Friday, December 06, 2019

Is the Anthropic Principle scientific?

Today I want to explain why the anthropic principle is a good, scientific principle. I want to talk about this, because the anthropic principle seems to be surrounded by a lot of misunderstanding, especially for what its relation to the multiverse is concerned.


Let me start with clarifying what we are talking about. I often hear people refer to the anthropic principle to say that a certain property of our universe is how it is because otherwise we would not be here to talk about it. That’s roughly correct, but there are two ways of interpreting this statement, which gives you a strong version of the anthropic principle, and a weak version.

The strong version has it that our existence causes the universe to be how it is. This is not necessarily an unscientific idea, but so-far no one has actually found a way to make it scientifically useful. You could for example imagine that if you managed to define well enough what a “human being” is, then you could show that the universe must contain certain forces with certain properties and thereby explain why the laws of nature are how they are.

However, I sincerely doubt that we will ever have a useful theory based on the strong anthropic principle. The reason is that for such a theory to be scientific, it would need to be a better explanation for our observations than the theories we presently have, which just assume some fundamental forces and particles, and build up everything else from that. I find it hard to see how a theory that starts from something as complicated as a human being could possibly ever be more explanatory than these simple, reductionist theories we currently use in the foundations of physics.

Let us then come to the weak version of the anthropic principle. It says that the universe must have certain properties because otherwise our own existence would not be possible. Please note the difference to the strong version. In the weak version of the anthropic principle, human existence is neither necessary nor unavoidable. It is simply an observed fact that humans exist in this universe. And this observed fact leads to constraints on the laws of nature.

These constraints can be surprisingly insightful. The best-known historical example for the use of the weak anthropic principle is Fred Hoyle’s prediction that a certain isotope of the chemical element carbon must have a resonance because, without that, life as we know it would not be possible. That prediction was correct. As you can see, there is nothing unscientific going on here. An observation gives rise to a hypothesis which makes a prediction that is confirmed by another observation.

Another example that you often find quoted is that you can use the fact of our own existence to tell that the cosmological constant has to be within certain bounds. If the cosmological constant was large and negative, the universe would have collapsed long ago. If the cosmological constant was large and positive, the universe would expand too fast for stars to form. Again, there is nothing mysterious going on here.

You could use a similar argument to deduce that the air in my studio contains oxygen. Because if it didn’t I wouldn’t be talking. Now, that this room contains oxygen is not an insight you can publish in a scientific journal because it’s pretty useless. But as the example with Fred Hoyle’s carbon resonance illustrates, anthropic arguments can be useful.

To be fair, I should add that to the extent that anthropic arguments are being used in physics, they do not usually draw on the existence of human life specifically. They more generally use the existence of certain physical preconditions that are believed to be necessary for life, such as a sufficiently complex chemistry or sufficiently large structures.

So, the anthropic principle is neither unscientific, nor is it in general useless. But then why is the anthropic principle so controversial? It is controversial because it is often brought up by physicists who believe that we live in a multiverse, in which our universe is only one of infinitely many. In each of these universes, the laws of nature can be slightly different. Some may allow for life to exist, some may not.

(If you want to know more about the different versions of the multiverse, please watch my earlier video.)

If you believe in the multiverse, then the anthropic principle can be reformulated to say that the probability we find ourselves in a universe that is not hospitable to life is zero. In the multiverse, the anthropic principle then becomes a statement about the probability distribution over an ensemble of universes. And for multiverse people, that’s an important quantity to calculate. So the anthropic principle smells controversial because of this close connection to the multiverse.

However, the anthropic principle is correct regardless of whether or not you believe in a multiverse. In fact, the anthropic principle is a rather unsurprising and pretty obvious constraint on the properties that the laws of nature must have. The laws of nature must be so that they allow our existence. That’s what the anthropic principle says, no more and no less.

173 comments:

  1. "The best-known historical example for the use of the weak anthropic principle is Fred Hoyle’s prediction that a certain isotope of the chemical element carbon must have a resonance because, without that, life as we know it would not be possible. That prediction was correct."

    Yes, this is probably the most famous example. However, it is often used as an example of something which people think is anthropic reason but actually isn't. (As my late history teacher used to say, just an observation, not a judgement.)

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    1. Hoyle's argument didn't just involve people - the same would apply to worms and paramecia. So it's not anthropic as such. The anthropic principle always seems to assume sentience. Maybe it should be generalized to the zootropic principle.

      -drl

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  2. "So the anthropic principle smells controversial because of this close connection to the multiverse."

    That's probably true today, though there were people who didn't like it even before the idea of the Multiverse was common.

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  3. I would say that the strong version is essentially useless and very probably wrong, while the weak version is trivial. That is, it is trivial in that the concept is trivial, but it might lead to important information which one could not otherwise deduce.

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  4. The weak anthropic principle (WAP) has seen itself in a number of forms. Bethe argued the sun must be powered by nuclear fusion because the then standard idea of solar energy from gravitational collapse. That could only sustain energy production for 100,000 years. Geology and paleontology indicated a far more ancient Earth. Hoyle similarly argued there must be this 18MeV resonance that permitted 3He^4  C^12. Without that carbon would be rare in the universe. In the WAP the occurrence of biology means conditions must be maximal for its occurrence.

    The strong AP (SAP) is more difficult to assess. In some ways this might be thought of as the ultimate unitary bootstrap hypothesis. It could be the ultimate Wheeler delayed choice experiment (WDCE). In the WDDCE if one detects whether an electron passed through one of the slits in a double slit experiment after it did so this serves to collapse the wave function. So a measurement now determines something about the state then. By measuring physics of the earliest universe we may be selecting the state of the universe. So the only physically real cosmologies are those that bring about intelligent observers in them. The other cosmologies might then just be virtual quantum cosmological states.

    The prospects for determining anything about this would lie in some understanding of a type of quantum gravitational lamb shift with these virtual cosmologies. This is of course a very tough call.Even if we were able to detect that this would not be a sufficient condition for SAP. So the SAP may simply be unverifiable.

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  5. I'm puzzled. It is certainly reasonable to say if the universe had been different, we would not be here. In that case, the causal arrow points in the right direction. To say much of anything else makes me think that because eyeglasses exist, we have noses. Or because the man played his lucky number in the lottery, he won a million dollars/euros.

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    1. i think your problem is with the word "because." it is not being used to mean causation, but to mean deduction. eyeglasses don't cause noses, but their design implies something like a nose or they would not be functional. and in the same sense, yes, "because" the man played his lucky number and that number happened to be the winning one, he got the money. his choice did not cause the result, but it did benefit from it.

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    2. '...the man played his lucky number and that number happened to be the winning one,..." thus proving that the man's lucky number was, in fact, lucky.

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  6. Not a fan. Do the prime numbers and Platonic solids and exceptional Lie groups depend on us to exist? No. Why should other laws underpinned by math have anything to do with us?

    I find a third version of anthropism compelling. We may very well be alone in the universe. Certainly, it is extremely unlikely that we are ever going to be able to explore even our own neighborhood with any ease. Relativity just doesn't allow it. Even if it were easy to get going really fast and take advantage of time dilation, everything we left behind would be gone when we returned. And under those circumstances, the only people to leave would be those with nothing to come home to anyway.

    I do not find numerical arguments that other civilizations must exist, just because they are so many stars for them to inhabit, compelling at all. It is no more or less likely that it's just us, and no other sentient species anywhere else. Until there is some actual evidence for even 1 more example, you can't say anything about it.

