both modeling and experimental prospects. This is surely "better than traditional tales of creation."

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  21. Hi Sabine, I will give you my opinion, quite unauthorized by the way; but if all the baryons would disintegrate and cancel out with electrons, we would have a symmetric universe, the antimatter paradox would not exist; then there must have been a phenomenon in the past that twisted that symmetry; that phenomenon is asymmetric from the perspective of the current space, but it does not have to have implicit all the symmetric structure that we assign to it; in the end, the result will be a symmetric universe, extended and with Euclidean geometry; but it seems to come from a hyperdense universe, asymmetric from our perspective and organized in another type of geometry. I think it will be difficult to eliminate black holes from the very "beginning of the universe." Happy new year

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  22. I get irritated when people talk about "chance" and say that the universe couldn't have arisen by chance. First of all, what is chance? Do we understand it? Perhaps the dice are loaded because the only dice that can exist are loaded dice. Insufficient data in any case. Nobody is in any position to say that such and such couldn't have been the product of random events, even if we understood what a truly random event would be.

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  23. My understanding is that at t= Now the structure of the universe is physically understood (100 billion galaxies), and at t=Now -13,7 billion years the structure of the universe is physically understood (tiny, dense soup of quarks). But is there a point before that, t=0 that the structure of the universe is understood, but there is nothing before that - I don't think this is known.

    Creation tales weren't meaningful for some people. Some people were deluded in thinking meaningless tales meant something when they didn't. This is absolutely not the same as speculative physical origin theories. I think as a trained physicist you are making a fundamental mistake here. Failed theoretical physical theories are absolutely not the same as whacko delusional beliefs. Nobody is stabbing random people on London Bridge in the name of Hawking's theory of the origin of the universe. This is what the religious do. They are nutters.

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    1. Steven Evans,

      Failed theoretical physical theories are absolutely not the same as whacko delusional beliefs.

      When a failed physical theory is clung to by its believers despite the failure, the situation is functionally identical.

      As to this:

      Nobody is stabbing random people on London Bridge in the name of Hawking's theory of the origin of the universe. This is what the religious do. They are nutters.

      This is nothing more or less than a secular version of the very fundamentalist intolerance you claim to denounce. Tarring the vast swath of religious believers who peacefully inhabit this planet with the evil done by a demented few, is nothing but bullshit, and evil bullshit at that.

      And just for the record, mass murderers like Stalin, Mao, and Pol Pot are on the list of atheists, like yourself, who were/are vehemently intolerant of those with views contrary to their own.

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    2. But I don't support power-crazy, dogmatic ideologues whether communist or based on primitive fairy tales. You do. Of course dogmatic ideologies can lead to murder as you people have no argument. You ultimately have no choice but to force your delusional nonsense on people who aren't nuts like you.
      There is no such thing as an "atheist", because there is no such thing in reality as a god. By the standards of empirical science you are deeply, delusionally insane, I'm not, that's all.
      A natural scientist who clung to a theory that had been disproved by the evidence would be a crank by definition - see the crazy anti-vaxxers who where rightly struck off the medical record. In religion, it is the opposite - if you don't believe the evidence-free, lunatic dogma you get booted out of the organisation.

      "This is nothing more or less than a secular version of the very fundamentalist intolerance you claim to denounce."
      Is it? Where did I say delusional lunatics who believe in primitive fairy tales shouldn't be tolerated? I said that even throwaway, off-the-record comments suggesting these primitive fairy tales are anything but lunacy should be avoided by credible natural scientists, as loonies like you will jump on these comments and repeat them to support whatever oppressive, dogmatic, undemocratic, non-transparent, unaccountable, corrupt, criminally fraudulent, power-crazy, authoritarian, irrational, ideological, child-raping, gay-stoning, tax-dodging religion of love that you belong to. That was my point.

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    3. Steven Evans,

      For the record, I belong to no religion, nor do I have any religious sentiments regarding the possible existence of any metaphysical beings that might have influence over physical reality. My personal belief is that such beings do not exist.

      But having a strong background in science, I am well aware that I can provide no more evidence for the non-existence of such beings, than those who do believe can provide for their existence. Therefore, I find the question uninteresting - because unresolvable. I am neither a theist nor an atheist, I am an indifferentist regarding the subject of religion.

      What I object to here is your rabid intolerance for those who do hold religious views that differ from your own. The irrational, ranting, tone and substance of your comments here sit comfortably within the blood libel tradition. But, you say:

      ...I don't support power-crazy, dogmatic ideologues whether communist or based on primitive fairy tales.

      No, of course not. Clearly you do not wish to be associated with the mass murders of your fellow anti-religious fanatics. Unfortunately, you don't wish to extend such a courteous consideration to religious believers generally. For them, you exhibit only a broad and rabid intolerance.

      Where did I say delusional lunatics who believe in primitive fairy tales shouldn't be tolerated?

      No, you don't say it outright, because you don't have to. The technique is an old one. The "other" is first dehumanized ("delusional lunatics" who are members of "oppressive, dogmatic, undemocratic, non-transparent, unaccountable, corrupt, criminally fraudulent, power-crazy, authoritarian, irrational, ideological, child-raping, gay-stoning, tax-dodging religion"). From there it is but a short step to seeking a "final solution" to the problem presented by this sub-human population.

      You are a purveyor of evil drivel, sir. If there is a pseudo-scientific vein that is compatible with your unhinged views it is the same discredited one that sheltered the eugenicists.

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    4. But you write in defence of religion. Factually, to claim that religious beliefs can't be refuted is nonsense. The blog post explains how it is currently impossible to know whether the universe had a beginning or not, so anyone claiming to know otherwise is lying, probably to get money or power. Also, it is an empirical fact that humans in the Bronze Age had 1 human mother and 1 human father. To suggest otherwise because of a fairy tale written in a dusty, old scroll is moronic beyond belief. All the main tenets of all the religions can be similarly dismissed as empirically false and utter nonsense.
      The further problem with these whacko beliefs is that they are used as a basis for tribalism - the Buddhist Myanmerese soldiers murdering the muslim Rohingya; some Hindus now trying to deny non-Hindus rights as Indian citizens - and to abuse power - 1 billion Catholics fund and support the biggest paedophile ring in the world aka the Catholic Church.
      Organised "religion" is just a form of organised crime.

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    5. To Repeat:

      What I object to is your rabid intolerance for those who hold religious views that differ from your own. The irrational, ranting, tone and substance of your comments here sit comfortably within the blood libel tradition.

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    6. Except what I write isn't libel, it's true. Organised religions are based on criminal fraud, they are unaccountable, undemocratic, corrupt, etc.; the Catholic Church continues to commit child rape on an industrial scale; you will be stoned to death for gay sex or adultery according to Islamic law in Bandar Seri Begawan. And this is exactly how you would expect such unaccountable, corrupt power bases to behave. And the people who believe the silly fairy tales on which it is all based are morons. There is no escape from that conclusion.

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  24. Phantom energy occurs when the vacuum energy increases. I tried to work a phenomenology where this was a part of the universe as a time crystal. This has some plausibility. It implies the accelerated expansion of the universe will increase. At some point everything is torn apart, though paradoxically in a deep freeze.

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  25. Greetings. I work with complex ecological systems and climate change. So my comments here *should* have the credibility of the wine steward who told me he thought "it's the sunspots" when the topic came up of why the Earth is getting hotter, on average. So: (1) Inflation seems to me like a preposterous made-up answer to a problem. (2) CCC seems like someone working as closely to the scientific method as one could in a field in which we don't have any direct data (how the Universe began).

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  26. Layman's question: In various inflation models, is Gravity assumed to be an emergent property? I understand that General Relativity fails to describe anything back into the Planck Epoch, but at some point during the hypothetical inflation scenario, say about the point that baryogenesis occurred, why didn't the extremely dense mass of emergent matter cause the universe to collapse back into a singularity? Or do these theories assume that dark energy and/or the expanding FLRW metric somehow preventing things from collapsing?

    Apologies, if I inaccurately stated my question, but I think you get the gist. This question has puzzled me since I read Guth's popular book a couple of decades ago. And none of Physicist friends have been able to give me an answer (of course, none of them are cosmologists).

    —Wulf

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    1. Hi Wulf,

      No, gravity is not emergent in inflation. The reason it doesn't collapse back, in a nutshell, is that it expands too rapidly.

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    2. "No, gravity is not emergent in inflation. The reason it doesn't collapse back, in a nutshell, is that it expands too rapidly."

      Right, but this has nothing to do with inflation. In 1920s cosmology, still true today, whether the universe expands forever or collapses (or asymptotically approaches some state) depends on the values of the density parameter Omega and the cosmological constant lambda. If lambda is negative, the universe will always collapse. If lambda is 0, then it will collapse if Omega is greater than 1. If lambda is positive, then if the curvature (lambda+Omega-1) is negative or zero, then it will expand forever. If the curvature is positive, then it will collapse if Omega is greater than 1 and lambda is not to large, otherwise it will expand forever. (There are also models with positive curvature and positive lambda which expand after initial contraction to a finite radius, i.e. there is no big bang.) This is essentially the same as saying that it will expand forever as long as it is expanding fast enough.

      The above assumes that the universe is expanding now. Like most of physics, the equations are time-symmetric, so everything could also run in reverse. That the universe is expanding now depends on initial conditions; despite some claims to the contrary, one doesn't need inflation or anything else to make the universe expand.

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    3. Is spacetime emergent? In the context of quantum gravitation it may be.

      Inflationary cosmology is really a form of Brans-Dicke scalar-tensor gravity. Carl Brans and Robert Dicke laid down a scalar field theory, the same as taught in an elementary qft course, where there is an additional term with the Ricci curvature times the scalar field. The kinetic term with differentials of the field density act on spatial variables and is a sort of dissipation term. Physically this is where the scalar field is decaying into particles and radiation. The scalar field drives a rapid accelerated expansion of space, but where this decays. The best fit is a decay of 60 efolds, or an expansion of about 10^{26}. So a region of about 10^{10} Planck lengths in radius balloons into a volume about a meter in radius. This all happens in 10^{-33} seconds.

      In this system of basic inflation space and spacetime is essentially classical. This phenomenology gets an upgrade with eternal inflation, but still spacetimes is classical-like. The Ricci curvature though has the cosmological constant. This is a function of the scalar field. An interesting case with small spatial variation is where the cosmological constant is quadratic in the scalar field and you get a form of the cubic Schrödinger equation.

      It is really with quantum gravity that you get the prospect for emergence of spacetime. The nonlinear term with the cosmological constant bears similarities to a condensate physics, where spacetime may emerge from entanglements.

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    4. Erratum: I wrote wrong. If the cosmological constant is cubic intge field, the result is a cubic Klein-Gordon equation.

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  27. Jarek Duda wrote on 4:51 PM, December 27
    "How does second law of thermodynamics look like in cyclic models?"

    Jarek also noted the smaller volumes of space at the Big Bang and Big Crunch.

    In my speculative amateur opinon: in Penrose's CCC there are also fewer fermions near these two nodes. At the nodes themselves there are no fermions, only bosons in a condensate. The exclusion principle is consistent with conversion of bosons to fermions and the fermions require each and every one to be in a different state from each and every other; and different states means an increase in entropy after the BB.

    I have read previously somewhere else that it is hard to imagine a world where entropy is decreasing. Cups being formed out of shattered fragments etc. But fermions have an exclusion principle so this will not happen. In CCC the entropy decreases by the removal of fermions and turning them into bosons. That is the CCC does not have fermions aggregating themselves into fewer states. Bosons form condensates whereas fermions do not.

    But why should bosons turn into fermions after the BB and yet fermions turn into bosons preceding the BC? I imagine the turning point comes when the boson supply runs out or is too diluted in the expanded space of the universe at mid cycle. The second half of the cycle is supposed to take aeons and require fermions to annihilate similarly to BH evaporation.

    And why should the universe be reset from an infinite dispersal back to a single point? Well, this is the point that I like best. In my previous life, before retirement, I occasionally made psychometric metrics using the Rasch Model. At the end of a particular experiment, the analysis of the results kind of ignored the Rasch-ness of the scale, just analysing the data points using ordinary statistics. So that led me to generate pseudo random data to test how good the Rasch scale was at detecting true dispersions of points. The paper is available online. For some data a ratio-scale Rasch metric could not be calculated.

    Generated data which are dispersed remotely from each other and measured with no error are found to be impossible to put on a Rasch scale. This is well known in Rasch theory and the data are described as perfect Guttman data. In other words some error is necessary (and where would statisticians be without it). (Maybe) paradoxically, the more error in the data the better, and more finely divisible, is the metric, though only in the locality of the data points/fermions. Ironically, probabilistic Guttman data are the ideal data for the Rasch Model, yet perfect Guttman data kill it.

    The lack of the ability to make a metric prevents more fermions being created, while the dearth of fermions prevents the metric from being calculated.

    Finally, I watched two online videos by t Hooft yesterday where he talked of the universe being the fastest available calculator [G. Hooft - The hydrogen atom for quantum gravity, 2018]. So IMO even the universe as the fastest calculator cannot calculate a space metric when the data are on a perfect Guttman scale / too widely dispersed without an accompanying increase in error of measurement.

    -------

    Other points:

    I do not like the self-containedness of the CCC. IMO the start and end nodes of the CCC are like the creation and collapse of the wave function of a particle. And particles are often brought to a collapse at an interteraction with another particle. Maybe the universe needs an outside source to force collapse.

    With a universe ~ particle analogy, maybe there is an implication that an elementary fermion has an internal time dimension too. (Not my own idea.)

    I note that Lawrence Crowell suggested (my paraphrasing) that different bubble regions of space may have time arrows which are not inter-connectable. .... So could two time directions run in reverse directions without us being aware of it ...

    Also the CCC says nothing about the origin of the universe. Where did the first CCC node come from?

    Austin Fearnley

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    1. The de Sitter (dS) and anti-de Sitter (AdS) spacetimes are metrics defined in 5 dimensions. The imposition of a constant line element restricts the spacetimes of interest to 4 dimensions. For dS this additional dimension is spatial and for AdS it it time. So for the AdS there are two time directions, though the constraint restricts one away. Similarly for dS the additional spatial direction is restricted away.

      However, that is not quite how to see this. The Wheeler-DeWitt equation is similar to the Schrödinger equation, but without the right hand time evolution part. This comes from the Hamiltonian constraint in ADM formalism of general relativity. There is no general meaning to energy or time. This is because for general spacetimes there is no way to define a Gaussian surface to measure mass or energy. Only for spacetimes with a timelike Killing vector field can you do that. Petrov type-D solutions permit this, which pertain to black holes.

      However, one can introduce a scalar field that locally defines time by its quantum oscillations. So the possibly infinite dimensional Hilbert space of states is partitioned into finite sets according to how time is locally defined. This partitioning is related to what Jochen Szangelies writes with respect to horizons of observability. It also connects with integer partitions, such as the Hardy-Ramanujan function, that in turn enters into density of states in string theory.

      These partitioned sets then correspond to a subspace of states that can interact with each other. From a physical perspective this means any real observer can only access a finite amount of information about their observable world. This finitude of observation means there is an uncertainty concerning any concept of time and energy. In effect this partitioning is subjective, à la Bayesian statistics, and so any frame one defines time can never be global or universal.

      This is what happens when you spend lots of time pondering the mystery of time.

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    2. Lawrence

      Thank you for sharing your expertise. I have checked out your pointers but it will take some interminable time to grasp them!

      I have read that dS is more like our universe than is AdS. You say that AdS has two time dimensions whereas dS has only one. But I suspect that shape/curvature, rather than time, determines which is most acceptable, despite our universe approaching flatness? I also note that the Kaluza-Klein five dimensions have an extra space dimension rather than an extra time dimension. Jay Yablon last year put two very mathematical papers online in which he merged KK with Dirac equations and formed a composite five dimensional oblect which he calls DKK. (Six months ago he put a draft on s.p.r which I think you noticed.) His five dimensional space has two time dimensions. I further note that KK has not really taken off in leading to new findings and as not being identifiable with our universe?

      So purely with respect to the number of time dimensions, KK is similar to dS whereas DKK is siilar to AdS. However Jay notes that KK is not fully covariant whereas merging KK with D makes DKK fully covariant. Also Jay reckons his paper has halved the number of free parameters, with other finding too.

      The findings could be unreasonable effectiveness of mathematics in a toy universe explaining features of our universe, or maybe DKK is like our universe. Not sure how being fully covariant stands in this regard?

      Anyhow, Jay's papers are very mathematical, and although I have read them I am not in a position to comment seriously. But they do fit in with my own view of space and time(s). My preon model has electric charge being fully dependent on three colour charges (R, G and B) bt only at preon level and not at SM elementary particle level. The KK fifth dimension is supposed to equate to a dimension relating to the flow of electric charge. So for me that could be one electric time dimension (or more accurately for me, but not for Jay, three colour time dimensions).

      I think of a negative electric charge as motion in the electric time dimension and positive charge being movement against the electric time dimension. Or if one doesn't believe in moving against a time dimension then positive charge is like antimatter within the electric fifth dimension. OTOH the electric dimension could be a 4 dimensional object compactified into one dimension. And that compactified dimension could be spatial or temporal or a nasty composite? And in my colour model there could be 12 dimensions compactified into 3 colour dimensions which also cold be pure or a composite space & time in nature.

      Premsumable the maths in KK and Dkk does not allow one to pick a composite option. This affects brane theory too as IMO a red brane is really a red + antigreen + antiblue composite brane (or some multiple of this). In this way the relational properties of colour charges can arise.

      So can antimatter run backwards in time? Not according to most physicists posting on www physics forums. This could otherwise have been a problem for the origin of the universe as where did the antimatter go moving backwards before the origin? It is no problem for the CCC cyclic model as bosons can pass through the nodes. Except a problem for the very first cycle, maybe. In my preon model every elementary particle contains as many preons as antipreons. That means both particles and antiparticles travel equally forwards as backwards in the time direction of a Feynman diagram (even if not actually travelling backwards in time).

      Austin Fearnley

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    3. The dS and AdS are set in 5 dimension. The dS is a space in 4 spatial dimensions and one time. AdS is a subspace in 3 spatial and 2 temporal dimensions. The 5 dimensional line element is set to a constant. The resulting 4 dimensional spacetimes, 3 space plus time, are hyperbolic. The dS spacetime is topologically a single sheet surrounding the light cone. The AdS is one of a pair of hyperboloids inside the cones.

      The dS spacetime has two charts with separate coordinates, or separate coordinates systems that can't be extended to each other, where the inflationary space-time is one of these. The dS has topology R×M^3, for the real line being time and M^3 either a 3-sphere or Euclidean space. The AdS has topology S^1×R^3, where the circle S^1 is time. There are closed timelike curves. The AdS has negative constant curvature or cosmological constant. Negative vacuum energy, such as with the bosonic string, results in these curious conditions. The dS spacetime has positive curvature or cosmological constant.

      With the picture of hyperboloids the dS and AdS meet at asymptotic infinity. With the AdS_n ~ CFT_{n+1} this implies the field theoretic information of the two spacetimes. This then leads to interesting questions, because this has similarities to M-theory equivalencies between string types. The bosonic string, which is very attractive in ways, appears connected to the AdS and this would be equivalent to the field theoretic content of the dS. This is also suggestive of supersymmetry. However, the result of Vafa illustrates how superstrings are not consistent in dS, or that field theory in dS is not consistent with gravitation or quantum gravity.

      In some way the occurrence of classical spacetime restricts the quantum states on a physical vacuum. This means the occurrence of spacetime restricts what one observed of either quantum gravity or qft to lead to Vafa's contradiction and so called swampland.

      As for preons, with QCD the 1 to 10 MeV quarks are bound by gluons into the 938MeV protons. This means about 90% of the proton mass is due to QCD confinement. Without going into detail the IR confinement problem is formidable. The solution is asymptotic with lattice computations. Preons, which propose leptons and quarks are composites, mean a far more formidable renormalization group flow or confinement problem.

      I couldn't find Yablon, except as one of 800+ authors in LIGO papers.

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    4. Small erratum: I wrote: AdS_n ~ CFT_{n+1}. Instead this should be: AdS_n ~ CFT_{n-1}.

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    5. Hi Lawrence and Austin,

      Actually, the one of 800+ authors on the LIGO papers is my son Joshua. The paper of mine which Austin refers to has DOI: 10.13140/RG.2.2.10103.68007. Just paste that number into a browser and you will find it.

      Very briefly, if you take conventional Kaluza-Klein (KK) and use a Dirac-by-the-campfire deconstruction g_{mu nu}=.5{gamma^u, gamma^v} of their metric tensor into a set of five (u=0,1,2,3,5) linear gamma operators, you will quickly realize that KK is *not* generally covariant across all five dimensions. If you then reverse-engineer to require 5D covariance, the fifth dimension in the resulting Dirac-modified KK (DKK) flips its sign in the metric tensor, and becomes a second timelike, rather than a fourth spacelike dimension.
      From there, all of the conceptual problems in KK which stem from the extra spacelike dimension disappear. But also, the scalar field phi which KK use in the fifth dimension turns out to be a type of Higgs scalar which can be used in spontaneous symmetry breaking to give mass to the fermions. So in a surprising twist I never expected when I first started this paper, it is possible to explain all twelve fermion masses (including three generations of neutrino) entirely in terms of the CKM and PMNS mixing angles and a few other parameters including the Fermi G_F and Newton G constants (G enters into neutrino masses), cutting by twelve the number of *independent* natural parameters in the universe.

      Jay

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    6. It appears you are working with γ_5 = iγ_0γ_1γ_2γ_3 to define the KK dimension. This would I think connect with the weak interaction. The weak interaction is the Quantum Flavor Dynamic (QFT) gauge field, with three dimensions for flavors. I would then suspect this KK dimension is then the neutral weak current.

      Of course in general we could work with Γ_i, i = 1,2,...,10 or 11. As the "square root" of the metric one could also define curved spacetime and if the 3-space plus time directions are independent of these other dimensions this is thexyclicity of KK theory.

      With how you connect this to time it appears to be a "toggling" of CP, chirality and their violations, with T ( CP = T) so the parity violation of QFT is expressed equivalently with a time asymmetry, but with a second time.

      I am not sure how this would connect to AdS, with is embedded in a 5-dim spacetime with 2 time directions. The AdS is one of two hyperboloid sheets in the past and future light cones. The Dirac cones, in energy plus momentum are filled in the past cone. This is the old venerable "Dirac sea," and maybe this is tied to the asymmetry or parity violation.

      The physical spacetime we observe is more related to de Sitter, but the dS and AdS share the same field data at asymptotic infinity. So it is possible this CFT or QFT information holds in the observable universe.

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    7. Hi Lawrence, thank you for your taking a look and for your queries, I will reply here:

      I will refer to the pertinent equation numbers in DOI: 10.13140/RG.2.2.10103.68007.

      You say “It appears you are working with γ_5 = iγ_0γ_1γ_2γ_3 to define the KK dimension.”

      To be precise, I would say that I am starting the with conventional Kaluza-Klein (KK) metric tensors G_MN and G^MN (1.1) and following Dirac by asking what set of linear “square root” operators Γ^N can be *defined* to satisfy the anticommutator relation .5{Γ^M, Γ^N}==G^MN, which is (1.3). The goal is to make KK compatible with Dirac’s Quantum Theory of the Electron (call this the D&KK requirement). To make this occur, I require that these Γ^M *must* be a set of five (5) 4x4 operator matrices which transform 5-covariantly as a vector in five spacetime-plus-one dimensions. Because KK is not a flat spacetime-plus-one metric, I use a set of tetrads (vierbeins) e^M_a *defined* by the linear assemblage e^M_a γ^a == Γ^M, assuming γ^a to be the usual Dirac gamma, see following (1.3). Insofar as I can see, I make no other suppositions or assumptions. My goal from here is to be purely deductive.

      I find in sections 2 and 3 that the KK metric tensor is fundamentally incompatible with 5-covariant Dirac Theory. To make them compatible, three (3) changes are required: First, *even in ordinary spacetime alone*, the four-component gauge field A^u in the KK metric tensor *cannot* be a classical vector potential with four degrees of freedom, but *must* surrender two degrees of freedom and become a photon with two transverse degrees of freedom. That is, D&KK=DKK *requires* that the gauge field in the KK metric tensor *must* become a quantized, spin-1 photon, see (2.10) et seq. So, we have complexly fixed the gauge of A^u to that of the photon using no more than a symmetry requirement for general covariance in *ordinary spacetime*. Second, see (3.11) and (3.13), the G_05=G_50 component of the metric tensor must be equal to the scalar field psi originally postulated by Kaluza-Klein (which will later connect to the Higgs boson). Third, also in (3.11) and (3.13), the G_55 metric tensor component must be G_55=1+psi^2. This is what makes clear that the fifth dimension *must be timelike not spacelike*. That is, it is *impossible* for KK to be made compatible with Dirac theory if the fifth dimension remains spacelike. *We deduce this second timelike dimension*; we do not assume it. Once deduced, we can start to ask questions about anti-de-Sitter (AdS) spaces, etc., as you do, Lawrence.

      Then to complete things, in (4.20), (4.22) I calculate the inverse DKK metric tensor G^MN. And in (5.2) and (5.4) I calculate Γ^M and Γ_M respectively. We learn in (5.2) that in ordinary spacetime, G^mu = γ^mu + other terms. But uniquely, Γ^5= γ ^5, period, with no other terms. So, in answer to your query above, we deduce that Γ^5 is identical to the usual γ^5 = iγ^0γ^1γ^2γ^3. But, the lower-indexed Γ_5 in (5.4) is equal to γ _5 + another term. And no other component of Γ^M or Γ_M is equal to its corresponding γ^M or γ_M without additional terms.

      Then, once you have all of this, you can construct the Dirac-type equations (5.6) and (5.7) in configuration and momentum spaces, and can go “off to the races” exploring how the fermions of these equations, behave. That the scalar field psi which Kaluza-Klein first hypothesized can be turned into a Higgs field and give masses to these fermions which match the masses we observe in the lab, still has me pinching myself. And in my book, Kaluza and Klein were prescient, because they postulated the first “Higgs-type” field decades before it meant anything in particle physics. They just did not yet have Dirac’s theory, so had no basis for asking about Dirac-type five-dimensional covariance.

      Will hit character limit soon, so to be continued…

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    8. Lawrence, in reply continued (Part 2):

      You next say “this would I think connect with the weak interaction. The weak interaction is the Quantum Flavor Dynamic (QFT) gauge field, with three dimensions for flavors. I would then suspect this KK dimension is then the neutral weak current.”

      In one sense, I say, absolutely, yes! In another sense, I say maybe or maybe not. Because Γ^5= γ^5, and because 1+γ^5 and 1-γ^5 are used all over particle physical to extract two-component R and L chiral projections out of four-component Dirac spinors, and because any phenomena in nature which are not symmetric under chiral L<->R exchanges are rooted in weak interactions, I say absolutely, yes!

      On the other hand – and this is my personal bias which I will explain in a moment – I believe the correct way to generalize from the gravitational / electromagnetic unification which is implicit in KK and DKK, to weak and electroweak and strong interactions, is to use non-commuting Yang-Mills gauge theory to generalize the photon field A^mu into the three weak gauge fields W^mu 1,2,3, then combine these in the usual electroweak way to get the two W and the Z while retaining the photon. Then do similarly for strong interactions. And once you have a GUT gauge group – say some SU(N) – you are happy with and know all your stages of symmetry breaking to SU(3)_c x U(2)_w x U(1)_y then to SU(3)_c x U(1)_em, then you still generalize the same way. As a result, you *never* have more than five dimensions, three space and two time. You are simply adding N-dimensional Yang-Mills internal symmetry to DKK.

      You next say: “Of course in general we could work with Γ_i, i = 1,2,...,10 or 11.”

      Yes, you can always have more than five dimensions as a general mathematical proposition. The physicist’s question as I am sure you know, is whether you can get all of known physics into five DKK dimensions. If you can, then we have all we need and so should not add not one bit more. Of course, my DKK metric tensor (3.13) doesn’t give you all interactions, only electromagnetism embedded in a DKK gravitational metric tensor. But with the chiral properties of weak interactions are already inherent because you have Γ^5= γ^5 straight from the fifth dimension.

      As to the remaining interactions. because Yang-Mills gauge theory using various unitary subgroups has performed exceptionally well under a variety of circumstances, it ain’t broke so we shouldn’t try to fix it. Thus, as I said above, my bias is the take the gauge fields of DKK and generalize to other interactions using Yang-Mills, but with everything capped at five dimensions. Thus: five DKK dimensions, with Yang-Mills internal symmetry and symmetry breaking to capture all other (weak-beyond-chiral which we have from Γ^5= γ^5, and strong) interactions. I discuss this at length at pages 56-59.

      You next say: “As the ‘square root’ of the metric one could also define curved spacetime and if the 3-space plus time directions are independent of these other dimensions this is thexyclicity of KK theory.” I think you have a typo and I could not decipher the end of this. But from what I do understand here, I start the DKK derivation using KK’s (1.1) in “flat” spacetime in the sense that g_uv=eta_uv (Minkowski). Then when all is done at (3.11) we generalize eta_uv back to g_uv. So you really have two types of curvature: g_uv above and beyond eta_uv. And the entire DKK metric tensor G_uv above and beyond g_uv. Of course, in GR, “g_uv above and beyond eta_uv” captures the non-linearity of gravitation. I would think it continues to do so here.

      Will hit character limit soon, to be continued…

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    9. Lawrence, in reply continued (Part 3):

      You next say: “With how you connect this to time it appears to be a ‘toggling’ of CP, chirality and their violations, with T (CP = T) so the parity violation of QFT is expressed equivalently with a time asymmetry, but with a second time.”

      Yes, agreed. With CPT=1 and γ_5 = iγ_0γ_1γ_2γ_3, the usual C=iγ^2γ^0, the usual P=γ^5, and thus T=iγ^0γ^2γ^5.

      You say: “I am not sure how this would connect to AdS, with is embedded in a 5-dim spacetime with 2 time directions. The AdS is one of two hyperboloid sheets in the past and future light cones. The Dirac cones, in energy plus momentum are filled in the past cone. This is the old venerable ‘Dirac sea,’ and maybe this is tied to the asymmetry or parity violation.

      The physical spacetime we observe is more related to de Sitter, but the dS and AdS share the same field data at asymptotic infinity. So it is possible this CFT or QFT information holds in the observable universe.”

      I agree. Along these lines of how and what to “embed” into 5D DKK, it is worth considering the 5D Space-Time-Matter views advocated by the late Paul Wesson. See how I use this in (10.3) et. seq. to develop a “marble-not-wood” energy tensor. And, mirroring all of this but at the fermions' “square root” level, if I can call your attention to one more key equation, go to (11.2) and how this can embed the fermion rest mass into the Dirac-type equation (1.1) in the form of a “marble” Dirac equation (11.3) in 5D momentum space.

      Done. Thanks again!

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    10. Your response is in line with what I thought. That Gamma_5 = gamma_5 with no corrections seems in line with the cyclicity condition of KK theories. The correspondence with a gauge potential, maybe some equivalency between the space of representations of Dirac matrices and the moduli space of gauge fields, and a gauge field may be the "square root" of gravity. The Bern-Dixon gauge correspondence appears possible.

      Read the paper by Almhieri, Mahajan, Maldacena and Zhou on the Page curve of Hawking radiation. The Bekenstein bound works modulo quantum corrections. Those quantum corrections are given by a quantum entropy surface. This varies from the classical entropy bound with an additional topological freedom, say think of a principal bundle.

      The AdS_5 has causal wedges bounded by 4-dim surfaces. These surfaces may be AdS_4 or dS_4 depending on the sign of the Lanczos junction. This is a sort of 2 state system. In fact it has analogies with the Haldane chain and topological order. The "freedom" of these lower dimensional surfaces is a measure of the relative entropy between the classical horizon and the quantum entropy surface.

      For black holes the 4-dim BH has a degree of freedom relative to a 3-dim BTZ BH that is reflected in how BTZ relativity has no gravitational waves. This is then a departure where 4-dim BH has quantum information in gravitons.

      The BTZ black hole and 2 + 1 spacetime lacks the dimensions for helicity = 2 gravity waves. Yet this relationship between AdS_3 and AdS_4 <---> dS_4 may bear the property of gravitation as the square of a gauge field.

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  28. I see mainly 3 possibilities about evolution:

    1 - The present is completely determined by the past, or the past is entirely conserved: absolute repetition, novelty is not possible. No evolution as we know it.
    2 - The present is not completely determined by the past, or the past is not entirely conserved. Novelty is bounded but possible. Thanks to QM, I can breathe in such a universe!
    3 - The past is completely erased. Absolute novelty. The Big-Bang?? Can someone help me?;-)



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  29. "So, up to a temperature of about a TeV, we understand the physics of the early universe and we can reliably tell what happened. Before that, we have only speculation."

    Well, cosmic rays with PeV, EeV, and even ZeV (10^21 eV) energies have been detected. While those don't tell us much about particle interactions - like a super-duper LHC would - they are evidence that extrapolating the Standard Model (of particle physics, not cosmology) to ~ZeV is sorta OK. So while YMMV (your mileage may vary), I think it a bit harsh to say this is "only speculation".

    Gamma ray photons with energies well above what the LHC can produce have also been detected (~PeV from memory, but not yet EeV). Which is further evidence, related to the cosmic ray stuff, that the SM is likely OK for another three or so orders of magnitude at least.

    Sadly, nowhere near Planck scale, and in any case, astrophysical models of how such particles and photons are created aren't as easy to test as "testable with the LHC" models.