    Given that we may very well be alone, my form of anthropism says we should take better care of our home and our neighbors.

    -drl

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    1. There are replies to each of your objections.

      "Certainly, it is extremely unlikely that we are ever going to be able to explore even our own neighborhood with any ease. Relativity just doesn't allow it."

      There are things such as multi-generation colony ships, as well as non-biological exploration via such things as von Neumann machines.

      "Even if it were easy to get going really fast and take advantage of time dilation, everything we left behind would be gone when we returned."

      This assumes the goal is to return. The first Amerindians didn't go back to Siberia, nor did the Mormons who trekked from Nauvoo to Utah. It also makes assumptions about the development of civilizations. What of a species like Harry Turtledove's The Race that remains technologically and culturally stable over periods approaching 10^5 years? You could leave and come back 2000 years later to find that fashions and literature haven't changed by much.

      "I do not find numerical arguments that other civilizations must exist, just because they are so many stars for them to inhabit, compelling at all. It is no more or less likely that it's just us, and no other sentient species anywhere else."

      If one sees the emergence of life and sentience as essentially a random process, than more chances must perforce lead to more civilizations. Current estimates are on the order of 10^24 stars in the observable universe. That's a lot of lottery tickets.

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    2. "The first Amerindians didn't go back to Siberia.." And how do you know this? It seems likely to me that some did. As to Mormons returning to Navoo, it is to this day a popular tourist destination for Mormons. They return all the time.

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    3. It is mostly likely that if we explore extrasolar planets, say within 25 light year radius, it will be with probes and robots. It is less likely humans will travel to other stars. Multi-generation spaceships would have to be enormous behemoths. I read that for a crew to maintain itself on a genetic basis without founder effects of inbreeding the crew would have to be at least a few hundred people at the start. The spaceship, an interstellar ark of sorts, would also have to be a sort of closed ecosystem. The biosphere attempt over 20 years ago in Arizona with an enclosed living space ran into trouble within months and eventually they had to open it up lest the inhabitants, numbering around a dozen, would suffocate. Sp the interstellar ark would be an economic and techology challenge thousands or millions of times larger than the proposed FCC collider.

      If the sun is considered to be modeled as a sphere of one cm in diameter Earth would be a nearly invisible speck around 1.5 meters away. The moon would be an invisible bit a few millimeters away from Earth. Jupiter would be around 8 meters away, Saturn 16 meters away and the Kuiper belt outer solar system would extend out some 100 meters. That is the extent of an average football field or pitch. The nearest stars would then lie out at over 400km away. A trip from Boston to New York or Frankfurt to Brussels might about fit that model. There is a lot of space out there! It is also likely that if people were to travel to other stars that the nearest within say 5 or 10 light years are not a good option. So the travel distance and time is formidable.

      Warp drives and other exotic propulsion ideas are not likely. The problem is that they violate the Hawking-Penrose energy conditions. This means with a negative vacuum energy quantum field theories are not necessarily bounded below. Dyson made the observation that if the electric charge were imaginary valued that the electrostatic potential between electron and positrons in a virtual pair would change sign. This would then generate a nearly infinite gush of radiation. The anti-de Sitter spacetime is of this nature, and it may with this instability and AdS would gush out lots of de Sitter spacetimes. There are then likely obstructions to our ability to develop exotic propulsion systems common to science fiction narratives. It does point to a serious problem on what conditions the global causality structure of relativity imposes the same on the local theory of GR, and how quantum gravitation has some super selection of states for this to happen. The Hawking-Penrose conditions are some indicator of this obstruction.

      As an somewhat elementary exercise it is not hard to show that if we were to find magic tech to travel faster than light that based on our average 2% economic and energy growth rate we would consume the entire observable universe in around 6000 years. Fermi's paradox seems answered; it is not possible.

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    4. @drl, I agree, it seems a lot like the mathematical philosophy of Constructivism which has its proponents but there also other valid approaches such as formalism or platonism...just depends on your viewpoint which is why it's hard for me to consider as a part of physical science. I think Hoyle could have as easily made the argument that a resonant structure exists because there was nothing prohibiting its existence and it would have been as valid as the existence of life.

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    5. I believe that humans can become eternal travelers by transferring their consciences to another format; It begins by gradually replacing neurons with chips that in turn are coupled to a computer, it is expected by an adaptation process to continue replacing neurons, once the replacement process is finished, the new brain can be integrated into a device adapted to outer space. More than a trip would be a way of life. Tremendous fantasy but who knows?

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    6. The anthropic principle enabling our existence is interesting, but Lawrence Crowell's comments provoke a hilarious thought that there is an anti-anthropic (so to speak!) principle - ie: relativity, Hawking-Penrose - also at work that keeps us at home. Just so that we don't overrun the universe. Not a bad conservation precaution!

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  7. Not surprisingly, I agree with Steven Weinberg:" Some physicists have expressed a strong distaste for anthropic arguments. This is understandable.Theories based on anthropic calculations certainly represent a retreat from what we had hoped for: the calculation of all fundamental parameters from first principles. It is too soon
    to give up on this hope, but without loving it we may just have to resign ourselves to a retreat." (arXiv 0511037). In any event, long ago I read a book by Barrow and Tipler, The Anthropic Cosmological Principle (1986). More recently, I re-read the book. The book, while interesting, ultimately leaves me dissatisfied--too much speculation. I do not know how to define "a good scientific principle," but for my tastes, this is a retreat that has gone too far. I like what John Donoghue writes: " 'Anthropic' and 'Multiverse' are not themselves the theory, but rather the output of a full theory. Our duty as scientists is not to give up because of this, but to find other ways to test the original theory." (2007, Fine-Tuning Problems of Particle Physics and Anthropic Mechanisms).

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  8. I often see the anthropic principle formulated in terms of "we", but I think the full version should start from "I". There's an additional step where you need to explain why you're part of a sentient species rather than a lone mind, and the anthropic answer is that minds are apparently most likely to evolve in living creatures, and evolution requires species of many individuals. I guess this additional step isn't mentioned either because it sounds too much like solipsism, and the principle can work with the "we" formulation anyway.

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  9. I believe Carlo Rovelli once said that there is no person on Earth who could calculate chemical properties from standard model. Hence, no one could tell us that any form of life would or would not be possible. Then how does this fit together with the anthropic principle? It seems to me that these constraints would be life form dependent, therefore not unique.

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  10. @Sabine Hossenfelder: “...why is the anthropic principle so controversial? It is controversial because it is often brought up by physicists who believe that we live in a multiverse, in which our universe is only one of infinitely many. In each of these universes, the laws of nature can be slightly different. Some may allow for life to exist, some may not.”
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    Sabine, first of all, as to this “multiverse” business, how does something qualify being called a “universe” if it does not contain suns, and planets, and life? Please describe such a thing, and why it would merit the title of “universe.”

    And secondly, I have yet to hear of a final and irrefutable argument that consciousness plays no role in the collapse of the wave function.

    In which case, if it is even remotely possible that consciousness is somehow necessary for causing the ever-propagating quantum waves to become “positionally-fixed” at any given moment in order to display a phenomenon that the waves encode...

    (similar to how a laser is necessary to explicate a three-dimensional image from the coded information in the photographic plate of a laser hologram)

    ...then minus any form of life or consciousness, wouldn’t the universe simply exist in a purely “noumenal” context (i.e., as superpostioned fields of coded information)?

    And that brings me back to the multiverse issue.