    A bit puzzled about this: "Well, we have zero evidence that the forces were ever unified". I thought there is pretty good, strong evidence that the electromagnetic and weak nuclear forces were once one? Isn't the electro-weak scale testable with the LHC?

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    1. Jean Tate,

      You are confusing energies in the restframe of the earth (which is what you quote) with energies in the center of mass frame (which is what I quote). Also note that a single collision does not make a plasma, so even saying that the LHC probes the early universe is a stretch. I am being very generous already.

      Grand unification refers to a unification of gauge groups to one group. It is not the same as electro-weak symmetry restoration, which, yes, happens at LHC energies of which the Higgs is evidence.

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    2. Ambiguous, sorry.

      Other than in the early universe (and fleetingly inside the RHIC and LHC, where something like quark-gluon plasmas may be made), where can one find high density/high energy conditions?

      In the hearts of neutron stars, especially "maximum mass" ones: observations don't help much; the equation of state of matter there depends on what models you prefer. Unlikely to beat the LHC though.

      In supernovae, especially core collapse ones: models are pretty good (i.e. consistent with observations); these supernovae can certainly produce TeV and PeV cosmic rays, but perhaps not TeV gamma photons. At least fleetingly "early universe" densities and energies, greater than RHIC/LHC ones, seem possible ... so some speculation, but not none.

      Kilanovae (i.e. NS-NS mergers): who knows? Observations are few, models rather unconstrained.

      AGN (active galactic nuclei): Observations are consistent with PeV photons being somehow produced there, and EeV and ZeV cosmic rays very likely originate there too (ditto the most energetic neutrinos Ice Cube has detected). However, the "how, exactly?" question has no really good answers yet. That said, "early universe" densities and energies likely exist, especially during flares, and they likely exceed RHIC/LHC ones by as many as six orders of magnitude. Some speculation, yes; but "only speculation"? I think that's an exaggeration.

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  30. Sabine, you write:
    “The purpose of the inflaton is to cause the universe to expand very rapidly early on, in a period which is called “inflation”.”

    Did the universe really expand very rapidly early in the beginning? Why is this assumed? It is assumed in order to explain the horizon effect. That means to explain, why areas in the early universe became very similar as visible in the CMB. And this necessary alignment took place at a time when these parts receded each other at such a high speed that, in view of the limited speed of light, a logical connection of these areas was not imaginable.

    So, this is a logical conflict between the extension of the space and the limitation of a possible information exchange. And this conflict was now solved by the assumption that the space was different, i.e. much smaller, than at later times. But why is this conflict not solved by the other parameter, the speed? Rather than assuming that the space was small and expanded rapidly later on, why not assume that the speed of light was extremely high during that time and decreased rapidly later on?

    Well, an Einsteinian will never accept that the speed of light can change. But is there any really strong argument for this? If we follow the Lorentzian relativity, a variable speed c is not a problem. So this change of c can be a solution for the horizon problem without the assumption of inflatons and other non-explainable phenomena. And this adds to other great advantages of the Lorentzian version of relativity; too many to name them here all. Just one point: The acceleration of the expansion is in the Lorentzian version a measurement phenomenon and not reality; so no need for Dark Energy.

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    1. antooneo asked:
      >Well, an Einsteinian will never accept that the speed of light can change. But is there any really strong argument for this? If we follow the Lorentzian relativity, a variable speed c is not a problem.

      If the speed of light changes in time in one frame of reference, then in another frame of reference the speed of light will be different in different places in space (since special relativity mixes space and time).

      Physicists have thought about this, but there is no evidence for it, and the speed of light is so intimately tied in to how the physical world operates, that any significant variation would tend to produce rather dramatic results! And there is no way to introduce this into existing theories in a way that seems very natural at all.

      To be sure, if anyone ever comes up with any evidence for such variations, physicists will take it seriously.

      By the way, this is one of the problems with the Lorentzian view that you are pushing: yes, indeed, a variable speed of light would fit so naturally into your view that one would rather expect it to see it! So, why don't we? Maybe because your Lorentzian view happens to be wrong.

      Note: I am not saying that your Lorentzian view is inconsistent: I'm just saying that the Einsteinian view predicts certain things to be true that are indeed true but that can only be explained as surprising coincidences under your Lorentzian view. Most physicists have decided to go with the approach that actually predicted what we observe in the real world -- i.e., what Einstein predicted but Lorentz did not.

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    2. Dave:
      There is a lot of literature of well-known physicists showing that the Lorentzian relativity is – regarding its results – fully equivalent to the version of Einstein. Just two names: S. J. Prokhovnik and F. Selleri. I refer you to their books and papers.

      Regarding the speed of light: If c is measured in different frames, then the result is always identical. This has a trivial explanation. If an observer changes to a different frame and measures the speed of light there, then the clocks and the rulers used change in relation to the original frame. It is a very simple mathematical exercise to show that the result of the measurement must be exactly the same. The calculation can be found in a lot of papers about this topic, but you will find the solution yourself.

      The change of clocks and the change of rulers follow from classical processes in physics and have been used e.g. by H. Lorentz and H. Poincare to explain the MM-experiment.

      If you, Dave, have any physical process in mind which is correctly explained by Einstein but not by Lorentz, please tell us here. I am confident to explain it for the Lorentzian way. That would not be my first time, I have done this exercise with high-level professors of relativity, and there was never a point left open. So please go on!

      There was an interesting letter exchange between Lorentz and Einstein in 1917. Lorentz explained Einstein a Gedanken experiment (a conductor around the equator with standing wave in it), the result of which can only be explained by the assumption of an absolute frame. Einstein fully agreed to the arguments of Lorentz and even added an own example for this. But then Einstein concluded that this absolute frame would be in conflict with his postulates and that these postulates had a higher priority for him than experiments. – Great philosophy, isn’t it?

      Why is an open discussion for this point is missing in the community? The above mentioned Franco Selleri told me once that he has found a very clear disprove of Einstein’s version of SR, but he would not be able to get it published by one of the known physical magazines. (And that’s true despite he was well known in the physical community for his publications also about quantum mechanics.)

      This reminds me a bit of a religion.

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    3. antooneo says:

      Well, an Einsteinian will never accept that the speed of light can change.

      Dave says:

      If the speed of light changes in time in one frame of reference, then in another frame of reference the speed of light will be different in different places in space (since special relativity mixes space and time).

      Physicists have thought about this, but there is no evidence for it, and the speed of light is so intimately tied in to how the physical world operates, that any significant variation would tend to produce rather dramatic results! And there is no way to introduce this into existing theories in a way that seems very natural at all.


      But who is more Einsteinian than Einstein?

      Einstein says:

      ...according to the general theory of relativity, the law of the constancy of the velocity of light in vacuo, which constitutes one of the two fundamental assumptions in the special theory of relativity and to which we have already frequently referred, cannot claim any unlimited validity. A curvature of rays of light can only take place when the velocity of propagation of light varies with position. Now we might think that as a consequence of this, the special theory of relativity and with it the whole theory of relativity would be laid in the dust. But in reality this is not the case. We can only conclude that the special theory of relativity cannot claim an unlimited domain of validity: its results hold only so long as we are able to disregard the influences of gravitational fields on the phenomena (e.g. of light).

      Observational evidence for Einstein's position:

      https://en.wikipedia.org/wiki/Shapiro_time_delay

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    4. John Bell wrote a paper "How to Teach Special Relativity," where he says "We have followed here very much the approach of H.A. Lorentz...the approach of Einstein is a difference of philosophy and a difference of style." (1976, see page 77 of Speakable and Unspeakable in Quantum Mechanics). Brown and Pooley later wrote a commentary upon Bell's paper, "The origin of the spacetime metric: Bell’s Lorentzian pedagogy and its significance in general relativity." (arXiv 9908048v2). The literature is replete with "open discussion in the community."

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    5. antooneo wrote: Lorentz explained Einstein a Gedanken experiment (a conductor around the equator with standing wave in it), the result of which can only be explained by the assumption of an absolute frame.

      That's inaccurate. Lorentz merely noted the well-known fact that the first-order Sagnac effect (for a waveguide cable circling the earth) is consistent with a stationary ether, although he agreed that it is also consistent with Einstein’s theory of relativity. Lorentz argued that Einstein’s relativistic interpretation is not the only possible one. Also, since we can detect absolute rotation, Lorentz argued that we cannot simply assume that it’s impossible to detect absolute translation. This (he said) can only be established by observation. Of course, he agreed that observation so far supports the principle of relativity, but he cautioned that “future observations may force us to abandon this hypothesis”. This is why he preferred to maintain the ether interpretation, in case violations of Lorentz invariance were ever discovered.

      Einstein fully agreed!

      Not at all. Einstein, writing in a conciliatory way to Lorentz (who he revered), went so far as to say that one could refer to the spacetime metrical field as “the ether”, especially in general relativity where the metric becomes a dynamical element of the theory. However, “this new ether theory would not violate the relativity principle any more, for the state of the guv=ether would not be that of a rigid body in an independent state of motion”. He went on to correct Lorentz’s scenario, by mentioning that the metric field in the vicinity of the rotating earth would actually not be perfectly stationary (as Lorentz supposed), but would rotate, albeit very slightly… referring to what is now called the Lense-Thirring effect.

      He gave an own example saying: The Foucault pendulum is not understandable without the existence of an ether.

      He said no such thing. He merely pointed out that, because of the Lense-Thirring effect, Focucault’s pendulum would also precess, by about 0.01”/year, and lamented that it was too small to measure.

      But then he added: I can anyway not except an ether because it is in conflict with a principle my theory is based on.

      No, what he actually said was “I prefer the guv [metrical] interpretation to an incomplete comparison with anything material [i.e., Lorentz’s ether]”. He explained his view of this much more fully in the famous Leiden lecture a few years later.

      So Einstein has clearly neglected observable facts which contradict his theory... This reminds me a bit of religion.

      There is no mention in these letters, either by Lorentz or Einstein, of any observable facts contradicting Einstein’s theory.

      Franco Selleri told me once that he has found a very clear disprove of Einstein’s version of SR...

      Selleri was known for his campaign to convince the world that the simple Sagnac effect disproves special relativity. He was mistaken.

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    6. antooneo wrote to me:
      >There is a lot of literature of well-known physicists showing that the Lorentzian relativity is – regarding its results – fully equivalent to the version of Einstein.

      I'm well aware of that, antooneo.

      The problem is that Lorentz himself was working solely with electromagnetic theory in which, yes, you get the "universal speed limit" and, of course, the Lorentz transformation simply from Maxwell's equations. For electromagnetic theory alone, Lorentz and Einstein do indeed give the same results (Einstein was of course well aware of this).

      The problem is that, in the Lorentzian approach, there is no reason that the same universal speed limit should apply for the other forces: gravitation and the strong and weak forces.

      If the OPERA claims on faster-than-light neutrinos had panned out, that would actually have been a big boost to the Lorentzian approach and strong evidence against Einstein: different speed limits for different forces would have been easy to accommodate in the Lorentzian approach (neutrinos of course do not "feel" the electromagnetic force).

      And, that is precisely why we "Einsteinians" figured that the OPERA results were almost certainly in error: unlike you Lorentzians, we have postulates that require the same universal speed limit for all forces.

      We believe in the Einstein approach because again and again and again, tests have been done that could have easily disproven Einstein, and thereby shown that the Lorentz approach was superior.

      And each time, Einstein won. Again and again and again.

      antooneo also wrote:
      >Regarding the speed of light: If c is measured in different frames, then the result is always identical. This has a trivial explanation. If an observer changes to a different frame and measures the speed of light there, then the clocks and the rulers used change in relation to the original frame. It is a very simple mathematical exercise to show that the result of the measurement must be exactly the same.

      Yes, antoonero, I, and anyone interested in the history of physics, know how Lorentz's analysis worked. The problem is that Lorentz had no reason to assume that the same symmetry that applied to electromagnetism also applied to all other forces.

      Einstein's innovation was to postulate that the Lorentz symmetry applied to all physical phenomena, not just electromagnetism. That postulate has stood up well to observational tests.

      antooneo also wrote:
      >There was an interesting letter exchange between Lorentz and Einstein in 1917. Lorentz explained Einstein a Gedanken experiment (a conductor around the equator with standing wave in it), the result of which can only be explained by the assumption of an absolute frame

      You are wrong. What you have said is not the truth.

      I know you are wrong because earlier you claimed that "Lorentzian relativity is – regarding its results – fully equivalent to the version of Einstein." One of your statements therefore must be false.

      QED.

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    7. By the way, antooneo, provide us the link to your claim about the conductor with the standing waves, and perhaps someone will take the time to explain it to you. Perhaps your misunderstanding is due to the fact that there is no inertial frame in which the entire equator is at rest: the earth's rotation of course involves acceleration and opposite sides of the equator have different velocities, and you can only use special relativity in inertial frames. Or perhaps you are simply confused by the fact that a standing wave in one frame of reference looks like two traveling waves, of different wavelengths and frequencies, in another reference frame.

      Both of these effects are very well understood and have been for a very, very long time. And, yet, one crackpot after another keeps claiming to have disproven relativity simply because he does not understand non-inertial motion. The one I was most familiar with was an engineer named Peter Beckmann.

      In any case, as I said above, you yourself cannot have it both ways: you cannot have it that Lorentzian theory gives exactly the same results as relativity, that Lorentizain theory is true, and yet claim to have a counter-example that proves that relativity is false! You contradict yourself, which is how we can be sure that something you say is false.

      antooneo also wrote:
      >Why is an open discussion for this point is missing in the community? The above mentioned Franco Selleri told me once that he has found a very clear disprove of Einstein’s version of SR, but he would not be able to get it published by one of the known physical magazines. (And that’s true despite he was well known in the physical community for his publications also about quantum mechanics.)

      Franco who??? I have honestly never heard of the guy. If he really had something that disproved relativity, he could have published it on the Web. If he considered himself a scientist and honestly thought he had a disproof of relativity and yet did not publish it even on the Web... Well, if your story is true, this guy was dishonest and it is good that most physicists do not know who he was.

      You end by saying:
      >This reminds me a bit of a religion.

      Well, we have evidence: Einstein's postulate, not made by Lorentz, that all forces of nature obey the Lorentz symmetry, has been tested again and again. Einstein has been confronted with the evidence and has prevailed. Not usually how religion works.

      By the way, your guy Prokhovnik in his paper "The Physical Interpretation of Special Relativity - a Vindication of Hendrik Lorentz" quotes Lorentz as saying, “Einstein simply postulates what we have deduced, with some difficulty and not altogether satisfactorily, from the fundamental equations of the electromagnetic field." Again, precisely what I have been trying to hammer into your head: Lorentz's analysis only applies to “the electromagnetic field,” not to any interactions at all that occur in nature.

      While Prokhovnik gets a number of points wrong (if he were my student, I'd flunk him!), he does make the core point I have been trying to get through to you:
      >”[Einstein} deduced a new composition of velocities formula, confirmed the invariance of Maxwell's equations under a Lorentz transformation, and proposed audaciously to modify all the laws of mechanics as well as of electrodynamics and optics to make them similarly invariant.
      ...
      “It is seen that Einstein's contribution heralded a veritable revolution in our ways of observing nature and describing the physical laws of nature, and it had a number of other consequences..”

      I bolded the key point I have been trying to get through to you: Einstein “proposed audaciously to modify all the laws of mechanics as well as of electrodynamics and optics to make them similarly invariant.

      That is indeed the key difference between Einstein and Lorentz, and Einstein has turned out to be right.

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    8. bud rap asked:
      >Einstein says:
      >"...according to the general theory of relativity, the law of the constancy of the velocity of light in vacuo, which constitutes one of the two fundamental assumptions in the special theory of relativity and to which we have already frequently referred, cannot claim any unlimited validity. A curvature of rays of light can only take place when the velocity of propagation of light varies with position. Now we might think that as a consequence of this, the special theory of relativity and with it the whole theory of relativity would be laid in the dust."

      Well, as the saying goes, it's relative.

      If you choose to measure velocity by local physical coordinates, using a good local clock and good local measuring rods, (i.e., a locally Minkowskian coordinate system), you will always in GR measure the speed of light in vacuo as the well-known 299792458 meters per second. That is a basic postulate of GR and is implied, obviously, by the equivalence principle.

      But, of course, you do not have to measure time with local clocks. For example, when you are considering the speed of light near the sun, you can choose to use, for your time measurements, clocks far away from the sun. Because of gravitational time dilation, clocks near the sun measure less time having passed than clocks far away. Of course, that means you then will calculate a slower speed for light near the sun than someone using time measurements from a clock near the sun.

      Of course, in practice you do have to use distant clocks since an ordinary clock placed near the sun would melt!

      I think most physicists nowadays would probably choose to deal with time as it would be measured by a nearby clock, so Einstein's discussion is a bit outdated, but it is not wrong: it's just... relative.

      By the way, Einstein's way of thinking about this can indeed be a simple way ((in fact the way I myself prefer) of showing how not only light but also "matter waves" bend in a gravitational field. But, of course, you do not have to view it that way: I myself know at least three other ways of solving the problem which will, of course, give the same answer.

      But you do have to do the math consistently and correctly.

      Now I know, old friend bud, that your response will basically be "But Einstein's words say... but Einstein says..." which is why I and others keep lecturing you on the need to learn the math. Words can be ambiguous, but the math, if done right, is not.

      I am also aware that various crackpots play this "words only" game to argue, "Sometimes physicists say that time runs more slowly deep in a gravity well, and sometimes physicists say the frequency of light is lower deep in a gravity well, and so which is right?"

      Again: it is the same thing. You can choose whichever set of words you choose, they are just attempts to put the math into English. But the math does not have two conflicting effects, just one.

      The Book of Nature is indeed written in the language of mathematics. You don't like that? Complain to Nature, not me.

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    9. Hi All,
      this is a great response to the original point of relativity. I am going to answer everything that addresses me, but one after the other.

      But first priority now is our local New Year's Eve party.

      And I wish Sabine and all participants here a very happy New Year.

      Delete
    10. 1) The difference between the relativity of Einstein and of Lorentz:

      Einstein has described the relativistic reactions mathematically. He has based his system on postulates. Lorentz in contrast has deduced relativity from basic physical facts. This different approach has an analogy with astronomy. Kepler has once described the planetary motion mathematically and has given us Kepler’s rules also as postulates. That is somewhat analogue to Einstein’s action. Later Newton has deduced Kepler’s rules from basic laws, the law of gravity and the law of inertia. This is analogue to the way of Lorentz.

      I think that we all agree that the way of Newton was a great progress compared to Kepler. Because it showed the causes, and phenomena like the mutual influence of planets was only understandable with Newton, not with Kepler. And this is as progress works in physics.

      Similarly, Lorentz deduced the relativistic reactions from basic physical laws. And the result is not only the same Lorentz transformation, but this way yields further physical insights which are not available from Einstein. All experiments using the Lorentz transformation confirm both versions, the one of Einstein and the one of Lorentz, but Lorentz does more. As an example, the internal oscillation with c going on in all elementary particles, which Lorentz used to explain dilation, was a new information about the structure of elementary particle, which is meanwhile an accepted element of particle physics. Einstein’s relativity quite naturally does not yield such insights. And we have the well-known open problems in present physics as are Dark Matter and Dark Energy, which have a solution with Lorentz, not with Einstein.

      What about the “electromagnetic” relativity of Lorentz? Lorentz has deduced the phenomenon of contraction from the known behaviour of forces. However, the only polar force known at that time was the electric one. So, he could only refer to that one. Meanwhile we know more forces, particularly the strong force, and it is understood that also this force and any others have this behaviour. Einstein’s corresponding saying that “space” contracts, covers all of it but is not based on any physics. Like Kepler’s rules.

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    11. 2) Measured constancy of the speed of light:

      The basic method to measure the speed of light is the one-way measurement, where one needs two clocks, one at the beginning and one at the end of the measurement distance. These clocks have to be synchronized appropriately, that is essential. And Einstein has given a rule how to perform this synchronisation: One has to send a light signal from the one clock to the other one and a light signal the way back. And with the assumption now that light propagates equally into any direction, an alignment of the clocks is to be done.

      Now, if clocks are synchronized in this way, the subsequent measurement of c must always yield the same result. That is, because this measurement of c is exactly the same process as the synchronization before. So, the measurement must logically reflect the assumption used in the synchronization.

      What Einstein does here, is a standard case of circular reasoning. And it is interesting that Einstein was aware of this fact. He makes a corresponding remark in his famous paper of 1905. But he assumed that, despite of this, the result might be a good one.

      As a summary we must say that this constancy of c in all frames is not a property of nature but a property of Einstein's synchronization.

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    12. Einstein has described the relativistic reactions mathematically. He has based his system on postulates. Lorentz in contrast has deduced relativity from basic physical facts.

      Lorentz and Einstein both described things mathematically, both based their descriptions on facts, and both postulated physical principles. It’s a myth that Lorentz deduced the Lorentz invariance of mechanics. True, he mistakenly believed (in 1904) that all mass was electromagnetic in origin, but that belief that never made any sense (as was clear to Einstein from the start). When Lorentz finally realized this (by the time he wrote his 1909), he recognized that he simply had to assume (postulate) that mechanical inertial and any other forces are Lorentz invariant… just as Einstein did. Of course, this is not an unfounded principle, it is forced upon us by the experimental facts. You can read about this in any good book on the foundations of relativity.

      Kepler has once described the planetary motion mathematically… somewhat analogue to Einstein’s action. Later Newton has deduced Kepler’s rules from basic laws, the law of gravity and the law of inertia. This is analogue to the way of Lorentz.

      You seem to use the phrase “described mathematically” in a perjorative sense. Physicists describe things mathematically. Also, please note that Einstein modified and corrected Newton’s fundamental laws of inertia and gravity, so your analogy makes no sense.

      [Lorentz’s] way yields further physical insights which are not available from Einstein.

      To the contrary, the subsequent history of physics (e.g., general relativity, the Dirac equation, etc.) has shown the trememdous heuristic value of the relativistic approach, whereas it was already clear by the end of the 19th century that the material ether concept had run out of heuristic value, and indeed had become a hindrence.

      All experiments using the Lorentz transformation confirm both versions…

      Well, if we define the neo-Lorentzian theory as simply special relativity combined with a semantic commitment to calling one particular system of coordinates the “true” coordinates, then yes, they are empirically indistinguishable, because that semantic commitment is empirically meaningless (as well as hypocritical, since it can’t be done in practice, as Lorentz himself admitted).

      The internal oscillation with c going on in all elementary particles, which Lorentz used to explain dilation, was a new information about the structure of elementary particle, which is meanwhile an accepted element of particle physics. Einstein’s relativity quite naturally does not yield such insights.

      To the contrary, all the labor of the Maxwellians and Lorentzians to infer the structure of the electron turned out to be misguided and fruitless, whereas the Dirac equation (which led to the modern understanding of elementary particles) was solidly based on reconciling the quantum equation of particles with special relativity. This is perhaps the prime example of the heuristic value of special relativity.

      And we have the well-known open problems in present physics as are Dark Matter and Dark Energy, which have a solution with Lorentz, not with Einstein.

      You’re alluding to a “fact” not in evidence.

      ...if clocks are synchronized in this way, the subsequent measurement of c must always yield the same result... What Einstein does here, is a standard case of circular reasoning.

      That’s another myth. Inertial coordinate systems (i.e., “systems in which the equations of Newtonian mechanics hold good” in the low speed limit) are defined based purely on the isotropy of mechanical inertia. The fact that the speed of light (or any massless energy) is isotropic and equal to c in terms of these same systems of coordinates is not circular. It implies that any energy E has inertia corresponding to E/c^2, from which it follows that inertial coordinate systems are related by Lorentz transformations. Again, you can read about this in any good book on the foundations of relativity.

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    13. Dave,

      You are a clever little fellow. You think you know what my response will be before I make it. Well here it comes Dave, let's see if your knowledge of the future is any better than your knowledge of physics.

      First of all, I want thank you for providing me the opportunity to address a pet peeve of mine, this deliberately misleading and false statement:

      If you choose to measure velocity by local physical coordinates, using a good local clock and good local measuring rods, (i.e., a locally Minkowskian coordinate system), you will always in GR measure the speed of light in vacuo as the well-known 299792458 meters per second.

      The speed of light in the cosmos is not a constant. That is an empirically based statement of fact. It is not disputable. The response you have to this, that if you could do something that you can't do, which is to hunker down in the vicinity of the sun or other similarly strong gravitational field, and under very contrived and constrained circumstances, measure, in the vicinity of your navel, you would find, "...the speed of light in vacuo as the well-known 299792458 meters per second."

      There are three things wrong with this argument:

      1) It is a non sequitur, it does not meaningfully address the factual statement it pretends to respond to.

      2) It is a thought experiment which has little likelihood of being implemented in the foreseeable future and the claimed result that would ensue, is only a dubious theoretical expectation.

      3) The expected result of the thought experiment (the SR speed of light 299792458 m/s), is not an observed constant. No consistent observation of that value has ever been achieved here on earth. That value for the SR constant c was declared by fiat in 1983.

      In essence, what you are doing, is analogous to responding to the factual statement that the earth is round with the irrelevant comment that your backyard is flat. Note that the response doesn't actually say the factual statement is incorrect, but it is presented so as to appear to be a refutation.

      This disingenuous approach to the question of the variability of light speed, is not, of course, novel to you. It's been deployed for years for the purpose of obfuscating an inconvenient, empirical fact. No doubt you absorbed it, without reflection, back in your impressionable school years.

      Dave says: Words can be ambiguous, but the math, if done right, is not.

      and Dave says: ...But, of course, you do not have to view it that way: I myself know at least three other ways of solving the problem which will, of course, give the same answer.

      The second statement falsifies the claim of the first that math is not ambiguous, at least in its descriptions of physical processes.

      Words can, indeed, be ambiguous and imprecise, to the extent of being an almost meaningless babble, for instance:

      The Book of Nature is indeed written in the language of mathematics. You don't like that? Complain to Nature, not me.

      Einstein, on the other hand wrote carefully, unambiguously, and precisely in almost all cases:

      We can only conclude that the special theory of relativity cannot claim an unlimited domain of validity: its results hold only so long as we are able to disregard the influences of gravitational fields on the phenomena (e.g. of light).

      So, words are not inherently ambiguous and imprecise. They clearly are so, however, in the hands of people like you, whose thinking processes are befuddled by a pernicious belief in mathematicism.

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    14. antooneo wrote to me:

      >The difference between the relativity of Einstein and of Lorentz:
      >Einstein has described the relativistic reactions mathematically. He has based his system on postulates. Lorentz in contrast has deduced relativity from basic physical facts."

      Nope.

      The calculation that Lorentz did can, of course, just as easily be done by someone taking Einstein's approach.

      A basic idea of Einstein's approach is that you can choose whichever frame of reference you wish in which to do a calculation. So, of course, "Einsteinians" can (quite arbitrarily!) choose one frame of reference, announce that they will label it "the absolute rest frame," and do all their calculations in that frame, just as Lorentz did.

      Of course, it is more than slightly foolish to insist on this, since there is no possible way to know if you have chosen the "true" absolute rest frame and since often the calculation is easier if you choose a different reference frame.

      antooneo also wrote:
      >As an example, the internal oscillation with c going on in all elementary particles, which Lorentz used to explain dilation, was a new information about the structure of elementary particle, which is meanwhile an accepted element of particle physics.

      What on earth are you talking about?? What do you mean by "the internal oscillation with c going on in all elementary particles, which Lorentz used to explain dilation... which is meanwhile an accepted element of particle physics."??

      I realize that there are some eccentrics out there (e.g., Albrecht Giese) who are pushing some bizarre theories along these lines, but their theories most assuredly are not "an accepted element of particle physics"! Nor, as far as I can tell, were these theories used by Lorentz! Are you just making this up?

      antooneo also wrote:
      >What about the “electromagnetic” relativity of Lorentz? Lorentz has deduced the phenomenon of contraction from the known behaviour of forces. However, the only polar force known at that time was the electric one. So, he could only refer to that one. Meanwhile we know more forces, particularly the strong force, and it is understood that also this force and any others have this behaviour.

      Except the person who actually laid down as a basic postulate that all the other forces, aside from electromagnetism, that might turn up must show the appropriate relativistic symmetries was NOT Lorentz but Einstein.

      Einstein 3, Lorentz 0.

      antooneo also wrote:
      >Einstein’s corresponding saying that “space” contracts...

      Except what relativity says is not that "space" contracts but that objects in motion contract, and, as you keep reminding us, Lorentz said the same thing and indeed showed why this must happen if all forces are electromagnetic. Einstein agreed.

      Contraction of length (not space!) is real. It does happen.

      antooneo, you are just making stuff up, such as suggesting that Albrecht Giese's bizarrely eccentric ideas are "an accepted element of particle physics."

      You need to stop doing this: honesty really is the best policy.

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    15. Well I feel obligated to point this out again - the speed of light has nothing to do with light as such. It's a structural element of spacetime geometry, and it is 1. In Riemannian geometry, the length scale is global, so if it is 1 here, it is 1 everywhere by continuation. There is no such thing as a variable speed of light. There is such a thing as a non-Riemannian manifold.

      The above was an interesting discussion.

      -drl

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    16. The OP asked "Well, an Einsteinian will never accept that the speed of light can change. But is there any really strong argument for this?" and the answer is YES, a conclusive one. The great thing about conclusive arguments is that they stop the arguing :)

      -drl

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    17. @bud rap: you wrote "The speed of light in the cosmos is not a constant. That is an empirically based statement of fact. It is not disputable."

      I'm curious: for you, what are the experiments and/or observations (empirical by definition) that establish the "fact" that the "speed of light in the cosmos is not a constant"?

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    18. This discussion has confused me and I hope someone clarifies my beliefs. For me, what underlies Einstein's theory is that space is a physical reality that you cannot skip; it takes time in terms of physical fields to go from one point to another; the nature of space and fields seems to be the same; this means that the measurements that some people make from Jupiter, Saturn, Tuesday and Uranus on the distance between the Earth and the Moon are relative and only agree that the speed of light is the same; there is no other way to reconcile all measurements; it is impossible to think that if a star moves in the constellation of Orion, I may die because my house reduced its dimensions and crushed me; or because a rocket moves at speed C will change the time of the rest of the universe; It only changes its own time. We continue, because the fields when they are energized or non-energized change their wavelength and their frequency but not their speed, they become the best rule of measure that exists. Note that if we took pure space it was only a rigid spatial measure; but being involved a field dynamic becomes a metric spacetime Ah! ; but if everything is made of fields; then we must reconcile the other facts with this rule; it is there that Einstein establishes the agreement between an accelerated system and another exposed to the gravitational field; So the field source curves that metric space-time proportionally. Never before has the philosophical intuition that reality is a physical fact and a scientific theory so agreed; am i too credulous?

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    19. 3) Relativity and rotational motion

      It is an old question whether rotation can be defined in the relativistic world of Einstein, which means here without the assumption of some kind of an ether. Mach and Lorentz denied it. There was some discussion between Mach and Einstein and they did not reach an agreement. Lorentz presented Einstein in 1917 his Gedanken experiment with a standing wave around the equator (mentioned earlier) where the interference nodes do not move with the earth. Question is, in relation to what the nodes behave.
      Einstein responded initially with an appreciation of Lorentz’s thought:
      “I was amused that you have considered exactly the same example that went through my head often in the past few years.” Then he says: “If the earth did not exist or did not rotate, the interference nodes of ring I and II would remain at rest in relation to the “fixed stars” and also in relation to each other.” Here Einstein mentions the idea of Mach about the fixed stars background to have a reference for circular motion, which without such reference cannot be defined. Then Einstein mentions the gravitomagnetic effect, which has a tiny influence on the interference nodes, but which is also in the mind of Einstein no explanation for the reaction of the nodes discussed. In addition Einstein mentions here the Foucault pendulum, where Einstein regrets that it also shows nothing than a gravitomagnetic influence. - Here Einstein has no solution.

      In 1920 in his lecture in Leiden he believes to have a solution. He sets the ether of Lorentz apart from the ether of Mach and finds
      “Mach’s ideas find their full development in the ether of the general theory of relativity.” He then says that his field elements guv can be set into relation to Mach’s fixed star background. -
      In this case rotational motion can indeed be defined. But Einstein’s bind of these guv to this background defines a fixed frame, and so Einstein gives up his most basic idea, the abstinence of just this fixed frame. - And up to today there is no solution for this conflict.

      Another conflict with an ether-free relativity is the Sagnac experiment. This was repeatedly discussed with the result that there is no conflict. But this harmless result only applies if the Sagnac process is viewed by an observer at rest. For a co-moving observer there is a clear conflict, because in his system the speed of light has a different value for the direction with or opposite to the rotation. Very well visible with the device “Laser Gyroscope” used these days in navigation system. The argument that this is a rotational motion and so SR not applicable can be circumvented by extending the diameter of the Sagnac circuit to infinity. In that case there is a continuous transition to a linear motion, but the difference of the speed in both directions will not diminish during the transition.

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    20. bud rap wrote to me:
      >Dave says: Words can be ambiguous, but the math, if done right, is not.

      >and Dave says: ...But, of course, you do not have to view it that way: I myself know at least three other ways of solving the problem which will, of course, give the same answer.

      >[bud]The second statement falsifies the claim of the first that math is not ambiguous, at least in its descriptions of physical processes.

      No, bud, the fact that I know several different methods to calculate an answer that all give the same answer does not make the math ambiguous: quite the contrary, it is evidence that the math is unambiguous.