    Because if it is possible that a universe requires the presence of life and consciousness in order to explicate phenomena from noumena,...

    ...then how in the world could a universe that has no life or consciousness within its makeup be qualified for the title of “universe” if there are no positionally-fixed objects within it bounds?

    I mean, what would such a phenomenonless (again, purely noumenal) entity even be? - Certainly not a “universe” (not in my book, anyway), and certainly not worthy of membership in a multiverse.

    Now, in regards to the “Anthropic Principle,” logically, the universe does not need us humans.

    However (and speculatively speaking, of course), if a universe wants any of the features encoded in its fields of quantum information to be seen, or felt, or heard, or smelled, or tasted,...

    ...then the presence of life and consciousness (in some form or other) is essential in order to transform those features from their noumenal context into their phenomenal context.

    How can that not be obvious?

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    1. Keith D. Gill wrote to Sabine:
      >And secondly, I have yet to hear of a final and irrefutable argument that consciousness plays no role in the collapse of the wave function.
      ...
      >...then minus any form of life or consciousness, wouldn’t the universe simply exist in a purely “noumenal” context (i.e., as superpostioned fields of coded information)?

      Keith, I assume you know that lots of physicists have had the same thought? Check out Wigner's thoughtful contribution to the book edited by I.J. Good, The Scientist Speculates.

      The problem is how do we decide if that idea is true or is simply nonsense?

      For my part, I seem to be in a quantum superposition between thinking consciousness obviously plays a role in QM and thinking it obviously does not!

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    2. PhysicistDave wrote:
      “Keith, I assume you know that lots of physicists have had the same thought?”

      Sure. Reading the philosophical ideas of many quantum physicists is where I came across such a notion in the first place.

      PhysicistDave wrote:
      “Check out Wigner's thoughtful contribution to the book edited by I.J. Good, The Scientist Speculates.”

      Thanks for that, Dave.

      Yes, and I’m guessing that Wigner’s theories helped to fuel the impetus that drove the “consciousness creates reality” meme in the prior century.

      PhysicistDave wrote:
      “The problem is how do we decide if that idea is true or is simply nonsense?”

      That’s where those of us who fancy ourselves as being metaphysicists (as opposed to plain old physicists), go where the latter refuse to set foot.

      Based on my own wanderings into areas that many physicists avoid, I have come to the conclusion that the idea of “collapsing” wavefunctions is not very helpful when it comes to visualizing how consciousness might be involved in the manifestation of reality.

      As an alternative, I personally believe that reality is “holographic-like” in nature.

      In other words, just as the laser hologram requires the conjoined (tandem) relationship between a laser and that of the patterns of information encoded in a photographic plate in order to create (more at “explicate and reveal”) a three-dimensional image...

      ...likewise, so does the universe require the conjoined relationship between consciousness and the quantum in order to, again, “explicate and reveal” the three-dimensional phenomena encoded within its informationally-based underpinning.

      More specifically,...

      (and again, as an alternative to the “collapse” interpretation, and especially to Everett’s “Many Worlds” nonsense)

      ...I suggest that whatever the mechanism is that decodes and transforms fields of information into revealing the three-dimensional structures of our dreams when we direct our consciousness inward while asleep...

      ...is the same fundamental mechanism that decodes and transforms fields of information into revealing the three-dimensional structures of the universe when we direct our consciousness outward while awake.

      PhysicistDave wrote:
      “For my part, I seem to be in a quantum superposition between thinking consciousness obviously plays a role in QM and thinking it obviously does not!”

      Ha! Very funny.

      Well, at least you’re not sealed in a box with an isotope and a vial of poison.

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    3. I originally read that a "quantum superstition."

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    4. the wave function does not collapse, it is the consciousness that collapses and is left with an interpretation of the subjectivist facts and easy to sell in magazines

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    5. Luis wrote:
      “the wave function does not collapse, it is the consciousness that collapses and is left with an interpretation of the subjectivist facts and easy to sell in magazines”

      Hi Luis,

      Let’s look at this from the perspective of the Double Slit Experiment, more specifically, the instance where single electrons are shot through the slits one at a time.

      By reason of the fact that an interference pattern appears on the detection screen after a series of single electrons are shot through the device, it means that something* with respect to each individual electron spreads-out into a wave and propagates in accordance with the Schrödinger wave equation.

      *(We’re talking about something “real” here that obviously has a direct and measurable influence on matter, as opposed to some kind of mathematical abstraction.)

      And once that waving “something” arrives at the screen in the form of a tiny impact spot, it thus means that the particular wavefunction that determined where the electron landed on the screen has indeed collapsed (i.e., stopped doing what it was doing in the space between the slitted wall and the screen).

      So, no; consciousness is not what is collapsing in that situation.

      However, there is still a mystery as to what it is that is actually waving.

      Is it the fabric of the electron itself that spreads-out into a wave and interferes with itself? Or is it something else altogether? Theories are put forth, but no one seems to know for certain.

      Perhaps Sabine could offer her opinion on this?

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    6. I said "consciousness collapses" in a metaphorical sense, something like "we stay with our mouths open"; but the electron is always a wave and never ceases to be, even when it goes through 10 grids consecutively; the problem is that this is not independent of space and is linked to it, and its wave function must have several components linked to space, in an action-reaction process; notice that I am considering that space is matter too, with its own organization and energy and geometry and the rest are asymmetries within it. a greeting

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    7. I would like to argue against referring to Hugh Everett's theory as "nonsense." Please return to July 1957 and read (or re-read) his original paper. The paper itself is brilliant. John Wheeler emphasizes (in his "assessment") that "the relative-state theory does not pretend to answer all the questions of physics." (page 465). Another point to stress, and Heisenberg already stressed it in 1930: "the reader must be warned against an unwarranted confusion of classical wave theory with the Schrodinger theory of waves in a phase space." (Principles of Quantum Theory, preface and page 47).

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    8. Gary Alan wrote:
      “I would like to argue against referring to Hugh Everett's theory as "nonsense." Please return to July 1957 and read (or re-read) his original paper. The paper itself is brilliant.”
      ----------------
      Hi Gary,

      Hugh Everett’s original paper may indeed be brilliant, but that’s not what I have a (pet-peeve) problem with.

      No, what bothers me is the popularized “branching worlds” nonsense encapsulated in Bryce Dewitt’s interpretation of Everett’s work.

      As you probably know, Bryce Dewitt is the theoretical physicist who coined the term "many-worlds" and was an early and avid champion of Everett's Theory.

      In an article for the magazine, Physics Today, Dewitt stated the following:

      “...I still recall vividly the shock I experienced on first encountering this multiworld concept. The idea of 10 to the 100+ slightly imperfect copies of oneself all constantly splitting into further copies, which ultimately become unrecognizable, is not easy to reconcile with common sense...”

      As one minor example of the scale of this branching process, realize that the Many Worlds Interpretation implies that trillions of copies of ourselves,...

      (along with trillions of copies of the entire universe)

      ...literally spring into existence by reason of the infinitesimal quantum events that take place within the context of the light waves we encounter as just one of us gazes at our computer screen for a couple of seconds.

      Please forgive me for belaboring this, but just let that sink in.

      Again, that’s trillions of autonomous universes branching-off of our universe by just - ONE OF US - looking at our computer screen for a couple of seconds; never mind the almost infinite number of other quantum events taking place, each and every second throughout the rest of the universe.

      Now in light of the preceding, it doesn’t require a lot of mind power to envision that the *MWI* clearly suggests that ultimate reality consists of an exponentially-expanding, never-ending - EXPLOSION - of new bubbles of reality (new branching universes) that not only continuously and instantly “effervesce” from the bubble of our universe,...

      (think of popping the cork of a shaken bottle of champagne)

      ...but also from the instantaneous foaming/bubbling (branching) that would - IMMEDIATELY OCCUR - as an infinite number of our doppelgangers gaze at their own computer screens within the confines of each subsequent and autonomous universe...

      ...(trillions of which just came into existence in the time it took you to read this parenthetical sentence).

      Now I don’t know about you, Gary, but to me, the idea that the intricate details and fantastically complex workings of our universe...

      (not to mention, our unique individualizations of personal consciousness)

      ...could simply be duplicated in such a willy-nilly fashion on such an unfathomable scale, is the most outrageous bucket of codswallop I’ve ever heard of.

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    9. Gary,

      Perhaps Keith was unfair in referring to the Everett many-world theory as "nonsense."

      But it has some severe technical problems: notably what are referred to as the "probability measure" and "preferred basis" problems. From time to time, MWI enthusiasts come up with proposed "solutions" to those problems.

      But their "solutions" seem only to convince people who already believe in MWI.

      A bit like theology.

      By the way, there are other problems with MWI: the whole "universe splitting" thing is wrong. All of the branches of the wavefunction are already there in some sense: the number cannot increase over time. Sabine has some other objections, which I am not sure I fully understand.

      Would you like it better if everyone just said that MWI is highly problematic?

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    10. Keith D. Gill and Physicist Dave, what a delight it is for me to read two thoughtful replies to my reply ! I do appreciate these interactions. Not that my opinion matters, but, I really am not a full-fledged MWI proponent. On the other hand, I do not want to downplay what Hugh Everett achieved. As Bryce Dewitt wrote (Physics Today 1970): "By showing that the formalism alone is sufficient to generate interpretation, it has breathed new life into the old idea of direct correspondence between formalism and reality." Bryce Dewitt writes: "let us try to take the mathematical formalism as it stands, to deny the existence of a separate classical realm, to assert that the state-vector never collapses." Those are three things I admire about the entire enterprise !

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    11. Gary,

      I actually read the deWitt book, The Many Worlds Interpretation of Quantum Mechanics, way back in the mid-70s, not too long after it came out.

      It was certainly thought-provoking.

      It can be a good exercise to ask any physicist, "So why do you reject MWI?" I think you'll get lots of different answers.

      One issue that only recently occurred to me -- this may be the point Sabine has been trying to get across -- is that we spend a lot of time talking about the math of measurement when we teach QM: Hermitian matrices represent observables, eigenvectors correspond to states with definite values of the observable and the value observed is the eignevalue, etc.

      So, how does all of that somehow come out of MWI?

      I don't recall that every being explained clearly.

      By the way, almost everyone agrees that somehow all this stuff is tied up with the concept of "decoherence" (exactly how is not so clear!). A lot of real technical work has been done on dechoherence in recent years: Schlosshauer's Decoherence and the Quantum-to-Classical Transition is a good (albeit exhaustitng!) overview (thanks to Peter Woit for bringing the book to my attention).

      I'm happy to say that there does seem to be a growing view among physicists that there is indeed something we really do not understand about quantum mechanics.

      All the best,

      Dave

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    12. Dave, thanks for your reply, I enjoyed reading it. I rather agree with Eugene Wigner: "It appears that the statistical nature of the outcome of a measurement is a basic postulate, that the function of quantum mechanics is not to describe the nature of 'reality,' whatever this term means, but only to furnish statistical correlations between subsequent observations." (page 286, Wheeler and Zurek, Quantum Theory and Measurement, 1976 Lectures Princeton). As far as Everett is concerned, he concludes of his theory: "it can be said to form a meta-theory for the standard theory. It transcends the usual standard 'external observation' formulation, however, in its ability to deal logically with questions of imperfect observation and approximate measurement." (RMP 1957). Of Bryce Dewitt, what can I say ? He was such an awesome intellect and I still do not delude myself into thinking that I fully comprehend him (or, Everett). The only text I have read regards decoherence is the excellent: Interpretation of Quantum Mechanics, Roland Omnes (1994).

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    13. Gary Alan,

      You quote Wigner:
      >I rather agree with Eugene Wigner: "It appears that the statistical nature of the outcome of a measurement is a basic postulate, that the function of quantum mechanics is not to describe the nature of 'reality,' whatever this term means, but only to furnish statistical correlations between subsequent observations."

      The real problem is not the statistical nature of QM: all physicists know that a statistical theory can be an approximation to an underlying deterministic theory (as is true in classical statistical mechanics).

      The real problem is Bell's theorem, which is, of course, just a formal mathematical version of the EPR paradox.

      Bell's theorem seems to show that any underlying realist theory that is the basis for QM must violate special relativity.

      Logically, as Sabine has emphasized, there are some conceivable loopholes to Bell's theorem: e.g., super-determinism (Sabine's current favorite, I take it) or retro-causation (which may turn out to be equivalent to super-determinism). But no one has figured out how to make either of those work in detail (I am one of those who has failed, so far at least).

      Or, of course, we could just say, "Okay, special relativity is just not true at the fundamental level -- live with it." That, in effect, is what Bohmian mechanics does, and there are other alternatives that do the same thing -- Ed Nelson's "stochastic mechanics" as well as some (unpublished) models I myself have worked out.

      The problem is that special relativity works so incredibly well, it is hard to explain why that appears to be the case if special relativity is actually worng at the more fundamental level.

      'Tis a puzzlement.

      Dave

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    14. Thanks for the thoughtful reply, Dave. After reading it, and curious about superdeterminism, I downloaded a pdf copy of Gerard t'Hooft "Cellular Automaton Interpretation of Quantum Mechanics." (2016, Springer). He writes: "It is here that our present theory is more accurate, if we knew the wave function of the universe exactly, we would find that it always evolves into one classical state only, without uncertainties and without superpositions." (page 81). I ask: How could one ever know the 'wave-function of the universe' exactly ? Still, this appears to be a fascinating and well-written book, I will spend time studying it.

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  11. As far as Hoyle's prediction goes, Helge Kragh has a paper titled "An anthropic myth: Fred Hoyle’s carbon-12 resonance level." Here's the abstract:

    The case of Fred Hoyle’s prediction of a resonance state in carbon-12, unknown in 1953 when it was predicted, is often mentioned as an example of anthropic prediction. However, an investigation of the historical circumstances of the prediction and its subsequent experimental confirmation shows that Hoyle and his contemporaries did not associate the level in the carbon nucleus with life. Only in the 1980s, after the emergence of the anthropic principle, did it become common to see Hoyle’s prediction as anthropically significant. At about the same time mythical accounts of the prediction and its history began to abound. Not only has the anthropic myth no basis in historical fact, it is also doubtful if the excited levels in carbon-12 and other atomic nuclei can be used as an argument for the predictive power of the anthropic principle.

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    1. sabine's article seems to imply the basis of the inference was the prevalence of carbon, not life per se. if so, a weak example of a weak anthropic principle.

      Delete
    2. "a weak example of a weak anthropic principle."
      Or just causality. Here's a lot of carbon, I wonder where it came from.