      Look: I can think, off the top of my head, of at least four ways to multiple 79 times 81. They all give the correct answer: 6399 (yes, I can easily do that in my head with one of the methods). The fact that I can do 79 times 81 four different ways does not make 79 times 81 ambiguous!

      I know you are not a mathy guy, but I think even you really do know this.

      You're just trolling us.

      bud also wrote to me:
      >So, words are not inherently ambiguous and imprecise. They clearly are so, however, in the hands of people like you, whose thinking processes are befuddled by a pernicious belief in mathematicism.

      Gee, except I have actually used my knowledge of math to design and build complicated physical objects that actually worked: resulting in patents, a technical Emnmy for our team from the Academy of Television Arts and Sciences, the determination of electric fields in a drift chamber at SLAC, consumer products that you may even have used yourself (if you are not just a middle-school student, as I suspect), etc.

      And your own experience using math in actual physical STEM applications consists of ...........?

      Please fill in the blank for us, bud. You are very good at denigrating others who have real concrete achievements, bud, and very good at saying nothing about yourself. Indulge us, bud. Fill n the blank.

      Or do your achievements consist simply of manipulating words... and words... and words. And no math.

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    21. Luis wrote:
      > it takes time in terms of physical fields to go from one point to another; the nature of space and fields seems to be the same; this means that the measurements that some people make from Jupiter, Saturn, Tuesday and Uranus on the distance between the Earth and the Moon are relative...

      Ummm... no, not really. In terms of special relativity, which is what you seem to be trying to talk about, no, you really do not need for everything to be fields.

      Similarly, Einstein does not assume that, in your words:
      >everything is made of fields

      Both the special and general theories of relativity are very exact, quantitative theories. You cannot actually understand the theories without dealing with that. Relativity is all about quantitative measurements: you just cannot escape that.

      An extremely readable intro to special relativity, that requires only a bit of high-school algebra, is Hermann Bondi's little classic Relativity and Common Sense.

      If you find even Bondi too mathy, well, then I am afraid you are in the position of a deaf person who wants to learn to appreciate music: alas, it will not happen.

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    22. Jean Tate,

      Re: ...what are the experiments and/or observations (empirical by definition) that establish the "fact" that the "speed of light in the cosmos is not a constant"?

      Previously cited in this thread:

      https://en.wikipedia.org/wiki/Shapiro_time_delay

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    23. bud rap,

      You are very confused about what this experiment shows. Why not ask Google for some information before wasting our time.

      Delete
    24. bud rap,

      Thanks for explaining what experiments and/or observations you consider establish that the speed of light is not a constant (Shapiro time delay).

      If I combine this with "science was presented as a study of those things that can be observed and measured (broadly inclusive of mechanical extensions of our senses and experimentation)" (from a comment of yours in response to a different blog post), I come to the tentative conclusion that physics (astronomy, cosmology), for you, is like a cafeteria: you can pick and choose the items to suit your taste (or diet).

      Specifically, observations and measurements which assume that the speed of light is constant are perfectly acceptable, as are those which confirm the predicted Shapiro time delay.

      A problem with this is that the relevant science is a unified whole, no picking and choosing allowed.

      Perhaps an analogy might help.

      What was once a highly visible crackpot idea, "the Electric Universe", had fans (or acolytes, as it strongly resembled a new age religion) promoting both Arp's "redshifts do not tell distance" and Peratt's "spiral galaxy rotation curves are due to Birkeland currents" (I'm paraphrasing). And such fans were fond of citing both some of Arp's papers and a pair of Peratt's, to show that their beliefs were grounded in real science.

      The problem is (no surprises here) that Peratt explicitly assumed the Hubble redshift-distance relationship, while Arp just as explicitly rejected it. Thus a good example of a cafeteria approach (we can't really call it science).

      So here's a challenge for you, bud rap: show that accepting (almost all) astronomical observational results, as presented in relevant peer-reviewed journals, is consistent with a belief that the speed of light in the cosmos is not constant.

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    25. It is an old question whether rotation can be defined in the relativistic world of Einstein...

      It is indeed an old question, and it has an old answer: In special relativity the effects of acceleration present no difficulty at all, given the stipulation of global inertial coordinate systems, but of course that is incompatible with a fully covariant theory of gravity; in general relativity the effects of rotation are perfectly consistent with the fully covariant field equations that account for gravitation as well.

      Mach and Lorentz denied it.

      Not true. Mach’s contention (which Einstein championed for a long time) concerned the origin of inertia, and the suggestion that it might be found in the relations between material entities. However, like everyone else who has ever entertained that idea (Leibniz, Berkeley, etc.), Mach couldn’t make it work, and eventually Einstein recognized that Mach’s relationist idea lost it’s cogency in the context of general relativity, because the spacetime metric is a dynamical element of the theory (e.g., gravitational waves carry energy). Regarding Lorentz, your misunderstanding and misrepresentation of the 1917 correspondence has already been explained.

      Lorentz presented Einstein in 1917 his Gedanken experiment with a standing wave around the equator… Question is, in relation to what the nodes behave.

      This was debunked in the previous messages. There are two kinds of modern devices that exploit the Sagnac effect, one called ring lasers and the other called laser gyroscopes. The latter use standing waves in a circle, so it’s the same as what Einstein and Lorentz were talking about. Both kinds of devices exploit the fact that the inertial path length is different in the two directions. Again, Lorentz never denied that the effects of rotation (or any acceleration) are unintelligible under the relativistic interpretation (and neither an ether nor an absolute frame would “explain” inertia anyway).

      Einstein mentions the idea of Mach about the fixed stars background to have a reference for circular motion, which without such reference cannot be defined.

      Your conclusion is wrong. Inertial coordinates can be, and routinely are, established locally by their defining attribute: they are the local coordinates in terms of which the equations of physics (e.g., mechanics) take their simple homogeneous and isotropic form. You can read about this in any good book on the foundations of relativity.

      Einstein mentions here the Foucault pendulum, where Einstein regrets that it also shows nothing than a gravitomagnetic influence. - Here Einstein has no solution.

      Your claim was debunked previously. Again, Einstein noted the Lense-Thirring effect would also apply to Foucalt’s pendulum, but lamented that it would be too small to measure (at the time).

      Einstein’s bind of these guv to this background defines a fixed frame, and so Einstein gives up his most basic idea, the abstinence of just this fixed frame.

      You’re deeply confused. General relativity provides field equations, which are differential equations, but it doesn’t provide the boundary conditions. It imposes constraints on viable cosmologies, but doesn’t uniquely determine the cosmology. It’s well known that typical relativistic cosmologies have distinguished frames.

      The argument that this is a rotational motion and so SR not applicable can be circumvented by extending the diameter of the Sagnac circuit to infinity.

      That is just the well-known Selleri Fallacy. It’s trivial to show that the ratio of travel times around the loop differs from 1 by an amount proportional to the angle through which the ring rotates during the transit, and this remains true in the limit of increasing radius. Of course, we can also have the Sagnac effect on fiber optic conveyors of any shape, but this is all perfectly consistent with special relativity.

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    26. Amos:

      >>Einstein has described the relativistic reactions mathematically. He has based his system on postulates. Lorentz in contrast has deduced relativity from basic physical facts.<<

      >Lorentz and Einstein both described things mathematically, both based their descriptions on facts, and both postulated physical principles. It’s a myth that Lorentz deduced the Lorentz invariance of mechanics. True, he mistakenly believed (in 1904) that all mass was electromagnetic in origin, but that belief that never made any sense (as was clear to Einstein from the start). When Lorentz finally realized this (by the time he wrote his 1909), he recognized that he simply had to assume (postulate) that mechanical inertial and any other forces are Lorentz invariant… just as Einstein did. Of course, this is not an unfounded principle, it is forced upon us by the experimental facts. You can read about this in any good book on the foundations of relativity.<

      Lorentz has in fact *deduced* relativity. That happened in the following way: In 1888 Oliver Heaviside deduced from Maxwell’s theory that electric fields contract in motion. Lorentz used the assumption that the particles are bound in matter by electrical forces. What else could one assume? If now electric fields contract in motion, then all matter has to contract in motion. This at first explained the result of the MM experiment. Later there was the necessity to explain dilation. Lorentz solved it by assuming the internal oscillation with c in particles (which later turned out to be true). – All this did not use special principles but physics, known or plausible at that moment.

      Einstein in contrast postulated the constancy of c in any frame, so also in case of a transformation. So, he had to solve the equation
      c + v = c for any v /= 0. This is not possible within Euclidean geometry, so he had to find a new one. Einstein was successful to find a geometry which at the end was Minkowski metrics. – This was an exclusively mathematical process, no physics is in it.


      >>[Lorentz’s] way yields further physical insights which are not available from Einstein.<<

      >To the contrary, the subsequent history of physics (e.g., general relativity, the Dirac equation, etc.) has shown the trememdous heuristic value of the relativistic approach, whereas it was already clear by the end of the 19th century that the material ether concept had run out of heuristic value, and indeed had become a hindrence.<

      This subsequent history of physics is fully covered by Lorentzian relativity, and particularly general relativity developed on the basis of the Lorentzian approach is tremendously simpler than the Einsteinian one with similar results (you may find it in the internet). Ether in the old sense is not part of Lorentzian relativity. Lorentz only demands – as well as Mach – that there is a fixed frame, because without a fixed frame rotation cannot be defined. A problem which was never solved by Einstein as explained at another place.

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    27. Amos (2):

      >>The internal oscillation with c going on in all elementary particles, which Lorentz used to explain dilation, was a new information about the structure of elementary particle, which is meanwhile an accepted element of particle physics. Einstein’s relativity quite naturally does not yield such insights.<<

      >To the contrary, all the labor of the Maxwellians and Lorentzians to infer the structure of the electron turned out to be misguided and fruitless, whereas the Dirac equation (which led to the modern understanding of elementary particles) was solidly based on reconciling the quantum equation of particles with special relativity. This is perhaps the prime example of the heuristic value of special relativity.<

      The topic here was only the internal oscillation with c in all particles. This conforms to the particle-wave concept of de Broglie. And it was confirmed by Dirac for the electron using quantum mechanics. In addition, the senior of particle physics, David Hestenes said in 1999, that the particle properties spin and magnetic moment are caused by this oscillation. - Lorentz has stated this long time before all others.

      >>And we have the well-known open problems in present physics as are Dark Matter and Dark Energy, which have a solution with Lorentz, not with Einstein.<<

      >You’re alluding to a “fact” not in evidence.<

      For Dark Energy it is quite simple. In the Lorentzian relativity it is allowed and plausible that c changes with time, i.e. it decreases. If this altered c is used to determine the speed of Ia supernovae by Doppler, then the old ones turn out to have a higher speed than assumed by Riess and Perlmutter and so there is no acceleration.

      >>...if clocks are synchronized in this way, the subsequent measurement of c must always yield the same result... What Einstein does here, is a standard case of circular reasoning.<<

      >That’s another myth. Inertial coordinate systems (i.e., “systems in which the equations of Newtonian mechanics hold good” in the low speed limit) are defined based purely on the isotropy of mechanical inertia. The fact that the speed of light (or any massless energy) is isotropic and equal to c in terms of these same systems of coordinates is not circular. It implies that any energy E has inertia corresponding to E/c^2, from which it follows that inertial coordinate systems are related by Lorentz transformations. Again, you can read about this in any good book on the foundations of relativity.<

      The case is much simpler. The synchronization as given by Einstein and the subsequent measurement of c are identical processes. So if Einstein assumes for the synch process an equal c in all directions, then the measurement result must reflect this. And Einstein was aware of this as he (cautiously) admitted in his paper of 1905.


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    28. antooneo wrote:
      >In this case rotational motion can indeed be defined. But Einstein’s bind of these guv to this background defines a fixed frame, and so Einstein gives up his most basic idea, the abstinence of just this fixed frame. - And up to today there is no solution for this conflict.

      The solution is known and has been known for a very long time: General Relativity does not implement Mach's principle. This was a disappointment to Einstein, but c'est la vie!

      antooneo also wrote:
      >But this harmless result only applies if the Sagnac process is viewed by an observer at rest. For a co-moving observer there is a clear conflict, because in his system the speed of light has a different value for the direction with or opposite to the rotation.

      No, not at all: one can measure the speed of light with local measuring devices (rulers and clocks) and you will get the usual answer: this is, after all, what we actually do when we measure the speed of light here on earth -- no problem at all!

      The problem comes only when you try to use different inertial frames of reference spaced around the equator. But you cannot do that in special relativity: you have to use one inertial frame of reference (or -- very carefully -- do the appropriate Lorentz transformations if you insist on changing frames of reference).

      A simpler way of putting it: the "co-moving" observer is in a non-inertial frame of reference, which is forbidden in special relativity.

      What I find bizarre about all this is that the Sagnac effect would have been considered an easy homework problem where I did my undergrad degree (Caltech -- you should have seen our hard homework problems). That this has convinced so many crackpots that there is something wrong with relativity because they cannot do a frosh homework problem is a marvel to behold.

      antooneo also wrote:
      >The argument that this is a rotational motion and so SR not applicable can be circumvented by extending the diameter of the Sagnac circuit to infinity. In that case there is a continuous transition to a linear motion, but the difference of the speed in both directions will not diminish during the transition.

      Well... you cannot literally take the limit R goes to infinity because a circle is not topologically equivalent to a straight line. The limit is meaningless.

      But, you can get the desired effect by compactifying one spatial dimension so that you are doing the analysis on a (very large) cylinder, so that the problem is mathematically meaningful. And spacetime can then be flat.

      And you then see no paradox: your compactification has now made it impossible to get an inertial set of coordinates for someone moving along with the line that used to be the equator: in the compactified universe, relativity of simultaneity messes up building that coordinate system (there are different ways to compactify, but only one frame of reference will loop back unto itself nicely however you choose to compactify).

      All great fun to play with and no paradoxes, though illustrating the fun that occurs if you change the topology of spacetime. But of course people who lack the ability to solve frosh homework problems can never understand any of it.

      At all.

      (As Wikipedia notes, "The Sagnac effect has stimulated a century long debate on its meaning and interpretation, much of this debate being surprising since the effect is perfectly well understood in the context of special relativity." Indeed. How high is up? What color is truth? What happens to the doughnut hole when you eat the doughnut?)

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    29. bud rap wrote to me:
      >The speed of light in the cosmos is not a constant. That is an empirically based statement of fact. It is not disputable. The response you have to this, that if you could do something that you can't do, which is to hunker down in the vicinity of the sun or other similarly strong gravitational field, and under very contrived and constrained circumstances, measure, in the vicinity of your navel, you would find, "...the speed of light in vacuo as the well-known 299792458 meters per second."

      bud, we have many ways of measuring time beside the little plastic "Hello Kitty" clock that you keep on your nightstand that would indeed melt if you took it too close to the sun.

      Like spectral lines.

      Indeed, for over fifty years, the international standard for time uses a spectral line from the cesium atom.

      Your "Hello Kitty" clock is so passé!

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    30. Lorentz has in fact *deduced* relativity. That happened in the following way…

      No, it didn’t. As you can read in Lorentz’s 1904 and even more explicitly in 1909, he says “to the assumptions already made I add two new ones”, and he gives the explicit assumption (not deduction) of the relativity of mechanical inertia, which was not and can not be deduced from the laws of electromagnetism (once you understand that inertia is not primarily, let alone entirely, electromagnetic in origin). You are making the common mistake of focusing on length contraction and time dilation, whereas the actual essense of Lorentz invariance is relativistic dynamics, which does not follow from electro-magnetism. Everyone knows all about Heaviside ellipsoids and length contraction, the momentum of electromagnetic waves, etc., but that does not constitute special relativity.

      Later there was the necessity to explain dilation. Lorentz solved it by assuming the internal oscillation with c in particles (which later turned out to be true).

      This is simply untrue – Lorentz did not explain time dilation by assuming any such thing, nor did he anticipate the Dirac equation.

      Einstein in contrast postulated the constancy of c in any frame, so he had to solve the equation
      c + v = c for any v /= 0.


      That’s crazy. Special relativity does not assert that c+v=c, it asserts that if an object has speed u in terms of inertial coordinates S’ which are moving (in the same direction) with speed v in terms of inertial coordinates S, then the speed of the object in terms of S is (u+v)/(1+uv/c^2). Hence if an object is moving at speed c in S’ it is also moving at c in S.

      This is not possible within Euclidean geometry..

      That’s a weird statement. Euclidean geometry refers to space, and the space of special relativity is perfectly Euclidean. Time is not the same as space. When people talk about a pseudometric space-time manifold they are speaking about a convenient formalism that accurately represents the spatio-temporal relations. Those operational relations are not optional or ambiguous, they are empirical facts.

      The Lorentzian approach is tremendously simpler than the Einsteinian one with similar results (you may find it in the internet).

      Uh huh. But seriously, you’re the same guy who thinks relativity says c+v=c, so your ideas and beliefs on the subject are simply wrong.