      Delete
  12. I think there is a problem with the comparison of a cosmology with a large negative cosmological constant and another with a large positive cosmological constant. A universe with a large negative cosmological constant would be an anti-de Sitter spacetime, or something similar. The achronal region of the Taub-NUT spacetime would also fit. This does not so much collapse as it has closed timelike curves. The relevant physics one works with in an AdS are within a conformal patch that avoids these strange issues. A universe with a positive cosmological constant and a lot of gravitating matter can recollapse.

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  13. "The best-known historical example for the use of the weak anthropic principle is Fred Hoyle’s prediction that a certain isotope of the chemical element carbon must have a resonance because, without that, life as we know it would not be possible."

    It is simply not true that this is an example of the anthropic principle.

    Hoyle's prediction was based on the unexplained preponderance of carbon in the universe, not the arrangement of a small amount of that carbon in the shape of human beings. You can have a lot of carbon, and not have human beings (e.g. if the asteroid hadn't hit and wiped out the dinosaurs).
    The anthropic principle is a complete misnomer. This could very easily have been a universe without human existence, and you have no idea what the physical possibilities are for life and universes. All we know is that humans exist in a miniscule bit of this universe. There's nothing else useful to be said i.e. it's "philosophy".

    There have been zero scientific discoveries based on the anthropic principle. So far and completely unsurprisingly, it has proven useless.

    " If you believe in the multiverse"

    There is zero empirical evidence for the multiverse, so if you believe in the multiverse you are delusional.

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    1. Steven,

      As I said, physicists don't usually draw on the existence of human life, but preconditions for life.

      Delete
    2. Sabine Hossenfelder 12:29 AM, December 07, 2019

      But Hoyle's successful prediction was simply motivated by the sheer amount of carbon in the universe which was unexplained. The fact that carbon is important in the life forms we know of is neither here nor there.

      So it is not an example of a successful application of the anthropic principle. There are none in science.

      (And saying it is an example of the anthropic principle doesn't help with the ongoing attempts to educate the religious savages.)

      Physicists are not going to determine anything about the tiny soup of quarks 13.7 billion years ago by considering life forms. It would be like trying to reverse engineer an ARM CPU by viewing cat videos on YouTube.

      We don't know what life forms are possible in totality. We don't know what universes are physically possible in totality. So nothing sensible can be said about the constraints of life on physics.

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    3. Steven,

      As I said, physicists don't usually draw on the existence of human life, but preconditions for life.

      Delete
    4. Sabine Hossenfelder 2:13 AM, December 07, 2019

      You claimed that Hoyle's prediction was based on the idea that carbon was needed for life, and is therefore an example of an application of the Anthropic Principle.

      This is absolutely not true, then or now. Hoyle made his prediction based on an unexplained, large amount of carbon in the universe. That's it. Nothing to do with life, just a lot of carbon.

      Nobody knows what the pre-conditions for "life" are and considerations of these kind of ideas has led to a grand sum of zero scientific facts. Surprise, surprise.

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    5. The "anthropic principle" can't explain anything.

      We only can exist because we can exist. YES! But we has not to exist because we can exist. BAD!

      I don't see any surplus value in such considerations.

      And what do us say this sentence: "If you believe in the multiverse, ..."?

      Science is the new playground for useless people. (In ancient times this had been the churches.)

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    6. Steven,

      As I said, physicists don't usually draw on the existence of human life, but preconditions for life.

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    7. weristdas,

      The Anthropic Principle itself does not "explain" anything, it is using an observation (humans exist) to obtain constraint on the laws of nature. It is the laws that do the explaining, not the principle used to derive them. The same is true for any other "principle" that physicists use to formulate hypothesis.

      Delete
  14. This comment has been removed by the author.

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  15. The anthropic principle is the most meaningless (anti) logical idea ever proposed.

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    1. Thommy,

      It is because of opinionated but uninformed opinions like yours that I made the video.

      Delete
  16. Well said. The mystery is not whether the anthropic principle exists, but why it exists. Less fearful and more precise surveys of anthropic phenomena could someday lead to theories that generate meaningful experimental questions.

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    1. "anthropic phenomena"
      What anthropic phenomena? This kind of AP speculation has never led to a single scientific fact and for good reason.

      "theories that generate meaningful experimental questions."
      You think the structure of complex life forms that are the result of billion years of biological evolution can shed light on fundamental physics? We're a long way up the stack from the substrate.

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  17. I have been under the impression that the anthropic principle is controversial in significant part because if there is only one universe, the fact that it seems so incredibly improbably fine-tuned to support life suggests there is a God who designed the universe. That suggestion has gotten a lot of people's hackles up. By some accounts, the odds are infinitesimally small that the universe's various constants and parameters would be just what they need to be to support the evolution of life. But then the multiverse theory rides in to save the day. After all, if an infinite number of universes exist, then the improbability of our own universe's existence need not suggest to us the existence of a designer God. One need only consider that among an infinite number of universes, a few by pure random chance are bound to be fine-tuned to support life. Thus whatever its merits or demerits, multiverse theory seems to have as a sort of subtext a defense of science against belief in a biblical designer/creator God and all that goes with such belief. I don't think science generally needs to defend itself against belief in a creator God, but I suspect some multiverse theorists, contemplating the incredibly unlikely fine-tuning of our anthropic universe do think such a defense is necessary and find in multiverse theory, over and above whatever scientific merits it may have, a reinforcement of the bastions of science against what some of those theorists consider to be the dark superstition of religion. The multiverse theory is in part an attempt to undermine what might otherwise seem a bit too religiously miraculous: our universe.

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    1. Ed U.

      Yes, that many people have this false impression is the reason I made this video

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    2. Ed U.2:28 AM, December 07, 2019

      "I have been under the impression that the anthropic principle is controversial in significant part because if there is only one universe, "
      The anthropic principle has no explanatory power in science. No scientist has ever discovered any fact based on its application.

      "the fact that it seems so incredibly improbably fine-tuned to support life"
      There is zero empirical evidence that the universe is fine-tuned, for life or anything else. The universe has been observed to work, roughly at least, according to certain laws and constants and nobody knows why they are what they are. It is not known how common life is in the universe. So to claim it is fine-tuned *for life* when it appears to be mostly dead doesn't make sense.

      "suggests there is a God who designed the universe."
      There is no evidence that the universe is designed. It has been observed to be how it is and nobody knows why. Every observation so far in science has only shown natural development of the universe. Science has reduced the question of where 100 billion galaxies came from to the question of where a tiny soup of particles came from. So you don't need to worry about life, that's explained, just the tiny soup of particles. There's no reason to think that was necessarily designed. "Gods" are fictional beings like orcs and wizards. They only ever appear in fairy tales. As an adult, you shouldn't really be believing in fairy tales.


      "That suggestion has gotten a lot of people's hackles up. "
      Hackles are raised by people who believe in primitive superstitions trying to deliberately corrupt science with unscientific nonsense using unscientific methods. The standard of truth in natural science is observation. You can't just make stuff up.

      There is also zero empirical evidence of a multiverse.

      "the dark superstition of religion"
      Organised religions tell ignorant people lies and take their money from them. This is called criminal fraud. The Pope and the Archbishop of Canterbury should be arrested like the mafia bosses they are. Religion is based on superstition, yes. Completely delusional.

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    3. Ed U: Just consider the inverse of your claim, and everything is explained: Life is incredibly fine-tuned to the laws of the universe. By virtue of evolutionary optimization to exploit pre-existing laws to their limits, since the laws cannot be violated.

      God didn't design the universe for life, by random recombination of chemicals life began to exist in the universe, and evolved to fit as closely as possible to whatever the rules of the game happened to be.

      And as Dr. Hossenfelder has been pointing out for years, "fine tuning" is meaningless because there is no proof anywhere that any of the constants of the universe can be any different than they are.

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    4. Thanks Dr. Castaldo for advancing my thoughts on this question, though I don't know if you are correct. Your last sentence seems to me your key point. Your first two paragraphs would not be relevant unless your last sentence is correct. Because if the constants could be different in an infinite number of ways prohibitive for the evolution of life, then the comment of mine to which you respond remains unanswered.

      Here's another question: if it's true that the universe's constants must be as they are (i.e., such as are not prohibitive for the evolution of life), does that not still seem remarkably improbable? Perhaps it is not, but I'm not sure.

      And is it the case that we have no proof that the constants of the universe can be any different than they are, but also that we have no proof that the constants must be as they are? How do we know that the constants must be as they are? We know, more or less, that they are as they are, but how do we know that they must be as they are? Is there scientific consensus that they must be as they are? Or is that always bound to be speculation?

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    5. If I ever heard of one physical constant getting tuned to even a slightly different value I would take this stuff more seriously. It seems like a highly elaborated version of the tried and trusted "we don't understand it but we can make up some good stories" approach to uncertainty. It's mot really that different to angry gods throwing lightening bolts, etc.

      Delete
    6. Ed U.1:09 PM, December 07, 2019

      "Because if the constants could be different in an infinite number of ways prohibitive for the evolution of life,"

      It is not known that they can be different at all. There is one observed example of the universe and one measured value for each constant - that's all that is known coz that's all been observed. People who talk about "if the constants were different" are talking out of their hats. **Natural science is observation - that's it**

      "if it's true that the universe's constants must be as they are "
      This is not known either. It is known if they can be otherwise or if they must be as they are. It is just known that they can be as they are, because they are. As soon as you wrote "if" you left science.

      "does that not still seem remarkably improbable?"
      There is ***zero*** information on probabilities of values of constants because there is only one data point. Throw a die once. It lands on a 6. Is it a fair die? Is it a loaded die? Dunno with only one data point.

      "And is it the case that we have no proof that the constants of the universe can be any different than they are,"

      Yes, of course. We can only see the 1 universe. There are no "proofs" in natural science, just observations.

      " but also that we have no proof that the constants must be as they are? "

      Yes, no empirical evidence that they must be as they are.


      "How do we know that the constants must be as they are? "

      We don't. We only know they can be as they are, because they are as they are.

      "We know, more or less, that they are as they are,"

      Spot on. So why were you going on about fine-tuning in the first place?

      "Is there scientific consensus that they must be as they are?"
      Nobody has produced any empirical evidence except that they are as they are. There is no empirical evidence that they can be otherwise nor that they must be as they are.

      "Or is that always bound to be speculation?"
      Nobody knows, but no sensible scientist would research this kind of speculative nonsense.

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    7. It is worth noting that there have been, and will continue to be, experiments and observations aimed at identifying and characterizing the extent to which certain constants do, in fact, change.

      For example: Mota&Barrow (2003) "Local and Global Variations of The Fine Structure Constant"
      https://arxiv.org/abs/astro-ph/0309273

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    8. JeanTate2:37 PM, December 08, 2019

      "It is worth noting ..the extent to which certain constants do, in fact, change."

      If they do change they are not constants. But the constants are just a proxy for the "nature of the universe". And the nature of the universe is not known to be fine-tuned for life or anything else.

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    9. "...by random recombination of chemicals life began to exist in the universe, and evolved to fit as closely as possible to whatever the rules of the game happened to be."

      Exactly. Even if there were other "universes" with different rules, the same process could be at work producing life as we don't know it, for obvious reasons.

      Delete
  18. The Anthropic Principle is just as scientific as the Dinosauric Principle.

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  19. Sabine,

    The late physicist Victor Stenger argued that the Hoyle argument was actually much looser than often thought.

    I'm not in a position to judge Stenger's argument (it's been a long time since my one quarter of nuclear physics!) and you have probably addressed this in the past, but I thought I'd mention it here for completeness.

    All the best,

    Dave

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    1. Dave,

      Really Stenger is missing the point. The anthropic principle doesn't say anything about fine-tuning (and neither did I). Are there other theories you can think of that would remove the need for that particular C12 resonance? Almost certainly. Does that invalidate the point that the observation that we exist puts constraints on the hypotheses you can put forward about the laws of nature? No, it doesn't.

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    2. "Does that invalidate the point that the observation that we exist puts constraints on the hypotheses you can put forward about the laws of nature?"

      It has nothing to do with Hoyle's prediction. Nobody knows if his C12 resonance is required for life to exist in the universe. This is not a known anthropic constraint. The resonance was predicted to explain a lot of carbon.

      "Does that invalidate the point that the observation that we exist puts constraints on the hypotheses you can put forward about the laws of nature? "

      In a very broad and practically useless sense, which is why AP has led to no scientific facts and never will.

      Delete
  20. Sabine wrote to me:
    >Does that invalidate the point that the observation that we exist puts constraints on the hypotheses you can put forward about the laws of nature? No, it doesn't.

    True enough. As a matter of logic, your description of the valid and invalid uses of the anthropic principle is correct.

    But I think it is still an interesting question whether in practice there actually has been a valid use of the anthropic principle. You referred to Hoyle's C12 argument, and I agree that this is surely the most famous and plausible use of a valid anthropic argument.

    But if Stenger was right that even the Hoyle argument is pretty shaky...

    Well, maybe a valid anthropic argument is possible in principle but one has never actually been seen!

    Any nuclear physicists in the house?

    Again, my expertise in nuclear physics is so minimal that I am not claiming that Stenger is in fact correct. But the issue is interesting.

    All the best,

    Dave

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  21. The historical precedence for the weak anthropic principle (WAP), such as Hoyle's argument for an 18MeV resonance that permits 3He^4 → C^12, is simply citing how the universe as we observe must have certain properties in order that carbon exists as we observe. While it is the case that Hoyle's argument does not explain life or our existence, it does indicate how there must be a property of nucleons that permits carbon, which in turn permits life. This is then a sort of WAP.

    The WAP based on the existence of intelligent observers in the universe, as cited by our existence if you assume we are really intelligent, just means physical conditions, in particular the coupling constants of gauge fields etc, must be of such a nature that life can exist. For instance if the fine structure constant were slightly different then molecular bonds would have different strengths and it is questionable whether complex molecules of life would exist. This means the renormalization group flows (RGF) for gauge fields must have an IR attractor point that is commensurate with life. With respect to the related issue of fine tuning this means the RGF attractor points for gauge fields are either determined in some absolute way or there is this multiverse where there is an ensemble of possible RFG attractor points. The existence of life would just mean we exist in a cosmology that has an RGF that is commensurate with life and the evolution of life that lead to our existence. The WAP then does not provide a compass bearing on the issue of fine tuning.

    Whether or not life must exist or not is unknown. There is a problem with ribosomes, which are complexes of polypeptides and RNA strands that translate information from messenger RNA strands into polypeptides. It is a sort of molecular compiler. Ribosomes emerged by means unknown, for there are no simpler complexes they could be built from. The probability that ribosomes can spontaneously emerge is exceedingly small, something like 1:10^{10^{10}}. Of course this is at a level where biological evolution is a theory at its “end point,” similar say to general relativity at singularities, and we face a deep question. This also may touch on the question of how Markovian or Gaussian processes give rise to subMarkovian or “pink noise” processes that deviate from Gaussian statistics. It is often said the universe is in some way praedial to the formation of life. It really is not known. It is possible that life on Earth is an immense cosmic fluke. If so there is a weak link to WAP and certainly SAP arguments.