      The topic here was only the internal oscillation with c in all particles… And it was confirmed by Dirac for the electron using quantum mechanics.

      The Dirac equation for the electron is Lorentz invariant, consistent with special relativity, so it makes no sense to try to use the Dirac equation to discredit special relativity. Also, you seem to be cryptically alluding to the “zitterbewegung” interpretation of the terms of the Dirac equation, but this in no way supports your weird claims, and to suggest that Lorentz anticipated the Dirac equation (and used it to explain time dilation) is simply false.

      For Dark Energy it is quite simple. In the Lorentzian relativity it is allowed and plausible that c changes with time, i.e. it decreases….

      First, the only viable Lorentzian relativity is just an interpretation of special relativity, so there is no operational difference. Second, whichever interpretation you like, re-phrasing the expansion of the cosmic scale factor as a coordinated change of the physical laws yielding indistinguishable operational facts is always possible. If you feel happier thinking that the scale factor of the cosmos is not changing but all the laws of physics are changing to make it appear that way, then go right ahead. This in no way supports your anti-relativity beliefs in any operational sense.

      The synchronization as given by Einstein and the subsequent measurement of c are identical processes.

      Again, inertial coordinate systems have an independent definition having nothing to do with light propagation, so your belief that it is circular reasoning is false.

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    31. Thanks to all comments about rotation; very sophisticated arguments have been presented. But I think that a quite simple consideration is sufficient to see the essential of it. I will answer here for the specific case of the Sagnac experiment.

      An actual use of the Sagnac idea is the fiber gyroscope. Two beams of light signal are sent in opposite directions through a fiber ring. They meet at the end of the circuit (in an assumed simple configuration) and undergo interference. This interference result is constant, if the ring is at rest, i.e. not rotating. If it rotates then the interference point moves to another position during the travel time of the light signals; the interference result will be different and indicate the rotation. – That is a very simple process which is in this view in no conflict with relativity; as I have mentioned in my former comment.

      But now this process in the view of a co-moving observer (who may be a navigator on a ship or in a plane): With respect to his platform, the signals need a different time to reach the same point, when moving clockwise or counterclockwise respectively. So the speed in relation to the platform is different for both directions.

      But the platform is in rotation, so the standard argument is that here special relativity is not applicable and so also its principle that the speed of light is always constant. But we can envision a continuous transition to a linear (straight) motion.

      I have formerly mentioned the theoretical possibility to extend the diameter of this fiber ring to infinity. But maybe that this is not imaginative enough. So, the other possibility: The reduction of the measurement distance to a differential step.

      In the view of the observer on the platform, the speed of the signals is c + v and c – v where v is the speed of the ring at its surface. Now the observer may measure this speed not at the end points of the ring but takes small sections of this ring and measures the speed there. This is logically possible (even though it may be technically difficult). By symmetry considerations the speed must be the same in all sections. And now he may install a straight leg along one section as parallel to it as possible and moving in the same direction. And he may send a similar light signal along this leg and measure its speed. - We will expect that he in this case measures the nominal c. And this is different from the c +/- v in the fiber. Is this a conflict?

      At the first glance there is formally no conflict as the one piece is curved and the other one is straight. But we can now reduce the length of both pieces, and then the geometrical and the physical difference of both disappears by the reduction, but the speed difference is constantly +/- v . - It is essential here that the difference +/- v does not decrease during this transition. (Such transition is a proceeding generally used in physics and mathematics.)

      This is now definitely a conflict. But how can this conflict be explained? - It is easily explained if we consider how the speed of light is measured on the straight leg according to Einstein. The measurement needs two clocks at both sides of the leg, and both have to be synchronized according to Einstein’s prescription. And this guarantees (as explained earlier) that the result in this case is always the nominal c irrespective of what nature does in reality. The Sagnac value is correct only.

      Summary: The speed of light is not constant; it only seems so if we follow Einstein’s synchronization.

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  31. Ja "The Unicorn Theory" more on this please! maybe a good name for abstract theories and notions...
    Anyway happy new decade Sabine; und genieBe ihrer Blog!

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  32. OTOH :)

    https://arxiv.org/abs/0806.0241

    -drl

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    1. "The obtained formulae reproduce the Pioneer Anomaly experimental data." - written in 2008. Ouch!

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    2. :) I actually posted a similar result as a comment on Google Groups back in 2007. It is fascinating that one can get both the "centeredness" of the universe (CMB asymmetry) and the Hubble law from conformal kinematics. The centeredness comes from the universal four-vector Am in the comment, which we assume to be time-like. Its rest frame is that of the center. In a sense, it points to the center.

      Link and follow-up. The derivation is refined further down.

      https://groups.google.com/d/msg/sci.physics.research/6TSzgPFTrdY/-d_c2Hatdq0J

      -drl

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    3. BTW I suspect this is related to Segal's "chronometric cosmology" somehow. I would appreciate any insight anyone might have about that. I have Segal's book for reference.

      (Mathematical Cosmology and Extragalactic Astronomy - I. E. Segal 1976, Academic Press)

      -drl

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    4. (PS by center, we don't of course mean a specific point that is literally the center - it means there is a global rest frame, and it is affine in nature, no origin, all points equivalent. The universal time-like 4-vector Am tells you "go in this direction at this speed, and you'll be in the global rest frame.")

      -drl

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  33. Hawking and Ellis conclude their classic treatise with these words: "The results we have obtained support the idea that the Universe began a finite time ago. However, the actual point of creation, the singularity, is outside the scope of presently known physics." (1973, The Large Scale Structure of Space-Time). Those words still ring true. In 1990, Kolb and Turner wrote: "loose ends are not inconsistencies within the hot Big Bang model itself; rather, they involve questions that the model (in the splendor of its success) allows one to ask, but, for which the model has yet to provide answers." (1990, page 261, The Early Universe). Those words still ring true. Now, read: "Big Bang Nucleosynthesis still marks the boundary between the established and the speculative in Big Bang Cosmology...although the Standard Model provides a precise description of physics up to the Fermi-scale, cosmology cannot be traced in detail before the Big Bang Nucleosynthesis era." (page 380, Review of Particle Physics). My point is this: even accounting for speculations on behalf of theorists, we are certainly no worse off than we would be otherwise. How else to proceed beyond those successful "standard" models than with mathematical investigation ?

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  34. There are many people who base their cosmovision on the fact that elementary particles form the entire universe and therefore they must determine it. In each degree of organization of the matter, the whole and the parts keep a close relationship; our conscience somehow modifies and subordinates the basic functions; otherwise, it would not be a new property; that is why quantum physics is far from explaining consciousness, it has many intermediate steps of new properties; the difference between a paramecium and the cell of a multicellular animal is due to the subordination to the animal as a whole and is modified to perform a specific function within the whole, but let's go to the physics itself; a cloud of gas and dust constitutively does not differ from a star, they are composed of the same; but the star as a whole subordinates all particles and is capable of modifying it to the point of creating heavier atomic nuclei, and even more so, deleting the asymmetry (lepton-barion) from the atom, and even more, deleting the quark asymmetry; that is, microscopic transformations need a macroscopic event. This also has another explanation; particles and fields do not have a definite time direction, they do not exist from past to future, they exist in all directions of time; but it is precisely the macroscopic objects that gives them a certain temporal address; Of course, you can measure temporal properties in the particle; but it does so from an organized time frame; I would go even further, even space may owe its organization to macroscopic objects, without them it can lose its isotropy and symmetry; I mean that you need a macro object that allows a unified field, and a beginning of space and time in a more or less organized way. A soup of particles with quantum properties alone will not solve the problem. My impression is that black holes were born directly from the big bang; and if so, we are still in "big bang"

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  35. "Up to a temperature of about a TeV, we understand the physics of the early universe and we can reliably tell what happened."
    Do we really know everything about neutrinos?

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  36. curious george asked:
    >Do we really know everything about neutrinos?

    I did my doctoral thesis on the lepton sector of the Standard Model, specifically the tau neutrino, so I can answer with at least a bit of authority, "No, we really do not know everything about neutrinos!"

    Of course, in the context of this discussion, the question would be "Do we known everything about neutrinos relevant to cosmology."

    Harder question: I think the answer is "We sorta think we do, but we might be wrong." If Jean Tate disagrees on this question, I defer to Jean.

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    1. Ah neutrinos! :)

      Ice Cube (the amazing detector buried in ice at the South Pole) has detected a modest number of rather high energy neutrinos. Where did they come from? Very likely AGNs (active galactic nuclei) but maybe some exotic supernova; an open question. More so: what, in some detail, is the physics of their production? With a lot more data, I expect models could be constrained.

      Cosmologically: analyses of the CMB data strongly suggest that there are only three kinds of neutrino (and anti-neutrino); that corresponds nicely to what we know in the lab (electron, muon, and tau).

      Corresponding to the CMB there is a CNB (cosmic neutrino background) from the time neutrinos rather than photons "streamed free". It would be wonderful if the CNB could be detected, and observed! It should tell us, pretty directly, what the early universe was like, when its density and energy were higher than regimes probed by the LHC. To even detect the CNB is a huge experimental challenge. But at least one group is making a serious attempt, PTolemy (link: https://pos.sissa.it/283/092/pdf). Let's hope they succeed!

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    2. Ah neutrinos, indeed. Look at pages 164-165 of my DOI: 10.13140/RG.2.2.10103.68007: "...as a rough calculation, we can say that in our day-to-day existence, one CvB neutrino flows through any one-barn cross sectional area approximately every 15 minutes." And this is the same as the mean lifetime of a free neutron. So, when we account for the weak Z-boson interactions between these CvB neutrinos and neutrons, this is not just a coincidence: When a free neutron "spontaneously" decays into a proton after 15 minutes on average, it has done so *precisely* because it just interacted with a CvB neutrino, resulting in a proton plus electron.
      So, Jean says "to even detect the CNB is a huge experimental challenge." But in fact, each and every time we see a neutron spontaneously decay into a proton, it is because it collided with a CvB neutrino. So the experiment you want is to post a "guard" next to a bunch of neutrons, and see if we can find these CvB neutrinos colliding with the neutrons every 15 minutes on average in advance of these neutrons' decaying.

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    3. There is something that I do not understand; It is said that the energy of CvB neutrinos is very low and if each of them can interact with a neutral with an incidence of 15 minutes; my question is; Why does it not disintegrate with the millions of other neutrinos with more energy that pass during those same 15 minutes? sorry for my ignorance

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    4. Interesting. Has this been published in relevant, peer-reviewed journal? Have you submitted it to one?

      What implications does this have for neutron stars? For neutron decay near an intense source of neutrinos (e.g. a nuclear reactor)?

      Yeah, I know it's written as CvB, but I much prefer CNB because "v" is a poor relative of the Greek letter nu.

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    5. Jay Yablon brought our attention to his unfortunately novel theory of neutron decay presented in this paper: his idea is in his Part IIC, Section 23 -- see especially his figure 16.

      What is unfortunate for Jay is that neutron decay has been extensively studied experimentally.

      Jay's "neutrino trigger hypothesis" claims that, in the initial state, a very low energy neutrino combines with a neutron to produce a final state consisting of an electron and a proton, and that this explains supposedly-spontaneous neutron decay.

      The total energy of the final electron and proton combined would therefore be just slightly higher than the energy stored in the initial neutron according to E=mc*2 (slightly higher because you need to add the very small energy of the initial neutrino). There is no significant wiggle room here: all the neutron energy (plus a little bit more) must go into the electron and the proton.

      The conventional analysis of spontaneous neutron decay is very different: you start with a neutron all by itself which spontaneously decays into an electron, a proton, and an anti-neutrino (see figure 1 of the second document).

      The anti-neutrino always takes away some of the energy, so that the electron and proton energy combined must be less than the initial energy of the neutron, and, indeed, there is a continuous spectrum of electron energy due to the fact that the anti-neutrino can take away a varying amount of energy.

      By the way, historically, this missing energy in a continuous spectrum is what caused physicists initially to realize that neutrinos must exist more than eighty years ago. This is not a new concept.

      I invite everyone to look at Figure 3 of the second paper on the energy distributions of the electron and proton, and indeed read the entire paper and form his or her own opinion on Jay's theory.

      Jay is, it seems, an attorney, so I will refrain from expressing my own opinion of his work. Let us just say that the experimental data tells us something -- a whole lot of something! -- about whether or not he knows what he is doing.

      And, given Jay's day job, I assume he will have a lengthy and wordy response (his paper is over 190 pages!): I mean why should we care about experimental data when we have words and words and words...

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    6. Dave, your analysis of the energies involved in the decomposition of the neutron is very clear, there is no doubt about that; the analysis of the energetic process is as important as the geometric-temporal; on the other hand, I have been analyzing Bell's theorem for some time and I find no contradiction that postulates "non-locality" in the way it does; I am not a theoretical physicist, maybe you can clarify me; I start with an analogy, I know that these are not good; suppose I want to know the sea level; but this one has waves, let's replace it with a sinusoidal wave; then I measure when it is at 90 degrees; give 1 and of course this measurement is incomplete; because a statistical measurement does not depend on a single measurement, collapse ???; but wait, I can make two measurements in the two parts of the opposite wave, in 90 and 180, the average measurement gives me the value 0, which is the actual height of the sea level; now, instead of measuring in 90 and 180, I measure in 45 and 180, and the fact of reducing the angle in half does not reduce the value to me in half, it is reduced in function of the trigonometric value of sinus; I don't know where the interpretation comes from that a classical system should give 0.5. I can even measure the ridge of one wave and the valley of another one a mile away and I get the same result as if I did it with its own valley; what is the mystery? Are they waves? I really don't see it; It only seems to me a mystery if the space were a total void, and the particle was not something that exists within a temporal interval and without any relation to the space. Can this analogy be confusing me? , it may not be equivalent to the quantum experiment ?, I think my classical experiment is the equivalent of the quantum, I just think, don't misunderstand me. Thank you

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    7. error, where it is written 180, must be 270, sorry

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    8. I must reply to Dave on three matters: 1) his scientific observations about the triggering of neutron decay as proposed in section 23 of my preprint DOI: 10.13140/RG.2.2.10103.68007; 2) his passing remarks about the first 22 sections of this preprint, and 3) his utterances about me personally and my vocation. (I will hit character limits, so if OK with Sabine, I may need a few posts for proper reply.)

      As to 1): Dave is absolutely correct that I made a huge error which requires me to *hereby retract* my Feynman diagram in Figure 16. And Dave, thank you for pointing this out! I had not before seen the specific energy distributions in Figure 3 of the “second paper” you linked, but was keenly aware of the neutrino having originally been proposed 90 years ago to enable known conservation laws – mainly energy/momentum and spin – to be respected during weak beta decays. I absolutely had the knowledge necessary to put two and two together and figure out that an antineutrino was used and *had to be used* to cart off the neutron minus proton rest energy difference which is more than twice as large as the electron rest energy, and that an incoming neutrino would not do that trick. But I made a mistake of the sort we humans occasionally make (and some more than occasional) when we find an idea to be so attractive, that we subconsciously fail to assemble and properly weigh evidence we may have in our possession which would contradict that idea. Mea culpa, I did that here. That is why we have one another to bounce things off of, that is why we have peer review despite its having the flaws of any undertaking which involves humans, and that is why we agree as a community to put experimental data ahead of what the *entire community* believes if that data demonstrates a contradiction.

      The idea I found so attractive which blinded me to the evidence in my possession which I was overlooking, was: the fact that based on the experimental data from my Figure 15 reproduced with attribution from Figure 1 of https://arxiv.org/pdf/1207.4952.pdf, there will be one CNB (respect to Jean) neutrino flux through a 1 barn = (10 fm)^2 cross section every 15 minutes or so; my muscle knowledge that this is *also* the mean lifetime of a free neutron; what is a fair approximation of (1 fm)^2 as cross section for a neutrino; my understanding that Z bosons might provide a mechanism to attract (see e.g. (23.13)) a neutrino – especially a slow CNB neutrino – into the neutron cross section only one linear order of magnitude smaller, because the strongest weak Z attraction a neutron ever experiences is from a neutrino; and my knowledge that neutrinos and antineutrinos were exactly the particles Pauli had first postulated to do the conservation accounting for weak beta decays and so were right on point to be used for the problem at hand. But in my rush of enthusiasm for what to me could not be mere coincidences, I did the energy accounting bass-ackwards. The question now is whether those “coincidences” might still be explained as more than coincidence, with the energy accounting’s behind moved, well, behind. And with less than 12 hours to have thought about this following Dave’s correct point which I again appreciate his having made, I do think this accounting can be fixed. First draft of “here is how”: (character limit, need to submit a part B) . . .

      Delete
    9. (part B because of character limit) . . . Instead of Figure 16, replace this with a new Feynman diagram inside the 15-minute box centered around the correct decay path n -> p W^- -> p e v-bar. And also, run a CNB neutrino line v parallel to the decay path, and include a few Z boson lines showing this v attracting with a) the n, b) the W^- after n->p, and c) the v-bar after the W^- -> e v-bar decay. And finally, d) annihilate the v-bar by colliding it with the v from the CNB and then spewing out all that energy. Then what happens physically is this: Based on their natural empirical fluxes, and with the aid of Z bosons to get “into the cup” once it is “on the green” (golf), a CNB neutrino gets close to a neutron (inside the 1 barn surface) every 15 minutes on average. The neutron is now feeling that extra Z pull (or z chain pulls, see page 174) from the nearby v. But the energies do not add up, as Dave points out, so the v cannot annihilate the n. So, just as a lightning bolt discharges electricity when there is a charge imbalance, this Z pull from the v instead forces the n to discharge a W^-. During its brief and slowly-moving life, the W^- and v will continue to have a very strong Z attraction so they will stay close and keep pace. Once the W^- decays, the v will have found its v-bar mate, but the v-bar will start out moving a lot faster because it now carries all the extra energy Dave correctly talked about. But neutrinos are as light-as-can-be without being massless, so the Z attraction between v and v-bar will easily cause one to accelerate and the other to deaccelerate until they are both able to annihilate.

      The key experimental question then becomes whether, following the correct decay path n -> p e v-bar, the v-bar very soon annihilates with the CNB v which precipitated the whole decay chain in the first place when it drew “drawing lightning” in the form of n -> p W^-. But do keep in mind, “very soon” could mean that both v and v-bar are round the world and back by the time they annihilate. And since these little devils can pass through the whole earth without anything happening, you can’t manipulate them into accelerator rings in the same way as you can other particles. Calling the folks at IceCube! Ideas?

      If you can poke holes in the last two paragraphs, please, be my guest. If nobody can take a fatal stab, then I will draft up a new Feynman diagram replacing Figure 16, and change everything else that was based on Figure 16 accordingly.
      If Sabine is OK with this, I will address points 2) and 3) above of my reply to Dave, separately, later.

      Delete
    10. Oops, typo in very recent submission:

      "...what is a fair approximation of (1 fm)^2 as cross section for a NEUTRON;" (not neutrino). You all would probably figure that out anyway.

      Delete
    11. Jay R. Yablon,

      First, I give you (partial) credit for admitting you were wrong. Of all the non-scientists here who have their own radically wrong theories, you are the first I know of who has admitted he was wrong.

      Why only "partial" credit?

      Well, for example, you wrote above:
      >Then what happens physically is this: Based on their natural empirical fluxes, and with the aid of Z bosons to get “into the cup” once it is “on the green” (golf), a CNB neutrino gets close to a neutron (inside the 1 barn surface) every 15 minutes on average. The neutron is now feeling that extra Z pull (or z chain pulls, see page 174) from the nearby v.

      That is not how the weak interaction works.

      It is really, really weak. Just getting within a fermi/femtometer of the d quark in the neutron is not enough.

      The ultimate reason for this is that the particles carrying the weak force (W+/- and Z0) are really heavy. This heaviness, in quantum mechanics, translates into being really short-range (conceptually, it causes the exponential die-off in space for the virtual particle to be very, very rapid). Being, as you put it "on the green" is not enough.

      Now, before you run off with this to make a new theory (!), let me add that this is just a rough conceptual description of what is happening: to do this right, you need to do quantum scattering theory correctly and so on: for example, when you have mastered everything in this paper (I mean you can redo the calculations yourself!) you might be ready for your new theory.

      But before you do that, you first need to fully master the paper by J. S. Nico that I pointed out to you above. If you do master the Nico paper, you will find out that we have no need for your new theory: we already understand what happens very well in spontaneous neutron decay.

      And this raises the broader question here: you have put a substantial amount of work into writing various papers on physics. But, in looking over these papers, I have yet to find anything new that seems to me as if it has any chance of being true.

      For example, in your April 25, 2018 paper on electron-photon interactions and the electron anomalous magnetic moment, you refer in the abstract to "renormalization and other ad hoc add-ons." That is very, very disturbing: renormalization is not an ad hoc band-aid added on to the theory to somehow make it fit experiment. Renormalization is mathematically required. If you sidestep it, you are wrong.

      And sure enough, looking through the paper, as soon as you depart from whatever textbooks you are relying on for standard material, you make errors. For example, you derive the Lorentz force law and the General Relativity law of motion using a variational principle. But then you state:

      >Therefore the Lorentz Force motion which has been thoroughly validated empirically over the course of decades can indeed be understood as geodesic motion just like the gravitational motion. This does not appear to have previously been reported in the literature, and so warrants attention at least from viewpoint of at least mathematical physics.

      What you are trying to do here is routine textbook material, known since early in the twentieth century.

      But you have not seen it reported in the literature because you are using the wrong terminology: "geodesic" means a path that is stationary in terms of the proper time, and that is not what you calculated. You are misusing the term "geodesic" and so cannot find anything in the literature that similarly misuses the term!

      It would be funny, except you have clearly put in a lot of work on this.

      Delete
    12. Jay R. Yablon,

      Sabine recently said that one of the biggest tasks of a theoretical physicist is to first learn and understand what other people have done. You and our other non-scientist friends here who are so eager to develop their own theories (and attack various well-established scientific theories) are not doing this at all.

      So, I have a sincere question for you and all of our other would-be physicists here: in all honesty, what would it take to get you guys to dump all of the bizarrely atrocious work you have done and resolve to actually learn and understand the standard textbooks and the standard literature before you start developing your own theories?

      I suppose there is a selection process here in which we just never see the people able and willing to do this. I, for example, would like to settle the “Continuum Hypothesis” and the “Axiom of Inaccessibility” once and for all (yes, I know the independence results vis a vis ZFC). And, hey, I’ve had a few ideas over the years (I once thought I could prove the Axiom of Inaccessibility: my delusion lasted a few days). Fortunately, I have had good enough judgment to not write up and try to publish any of my half-baked ideas in that area.

      In venues like this, I suppose we are seeing the people who lack that level of self-perception.

      Is there anything that can convince you guys that you are doing all this completely wrong, that what you are doing is guaranteed to be utter and complete nonsense?

      Or is it like some genetic diseases: if you were born with it, it is just incurable?

      Delete
    13. Luis,

      Re Bell's theorem: I have found from experience that I am not the best person to explain Bell's theorem to others (it seems obvious to me, but my explanations do not seem obvious to others!). Anyway, I will give you a few suggestions.

      First, I strongly suggest reading Dave Mermin's classic article, "Is the moon there when nobody looks? Reality and the quantum theory?"

      I also recommend John Bell's own essay, "Bertlmann's Socks and the Nature of Reality."

      Now, as to what is going on in my words:

      The idea is that you have two separate systems on which you can do measurements. On each system you have to choose to do only one measurement, but you get to choose that one measurement out of a variety of possible measurements. Each measurement gives a simple Yes/No answer (or 1/0, if you like).

      Now, the key assumptions about these measurements is that, although you can only choose one for each system, the system, in some sense, already "knows" what value it will produce for whatever measurement you happen to make. And it will give that answer regardless of what measurement you make on the other system.

      These two assumptions are stated in different ways by different people and are given different names by different people. The names I like for these assumptions are "counter-factual definiteness" and "Bell locality."

      Anyway, whatever you call these assumptions, Bell derived from them a simple inequality comparing the fraction of agreement or disagreement between the two systems when you do measurement A on the first system and measurement B on the second system, or measurement C on the first system and measurement D on the second system, or whatever.

      There are various ways to derive this inequality: when you master the derivation, it seems a bit trivial and utterly obvious. A bit like saying an animal is either a cat or a dog.

      Remember again: the whole point of Bell's theorem is to consider the fraction of agreement or disagreement between a measurement on the first system vs. the second system. It is comparing the answers between the two systems that is the whole point: how often does measurement A on the first system give the same answer as measurement B on the second, and similarly for other possible pairs of measurements on the two systems.

      You are not concerned with comparing different measurements made repeatedly on one single system. It is comparison between the two systems that is the point.

      The problem with understanding Bell's theorem is just getting this all straight in your head. It's not really that hard, not much harder than computing, say, Major League Baseball standings among the different teams.

      But you have to focus on the computation you are actually beings asked to carry out: the fraction of agreement or disagreement between the two systems for different possible measurements.

      If you patiently get this straight, you end up thinking, "Yeah, this inequality must be true, but it is trivial -- it has to hold true for any two systems that cannot communicate to each other what measurement is being made on the other system." By the way, it is perfectly fine if the two systems communicated in the past: even if they "conspired," so to say, to always give the same or contrasting answers, the inequality still holds.

      And then we spring the physics on you: quantum physics predicts a violation of the Bell inequality.

      And, worse still, experiment confirms quantum physics: this inequality, which obviously must be true is violated in the real world.

      So, how can that be? How can the impossible be true?

      Thus ends the prologue and now the play begins:
      Enter physicists stage left and stage right for the opening fight scene...

      Delete

    14. Thanks Dave for your response and your patience; you are right, it is a belief of mine turned into an obsession, to think that space has a dynamic structure and the fields take the form of that structure; I'm supposed to understand the math behind this; but this obsession has left me out of mathematical analysis, it also happens to me with all quantum physics; I think that if there is a dynamic that has structured the space in small intervals of time and space and in some way the particles are of a similar nature, and that is why they are linked to space; That is why I believe that a single measurement cannot describe the entire system, as I also believe that in some way the interaction of the particle with space plays a role in the measurement. The bad thing about this obsession is that it totally distances me from the real and proven mathematical analysis. Your two responses to my comments remind me when my teacher surprised me asleep, gave me a tap and told me - "pay attention to the class", hahaha. Thanks Dave, I will try to review the math again.

      Delete
    15. Paul Dirac: “Hence most physicists are very satisfied with the situation. They say: ‘Quantum electrodynamics is a good theory, and we do not have to worry about it anymore.’ I must say that I am very dissatisfied with the situation, because this so-called ‘good theory’ does involve neglecting infinities which appear in its equations, neglecting them in an arbitrary way. This is just not sensible mathematics. Sensible mathematics involves neglecting a quantity when it turns out to be small—not neglecting it just because it is infinitely great and you do not want it!

      Richard Feynman: “The shell game that we play…is technically called ‘renormalization.’ But no matter how clever the word, it is what I would call a dippy process! Having to resort to such hocus-pocus has prevented us from proving that the theory of quantum electrodynamics is mathematically self-consistent. It's surprising that the theory still hasn't been proved self-consistent one way or the other by now; I suspect that renormalization is not mathematically legitimate. What is certain is that we do not have a good mathematical way to describe the theory of quantum electrodynamics: such a bunch of words…is not good mathematics.

      PhysicistDave (the social media pseudonym for some anonymous guy may or may not have ever written a coherent work because he doesn’t tell us who he is): “For example, in your April 25, 2018 paper on electron-photon interactions and the electron anomalous magnetic moment, you refer in the abstract to ‘renormalization and other ad hoc add-ons.’ That is very, very disturbing: renormalization is not an ad hoc band-aid added on to the theory to somehow make it fit experiment. Renormalization is mathematically required. If you sidestep it, you are wrong.”

      Hmmm. Dirac and Feynman on the one hand. Some anonymous guy who specializes in ad hominem internet attacks on the other. Whom should I go with? Let’s get real here.

      The paper Dave references is at DOI: 10.13140/RG.2.2.30513.48480. Here is the basic issue: Dirac’s equation famously predicts a magnetic moment g-factor g/2=1. Experiments on the other hand show that g/2=1+(1/137.036)/2pi+…. This difference between theory and experiment is called the “anomaly.” The first-order term is courtesy of Julian Schwinger. A whole enterprise involving Feynman diagrams with high-order loops and renormalization has developed to fill this gap. Beyond third or fourth order terms, analytical analysis is impossible and you need computers because there are just too many diagrams. But it all works beautifully with uncanny precision. And because it is all we have right now, we use it while (some of us at least) hope something better comes along which is not so “dippy,” yet does not sacrifice a single decimal place of empirical accuracy.

      Next to Einstein, there is no 20th century physicist I admire more than Dirac. But the problem here stems from Dirac’s equation, and the fact that it predicts g/2=1, while experiments show this this is “on the green” but not “in the cup,” because of the anomaly. If Dirac’s equation itself were to predict “g/2=1+some small number” from the outset without the dippy stuff, and if we did not lose any precision, then that is exactly what Dirac and Feynman would have wanted to see.

      The preprint at the above DOI shows that the anomaly is rooted in a type of electromagnetic time dilation which is similar to what we have for relative motion in SR and gravitational wells in GR, and leads to a broad connection between time dilations and energy content which likely applies universally for *all* interactions. And, not a bit of precision need be sacrificed. Part IV develops this in detail. Part V proposes six (6) different experimental tests.

      To be clear, I am still using a form of renormalization, from “bare” to “dressed” quantities. But there are only *finite* quantities. See, e.g., reference [17] by Scharf.

      Delete
    16. I said the other day that I would reply to Dave later, regarding his ad hominem comments about me and my vocation. I did not want to have to reply because this sort of thing should have no place in a physics discussion. So, I waited a couple of days to see if the need to reply would become moot with perhaps some self-recognition by Dave of the lines he crosses. Unfortunately, it has not. So, this will be in two parts due to character limits, and I hope done thereafter with no talk about anything but physics.

      Dave: “First, I give you (partial) credit for admitting you were wrong. Of all the non-scientists here who have their own radically wrong theories, you are the first I know of who has admitted he was wrong.”

      First, who made this a classroom and appointed you to be the teacher and hand out grades to students? Or to proclaim me a non-scientist? Frankly, how dare you! Maybe the reason I am the first to do something you didn’t expect me to do is because you are trying to set me up as a straw man for all the people in the world who want to deny relativity and experimental evidence and maybe claim flat earth. Then you give me “credit” if I don’t behave like the straw man you tried to paint me as? No, I do not accept that!

      Dave: “Jay is, it seems, an attorney, so I will refrain from expressing my own opinion of his work. . . . And, given Jay's day job, I assume he will have a lengthy and wordy response (his paper is over 190 pages!): I mean why should we care about experimental data when we have words and words and words...”

      This is another demagogic gem: Everyone hates lawyers so let’s just call Jay out for being a lawyer and everybody will be dismissive of him forevermore. He deliberately left out that my 190 pages “of words and words and words” has 300 to 400 numbered equations and 16 figures in it! Damn, that Feynman was one heck of a lawyer. His Lectures on Physics had even more pages and more words!

      Sorry, Dave, that disingenuous attack is entirely out of bounds. But you are not the first who has tried to pull this stunt because I am not teaching and playing academic politics at a university somewhere. Or being home schooled by you because you don’t trust that anybody can learn anything the right way unless they learn it from you with some mix of partial credit and condescension. Theoretical physics has been largely stagnant since the 1980s, partly because of people behaving the way you do and others being professionally intimated by that. So, before you go after my nontraditional approach, let me tell you where I am actually coming from. I will do this briefly, because I really do not care to talk about myself, and most readers here really won’t care to hear it. Apologies in advance to those readers. And again, I hope to never have to return to this sort of reply.

      End Part I.

      Delete
    17. Part 2: If a professor at MIT who was the process of mentoring me onto the MIT faculty had not passed away suddenly (sadly stricken just a couple of hours after I had spent an hour meeting with him that morning), I very likely would have started my career in the 1980s on the MIT faculty in the physics or electrical engineering department. But as it turned out, due to a very strong parallel interest in political science and history (not to win trivia night, but because of how knowing the past always helps us better understand today and tomorrow), I took a detour, and went to law school. I quickly came to detest a profession that in many cases is just a giant pissing contest, as well as the many lawyers who will gladly piss for nothing other than getting paid well in return. So after an almost 10-year stint as a science policy advisor for the New York State legislature and then the Governor, on issues such as how to get the Superconducting Supercollider to locate in New York before nutjobs in our US Congress made sure the world’s premier leading physics facilities would be located in Europe, I started my own private business writing and securing patents for my clients who are all scientist and engineer inventors. These people are not looking to piss on anybody. They are creative and excited about what they do.

      So, in reality, I have written professionally about science and engineering for 35 years. But it has been for my employers, then my clients, rather than to other scientists or the public. So, despite your smug and offensive proclamation, I am no non-scientist! And my business success, fortunately, has given me the financial independence to study and write about physics in my own way on my own terms, with complete independence from any coercion to conform to secure tenure or a raise or whatnot. So that is what I now do. And you may have noticed, I am also quite proficient with mathematics.