    When it comes to other intelligent life in the universe we may never answer the question about that. I worked some issues with planetary migration, where small planets have their orbits changed by gravity interaction with gas giants in a stellar system. To make a complicated story short I estimated there may only be a few 100 to a few 1000 planets in this galaxy, and presumably any other, that are capable of harboring complex life. There may be plenty of planets with life on its margins, say maybe Mars or now some argue with the interiors of Jovian and Cronian moons, but far fewer with exuberant life such as Earth. This would mean it is not really likely that if any of these planets bring about intelligent life capable of technology they are coincident with us. The nearest ETI on our past light cone might be 50 million light years away, which means we will probably not receive signals from them. The irradiance of EM radiation obeys a 1/r^2 law.

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    1. Lawrence Crowell6:35 AM, December 07, 2019

      "it does indicate how there must be a property of nucleons that permits carbon, which in turn permits life. This is then a sort of WAP. "

      Hoyle saw a lot of carbon and worked out where it came from. End of story. Any talk of the preconditions for life is pure speculation. How do you know how likely life is in a universe with or without the C12 resonance? How do you make generalisations about life given it has only ever been observed in 1 solar system. etc., etc. We only know of 1 physically possible universe, so any talk of Anthropic Principles or fine-tuning is pure speculation which has so far and will continue to lead nowhere.

      " Ribosomes emerged by means unknown, for there are no simpler complexes they could be built from. "

      There are no *known* simpler complexes...

      "The probability that ribosomes can spontaneously emerge is exceedingly small, something like 1:10^{10^{10}}. ""

      So they were driven to emerge by some process like evolution, then. Is anybody really suggesting they emerged spontaneously or randomly?

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    2. With ribosomes, we have no idea how they came about. Now presumably there is some process of molecular selection or a way that statistical mechanics and even quantum mechanics, which are Gaussian or Markovian, give way to subMarkovian or a pink noise process.

      Hoyle's argument did focus on the abundance of carbon, but since carbon defines organic molecules its existence is necessary for life. Hoyle did not think according to any WAP, but as it turns out he did so indirectly.

      Delete

    3. Really with the problem of how the Ribosoma was formed we realize that something very deep we are missing; beyond evolution, beyond a creator

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    4. Luis 10:00 AM, December 08, 2019

      "beyond evolution, beyond a creator"
      So now we're on to Beyond God of the Gaps. You have trumped the religious.
      I don't know what ribosomes are, but I will tell you for nothing that they came about via some chemical or biological process.

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    5. You have the superdense object that produced the universe; Can you deduce human existence from its initial formulation? I doubt it; in each degree of development new properties appear that are not implicit in the lower level; life can only happen in a general framework of organic matter; just as in crystals there are mechanical properties that atoms do not have on their own; so it must happen in the relationships between complex organic molecules; if it is not in that condition that life arises; then look for the plumber

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    6. Luis7:55 AM, December 09, 2019

      And these layers are explained respectively in fields like Physics, Chemistry, Biology, etc. There's no evidence of "beyond evolution", "beyond a creator" or a "plumber" though.

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    7. Steven I said "beyond evolution", "beyond a creator", in the sense that you cannot say "evolution" and solved the problem; the word behaves the same as "creator". I can tell you that explaining how the first cell was formed will be a greater challenge than simply saying "evolution."

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    8. Luis6:18 AM, December 10, 2019

      The universe is explained by the natural structures and natural processes of natural science. Evolution is one of those processes. There is no reason to think that abiogenesis wasn't a natural process, just the evidence is buried billions of years deep so it may never be confirmed. There is no creator and no plumber.

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    9. Mr. Evans, the point I want to reach is that; For example: we have a gas cloud formed mainly of carbon, oxygen, nitrogen, hydrogen, and some other chemical elements; on the other hand we have a beef steak, composed of the same atoms; my question is, if we cannot pass from one form to another with mathematical rigor, not only in each level of development but in each qualitative leap; then we can't talk about fine adjustment; and the anthropic principle would be more like an emotional state, like a "roughly" emotional calculation, which includes what we know and what we don't; without this way of thinking, as we would orient ourselves in the case that our omnipotent mathematics has not included some parameters and drags that fault throughout a development of formulas, or is unable to quantitatively describe the unknown; in other words ; How useful is philosophical thinking?

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    10. Luis4:58 PM, December 10, 2019

      I see.
      So it's too complex to judge exactly how much carbon is required in the universe to support carbon-based life. Thus, one can say that the existence of carbon is anthropic, but the C12 resonance which ensures an abundance of carbon is not necessarily known to be anthropic. This is why the Anthropic Principle is of no use to physics. The fact that carbon-based life requires carbon is not a revelation.

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  22. There has appeared an interesting (open access) paper: "A New Fine-Tuning Argument for the Multiverse" (Friederich, Foundations of Physics, September 2019): "This paper has two aims. First, it points out a crucial difference between the standard argument from fine-tuning for the multiverse and paradigmatic instances of anthropic reasoning."

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    1. In addition, Evans, our claims to build a mathematical description of the universe from its "initial state"; So try to pass mathematically and justifiably from one of these layers to another ?; in other words; describe transitions to new organization of the matter mathematically ?. Our determinism has its weaknesses

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    2. Gary Alan 8:56 AM, December 07, 2019

      "There has appeared an interesting (open access) paper: "A New Fine-Tuning Argument for the Multiverse" "

      It's not interesting, it's yet another failure to understand modus ponens. You can give a billion examples of A(i) => B being true, but unless one of the billion A(i)s is true, you haven't shown B to be true.
      And so with this paper more drivel about if this constant were slightly different or that particle was slightly smaller. We do not know that the universe can be any different.

      The drivel starts in the paper's introduction:
      "The fact that the universe supports life seems to depend delicately on various of its fundamental characteristics, notably on the form of the laws of nature, on the values of some constants of nature, and on aspects of the universe’s conditions in its very early stages. An example of such fine-tuning for life is the difference between the masses of the two lightest quarks: the up- and down-quark [1,2], [3, Sect. 4]. Small changes in this difference would undermine the stability properties of the proton and neutron"

      There is fine-tuning *in* the universe, e.g. pianos are tuned, but the universe itself is not known to be fine-tuned. When will people stop writing nonsense like this paper?

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    3. Luis 6:41 AM, December 10, 2019

      Go and look at quantum chemistry or biochemistry, presumably they have something to say about the boundaries between the fields. The natural way to describe a protein is in biological terms, and to try to describe it in terms of the quantum fields of its constituent particles would be impossible practically, though it is of course ultimately physical. It's a question of complexity. I'm not sure what point you are trying to make. You understand that the universe is described by natural science alone, yes?

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    4. Previously, I wrote that a recent (2019) paper: "A New Fine-Tuning Argument for the Multiverse," was "interesting." It is important to note that I can find a paper "interesting" even if I disagree with its premise or even if it eventually turns out to be wrong !