      Also, I often see our self-proclaimed teacher Dave saying that that I (or someone else) have just never bothered to do our homework and read the textbook. Speaking as someone who has been through the Feynman Lectures, Weinberg's QTF, MTW’s Gravitation, knows H&M’s Quarks and Leptons by heart, pored over Ryder’s QFT, studied every square inch of Zee’s delightful QFT book, studied everything that JA Wheeler wrote on Geometrodynamics, and was taught SR and GR, personally, by Wheeler’s student H.C. Ohanian, to name a few, that is just plain !@*#@!. And I regularly study the PDG reviews. So, your lecturing me about slacking off and not studying this or that textbook, is just plain insulting. Maybe I just didn’t happen to read the textbook you think I should have read and say something they way your favorite text would have said it. But do keep in mind, I am not looking to teach the standard model of physics. I am trying the help end the stasis in physics, while at the same time urging an elevated tone for physics discussions which often sound no better than what we see from politicians running for office who have to win whether right or wrong.

      That said, Dave, you are knowledgeable guy. And because I am working independently, the interaction and feedback I get from you and others through exchanges in various physics chat groups such as Sabine’s, is very helpful to me. And I hope my thoughts here and there can be helpful to them. I just would ask you please get off of your high horse and realize that we are all pursuing a common goal of better understanding the physical world we each inhabit for a blessed handful of decades. And don’t be so surprised when you see that I am open-minded and will change my views if I see conflicting evidence. Because that is what a scientist must do, by definition. Peace, friendship, and let’s only talk about physics from here!

      Delete
    18. @PD,

      I think the problem originates with scientists, who pass off a lot of published bullshit of their own that isn't worth a damn. They just have the credentials to make it stick. Such behavior has been "in the air" for a long time (at least since the 1980s). And then there are extreme efforts to patch up ideas that obviously are not working. It's a sort of intellectual anarchy. And it has a corollary - sometimes really interesting ideas that are perfectly sound and worth thinking about, and perfectly in line with what is known and do not make outrageous claims or ignore known answers, just get lost in all the noise. Also - it often happens, even among the in-crowd, that really far-reaching conceptual mistakes are made and propagate. So the amateurs do not have a monopoly on doing the same wrong thing again and again and ignoring correct arguments. I see a lot of that even among experts.

      -drl

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    19. Jay R. Yablon wrote to me:
      >PhysicistDave (the social media pseudonym for some anonymous guy may or may not have ever written a coherent work because he doesn’t tell us who he is):

      You have not been around here a lot: I have given an enormous amount of information about myself, far more than almost any other poster here except, of course, Sabine, including my name: David Miller. I have gone into detail about my thesis work, about patents I am co-inventor on, about professors from whom I took various courses, even the fact that I have performed on stage with the actor John Goodman, who happened to attend my high school (John was two years ahead of me).

      Most people here have been anonymous: I have not been.

      I use "PhysicistDave" as a screen name mainly because that was the only account I could get to work on Sabine's blog initially, but also because there are more "David Millers" in the world than "PhysicistDaves."

      Jay also wrote:
      > So after an almost 10-year stint as a science policy advisor for the New York State legislature and then the Governor, on issues such as how to get the Superconducting Supercollider to locate in New York before nutjobs in our US Congress made sure the world’s premier leading physics facilities would be located in Europe...

      So, you were a lobbyist: that is not a scientist. I am glad, though, that you failed in your efforts to rip off taxpayers for the benefit of New York state.

      Jay also wrote:
      >So, in reality, I have written professionally about science and engineering for 35 years. But it has been for my employers, then my clients, rather than to other scientists or the public. So, despite your smug and offensive proclamation, I am no non-scientist!

      I pointed out a slew of utterly and truly bizarre errors connected to just one of your papers! You may have skimmed through those books, but, yes, you are most assuredly a "non-scientist"!

      Jay also wrote:
      >And I hope my thoughts here and there can be helpful to them.

      Not a chance, Jay: you are just making stuff up, as I proved in detail just in connection with one of your papers.

      Jay also wrote:
      > And don’t be so surprised when you see that I am open-minded and will change my views if I see conflicting evidence.

      No. If you had any understanding at all of all those books you skimmed, you would cheerfully admit that you really messed up on how your work refers to "geodesic" motion. And, then there is your ongoing failure to grasp how weak the weak interaction is and that it is not enough to get "on the green." And your utterly ignorant remarks on renormalization.

      No, Jay, there is a certain personality type that no matter how many times they are proven to be utterly ignorant and incompetent in some field of endeavor, it just makes no difference to them at all. They are completely unfazed.

      I just do not get people like you, though I have noticed they are very, very prevalent in your profession.

      Delete
    20. Luis wrote to me:
      >That is why I believe that a single measurement cannot describe the entire system, as I also believe that in some way the interaction of the particle with space plays a role in the measurement.

      Well, Luis, the nice thing about Bell's theorem is that it takes no stand on the structure of space, etc. The assumptions are very simple, as I outlined them.

      Luis also wrote:
      >Your two responses to my comments remind me when my teacher surprised me asleep, gave me a tap and told me - "pay attention to the class", hahaha. Thanks Dave, I will try to review the math again.

      Well, the nice thing about Bell's theorem and Bondi's book on relativity is that they can both be understood with a minimum of high-school algebra: I actually read the Bondi book when I was in grade school, before I had had any algebra at all. I actually taught myself a fair amount of algebra just trying to understand Bondi (made it easy to be the school district's star in Algebra I).

      What both do require is a willingness to think systematically and carefully: i.e., you cannot, as our friend Jay Yablon seems to do, just think to yourself, "Hey, that reminds me of this, and I wonder if this is connected to that" and so on.

      To put it in simple terms, you need to approach both Bondi and Bell's theorem as if you were doing your taxes (by hand -- no TurboTax!) and have to get it right.

      It's that self-discipline, the determination to refrain from just winging it, that most people lack. Most people want to feel good about their thoughts, not take a ruthless approach to eliminating thoughts that are mistaken.

      Of course, like most people, I do not like doing my taxes! And I do like doing physics, but simply because I look forward to the reward of understanding something about Nature that I did not understand before.

      But most human beings do not find the reward worth the tedium.

      Dave

      Delete
    21. Dave, it's me again, I've checked and reviewed the equations of relativity and I just saw the process quantitatively, but wow; the qualitative part is not removed from my head; I seem to be very stubborn; I explain myself, I go back to the distance between the Earth and the Moon, in the time that the light travels it, it makes a certain amount of wavelengths; Then, someone measures from a moving orbit on Mars and gets a time and length of the distance between the two points different from the one on Earth. My question is ; if there is no correspondence between the quantitative and the qualitative; will they obtain different amounts of wavelengths ?, or if there is correspondence between them, the frequency and wavelength change; but the amount of wavelengths will be the same ?; I include the variations produced by the gravitational field. Or everything I've said is absurd and distorted all reality? Oh, I also followed his advice in Bell's experiment, and wow! I see that yes, there is a contradiction between classical and quantum prediction; I also saw that there are a lot of physicists trying to find explanation; my example with the waves of the sea was, try to show a type of non-locality, I measure the crest of a wave with the valley of any other regardless of distance and the result is always the same; within the EPR experiment, it would be that the hidden variables are before the particles are separated, and throughout the path to the detector, and in the action of the detector on the particles; but well, I don't fantasize anymore; it seems that my illness has no cure

      Delete
  37. A lot of scientific progress was influenced by contradictions. But not every contradiction may be fruitful, unfortunately.
    Present theories, specially at microscopic level, are time reverse symmetrical ( but in fact full theory of course is CPT symmetric, which may seem remarkable). And there's a problem for cosmology, because it should have begging. So probably such exotic constructions like loss of scales in Penrose cyclic cosmology, or even more amazing inflation field, are traces of this discrepancy ( it probably could not be named contradiction, but for me, something do not fit here) between time rebersality of equations and "existencial beginning". In other words this theories are trying to fulfill time reversal symmetry and has to transfer irreversibility into something different: fields, dualities, strange and one time happen events.
    Probably this is just worthless thought...but something deeply wrong is with our understanding of time.

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  38. Every one here is nuts, and angry!

    Like a train wreck, however, it is hard to look away! But, I must.

    Everyone should read my Monograph. :)

    Happy new year and good luck to all.

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  39. I guess its to be expected that a discussion of how the Universe began would wander into religion. Personally, I wander back and forth myself between religion does more harm than good and vice versa. I know some very highly educated fundamental Christians who are far from morons. I also know some fundamental Christians who definitely are morons.

    Here's the problem. Religion had in the past two fundamental jobs. One, to explain the outer physical world. Natural catastrophes are the judgment of the Gods etc. Two, to guide the inner spiritual and moral world. Science has taken over the job of explaining the physical world, which is probably why some people accuse science of being just another religion.

    Informing the inner spiritual and moral world is still mostly the job of religion. Sins against the moral order are committed when religion fails at that task. But scientists are just as fallible in their own way as are religious people in their own way, so maybe a little less judgment all around would be a good idea.

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    1. Steve Bullfox 3:21 PM, December 31, 2019

      You can't base a moral order for modern societies with current knowledge on the norms of a primitive society with relatively little knowledge. Some people seem concerned about not being able to decide morals without "religion". Well, where do they think "religious" morals originated from - literally announced by a talking, burning bush or from evolved human nature, society and knowledge?

      E.g. Should people be ostracised or persecuted for being gay?
      No, because we now know people having gay sex won't cause a bad harvest.
      Your highly educated fundie acquaintances: Yes, because the Keepers of Bronze Age norms and commonsense tell them so.

      "But scientists are just as fallible in their own way as are religious people in their own way"
      Making a law to punish adulterers and gays by stoning to death, as in Brunei's Islamic code, isn't "fallible", though, is it? It's grade A psycho. This is what you can do if you allow ideologies with dogma that can't be questioned - kill whomever you like in any manner you like for no reason.

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  40. Sabine, I bought your book a week ago and finished reading it, it's very good; I laughed a lot with Weinberg talking like a book, almost ready to be printed, hahaha. I can not advise you in theoretical physics or mathematics, my rustic version of physics does not go beyond A = B, that equality fluctuates but they try, (I do not believe in any photofix description, everything exists within a time interval); Besides, your conversation with George Ellis is so great. Thank you very much for your book, it is magnificent

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  41. I must say this particular comment section is one of the best and most thaught provoking i have read. it will take me many reads to understand and to make sense for me.. thank you all

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  42. Jay R. Yablon,

    It would seem that you have not gotten any of your documents ("papers" for short) published in relevant peer-reviewed journals (if so, please point me to one/some).

    May I ask why (not)?

    Did you, perhaps, not submit any papers to any such journals? Or you did, but none were accepted for publication?

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    1. Jean: “It would seem that you have not gotten any of your documents ("papers" for short) published in relevant peer-reviewed journals (if so, please point me to one/some). May I ask why (not)?”

      Dear Jean:

      In 2012-2013 I had the following four papers published following peer review:

      1. https://jayryablon.files.wordpress.com/2013/03/hadronic-journal-volume-35-number-4-399-467-20121.pdf

      2. https://www.scirp.org/pdf/JMP_2013043014242019.pdf

      3. https://www.scirp.org/pdf/JMP_2013043014285020.pdf

      4. https://www.scirp.org/pdf/JMP_2013043014410549.pdf

      My primary research interest is in trying to understand why we observe the particular spectrum of rest energies that we do in fact observe in the natural world. That includes proton, neutron, and other baryon masses, the light nuclides (says, those with Z=1 to 10 in the periodic table), the twelve elementary fermion masses, and anything else regarding observed rest energy spectra.

      The most significant paper I have prepared since in terms of its connection to rest energies is the DKK paper at DOI 10.13140/RG.2.2.10103.68007, pieces of which I have been discussing here with Lawrence and Dave. I have not submitted this paper or any part of it for review and publication, to date.

      And since you asked why not, this is because in February 2019 I was working to get that paper into final form to submit for journal publication, when I was asked to become involved pulling together a workshop / symposium centered around the completeness of quantum mechanics, EPR Bell and the like. As you likely know, this involves some very sharply contested questions. Although this is not my primary area of interest per above, I agreed to do so, particularly because two good friends are at the center of these contests and one of those friends had been subjected to harsh professional treatment because of his holding dissenting views, of the sort that makes me thankful I am independent. I have spent virtually all of my free physics time since then occupied with this project.

      But the last several days here on Sabine’s blog have convinced me that it is time to move some of my attention back to where I left off almost a year ago, and get the DKK paper being discussed here into shape to submit for review and publication. I actually think now, that I need to break this up into a number of separate, tightly-focused papers. The first will be sections 1 through 5 which I have been discussing with Lawrence, exclusively focused on the question of establishing 5D covariance for the Klauza-Klein metric tensor. I believe this can be done in relatively short order.

      Thanks, Jay

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  43. Because I have been drawn into several other discussions under Sabine’s post “How did the universe begin?,” I would kind of like to talk about that too. These are my own personal views. I have not written any detailed papers about this, and you can care or not what I think. Your choice.

    Sabine hits the nail on the head when she says that “The simplest way to speculate about the early universe is just to extrapolate the known theories back to even higher temperatures, assuming that the theories do not change. What happens then is that you eventually reach energy densities so high that the quantum fluctuations of space and time become relevant. To calculate what happens then, we would need a theory of quantum gravity, which we do not have. So, in brief, the scientific answer is that we have no idea how the universe began.” All I would add, is “…or *whether* the universe even had a ‘beginning.’”

    I have no disagreement that the universe expands, and in another epoch could contract. But ideas such as a “Big Bang” stem from the Friedmann models of GR which are cycloids, because for every cycle, the radius of the universe hits zero and becomes singular, in a state that would have an infinite density of energy if we think about it classically. But among other things, quantum mechanics – particularly because of the exclusion principle for fermions – is a theory of pushback. Electrons really do not spiral into the nucleus, for example. So, because the GR models we use in cosmology do not incorporate quantum pushback a priori, and because we do not have a theory of quantum gravity, we get these singularities of infinite density instead. No doubt a sign of what we just do not know.

    Every year we witness a beautiful ebb and flow of the seasons. We just passed another solstice, and now the sun heads back to the northern hemisphere as we look toward spring. But we know that in June we will see a pinnacle, and just as our summer arrives, the sun will again decline. And while the approach of December might have made the ancients fear that the sun will set one night and be gone forever, we know that is not true. It always comes back. The cycles of nature.

    So my personal belief – and it is only a belief – is that once we do have a real theory of quantum gravity, we will find that we live in a universe of never-ending cosmological seasons: Winter, spring, summer, fall, and then again a new cycle, which each cycle on the order of tens of billions of years. Accelerating redshift. Deaccelerating redshift. Accelerating blueshift. Deaccelerating blueshift. A cosmological rainbow. And a “you are here” pointer to our present epoch. Yes, there are also entropic principles to account for. Sure, I’d love to see the theory and the math that proves it. But it would be in accord with the cycles of nature that we see everywhere else in our world.

    But alas, for now, all I can have here is a belief, plus the confidence that science has had a steady history of successes narrowing the scope of what belief is needed for, and expanding the scope of what we can assert as science with empirical and theoretical support. That is where I place my faith.

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  44. “In words that’s ten million billion Kelvin which sounds awkward and is the reason no one quotes such temperatures in Kelvin.”
    Sure, that's why we use the electron volt. The temperature has the much less awkward value of one thousand billion electon volts now.

    What I mean to say, Sabine: We could as easily say 10000 TK, or 10 PK. The reason we don't is not that the numbers are huge, but because we use interchangeable units for everything, and we have settled to use those for energy.

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  45. Jay R. Yablon wrote:
    >But among other things, quantum mechanics – particularly because of the exclusion principle for fermions – is a theory of pushback. Electrons really do not spiral into the nucleus, for example. So, because the GR models we use in cosmology do not incorporate quantum pushback a priori, and because we do not have a theory of quantum gravity, we get these singularities of infinite density instead.

    Jay, it is completely routine in astrophysics (in the structure of white dwarfs, for example) to take into account the pressure ("pushback" in your words) due to the exclision principle. That is what stabilizes white (eventually "black") dwarfs.

    But it is straightforward to show that above a certain mass that will not suffice. This is basically the Chandrasekhar limit (or Tolman–Oppenheimer–Volkoff limit for neutron stars).

    All this goes back to the 1930s.

    I or others can try to give you references in standard textbooks for this, if you wish, but if you have studied any astrophysics at all, you should have seen this.

    Also, relevant to all this, back in August, Pascal pointed out to me:
    >When a star undergoes gravitational collapse, it is known (from the Tolmann-Oppenheimer-Volkov equation) that the pressure at its center becomes infinite *before* it reaches the Schwarzchild radius.

    >You can find this in chapter 14 (on gravitational collapse) in the book by Adler, Schiffer and Bazin ("Introduction to GR" [second edition], equation 14.53 p.473).

    I have looked up Pascal's reference and carefully redone the analysis myself (all the way back from first principles). The reference he cites is indeed correct.

    The bottom line is that no one knows how to avoid the singularity: the exclusion principle will not do it.

    Most of us physicists suspect that quantum gravitational effects will kick in and prevent a literal singularity from forming, but no one can work out the details since we lack a quantum theory of gravity.

    Dave

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