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    5. I can only tell you that I was educated in an atheist family and school environment, in an atheist country; never in my life have I had to fight against any religious prejudice; nor fight against religious, it is ridiculous to do that; but I am an atheist by presumption; I presume there is a natural cause for everything; but I know we have enough ignorance to be so arrogant; and for that reason I would not ask anyone what their ideological position is; because my "ideological position" does not know what the other 95% of the universe is, as and what was before the big bag, if our universal constants have always been universal or are only a regularity from the big bag to here; when we don't know what is really in a black hole and how the first cell was formed; we have a lot of descriptive science ,some good explanations; but it seems a minuscule part compared to what we ignore. With respect to the evolution of the first cell; Of course, the evolution of a star has nothing to do with it, nor that of the galaxy, even that of species; they are all different types of evolution for different things; the evolution of the cell needs shortcuts; because he has the mathematical odds very much against him, in that sense I think just like Mr. Lawrence

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    6. Gary Alan1:04 PM, December 10, 2019

      True, in general. But this paper is utter drivel from the start. "If the universe could be different, then it could be different." A revelation!

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    7. Luis4:41 PM, December 10, 2019

      "when we don't know what is really in a black hole"
      The matter from a collapsed star and other matter it has sucked in from its surrounds.

      " and how the first cell was formed; "
      There are several theories for abiogenesis, but the evidence is lost under several billion years of churn of the Earth's surface.

      "but it seems a minuscule part compared to what we ignore."
      Natural science has a good grip of what is going on in the observable universe from 14 billion years ago until today.

      " the evolution of the cell needs shortcuts; because he has the mathematical odds very much against him, "
      This simply isn't known to be true. There are lots of natural scientific processes explaining how various natural structures come into being, and there is no reason to think the situation would be any different for the first simple cells. Nothing in the natural world has ever been explained except by natural science. People are welcome to try other methods and announce their results - so far there are zero.

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    8. I realize that in today's science you see a beautiful picture that only needs a touch up; I see clouds and storms everywhere; look at your conformist attitude towards a black hole; I assure you that this simple "collapsed matter" will rethink all science.

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  23. I think the argument re carbon is that humans had to exist in order to detect that there are large amounts of carbon in the universe, so anything deduced from our observations is part of the WAP. Note that this does not suggest a causal relationship between our existence and that of the universe, but rather a causal relationship between our existence and what we can deduce about the universe.

    On the need for consciousness to explain quantum collapse (which has always seemed intuitively false and self-aggrandizing to me), I have asked at several science blogs (e.g., Sean Carroll's) whether an experiment has ever been done to test this: have a detector in the two-slit experiment with the results recorded in a computer file, and before checking for interference patterns, delete the file unread. I have never gotten an answer to this question (that I saw), but in in one of the pop-sci QM books I have read recently ("Beyond Weird", "Through Two Doors At Once", etc.) I finally saw a statement that this obvious experiment had been done and that the results were, as expected, that conscious knowledge of what was detected plays no role. (Good luck to me finding it again, though.)

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  24. Sabine, your distinction of SAP (our existence causes universe) and WAP (our local universe just happens to support conscious life) seems to lose one of the other possibilities: that the universe was created especially to support conscious life. I'm not pushing this view, and I should be the least likely person to even mention it, but from an integrity point of view I believe it should be mentioned as another possibility. I am writing on this general subject at the moment, and I find this possibility keeps resurfacing, no matter how hard I try to kill it off. NB: I do not subscribe to any of the multiverse viewpoints.

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  25. " I often hear people refer to the anthropic principle to say that a certainty property of our universe.."
    Should be "a certain property".

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    1. Mike,

      Yes... Thanks for pointing out, I have fixed that.

      Delete
  26. Hmm. Re the anthopic principles:

    The SAP is clearly nonsense, unless one is into teleological metaphysics. Personally I love teleological metaphysics, but it's got nothing to do with physics or empirical science generally.

    The WAP seems to me to be so trivial as not really to be an independent principle at all: it is merely a special case of the basic empirical principle that theory should be compatible with observed phenonmena.

    The use of the WAP in conjunction with a probabilistic argument to 'explain' phenomena such as the values of fundamental constants, by arguing that these considerations imply the likely existence of some form of cosmological multiverse seems to me to be a fundamentally invalid form of argument.

    It seems to go like this (I can't be bothered to write it formally:

    1. various fundamental constants have values which must be measured and inserted 'by hand' into our equations, and which were they to differ in even the minutest degree would mean life in any recognizable form could not exist (and more dramatic consequences, no stars, no stable atoms etc.)

    2. it is very unlikely that these constants, which could have taken any value, just as a matter of brute fact take values in the minuscule range compatible with life.

    3. therefore we should conclude that it is fact likely that there is a huge number of regions other than the observable universe (presumably of the order of the inverse of how improbable the life-compatible values are in (2)), in which these constants take a vast range of possible values.

    4. given this, we should of course not be surprised that we live in one of the regions that is compatible with our being in it.

    This is just a rubbish argument. Aside from the fact that (2) is nonsense (I'm not trained in physics so correct me if I'm wrong, physicists, but I don't believe that anyone has any idea why these constants take the values they do, so I can't see how we can say they are probable or improbable) the argument wouldn't work even if (2) was true. In (3) you have to postulate the existence of a vast number of regions, and the improbability you introduce here precisely cancels out any improbability you reduce in (2).

    And in any case, (3) is irrelevant. (4) explains perfectly well why we shouldn't be surprised at (2), this being the WAP, which is banal to the point of triviality as I say.

    All this anthropic stuff is also not physics, btw. It is just really bad philosophy.

    ReplyDelete
    Replies
    1. Rollo,

      Yes, it's because a lot of people have, like you, wrong ideas about the Anthropic Principle that I made this video. How about you watch it?

      Delete
    2. I read your piece several times. I don't see, as I said that the weak anthropic principle is more than the sensible but trivial point that we must 'preserve the phenomena'.

      The piece here seems to debunk fairly thoroughly the claim that Hoyle's prediction was specifically anthropic:

      https://www.jstor.org/stable/41134335

      Delete
    3. Rollo,

      The Anthropic Priniciple is an observational constraint on the laws of nature. It is not any more trivial than any other observational constraint.

      I am familiar with Kragh's writing. I have referred to it here and also in my book. It's missing the point though. It doesn't matter at all what Hoyle's personal motivation was to see that the reasoning is sound.

      Delete
    4. Hi Sabine

      To be honest I don't think we disagree on the substance, but I do not think that the observational constraint here is worthy of being termed an independent principle.

      Compare, the tin principle: there is tin in the universe, therefore any theory of the universe must be compatible with the existence of tin. Repeat for any whatever phenomenon takes your fancy.

      It's perfectly valid, and as you say it is an observational constraint, but it seems a superfluous dignity to term it a principle.

      Delete
    5. Sabine Hossenfelder 6:26 AM, December 08, 2019

      "It doesn't matter at all what Hoyle's personal motivation was to see that the reasoning is sound."

      But the reasoning isn't sound.
      Whether life requires the C12 resonance *is not known*. It's pure speculation.
      That the C12 resonance produced a lot of carbon is known.

      No scientific facts have ever been found or ever will be found based on any version of AP because its constraints are not actually known.

      Delete
    6. Steven,

      Steven,

      As I said, physicists don't usually draw on the existence of human life, but preconditions for life.

      Delete
    7. Rollo,

      The Anthropic Principle is special because it is based on the only observation you cannot not make.

      Delete
    8. Sabine Hossenfelder11:43 AM, December 08, 2019

      "As I said, physicists don't usually draw on the existence of human life, but preconditions for life."

      And as I said C12 resonance or the carbon produced from it is not known to be a precondition for life. That is simply speculation.

      Delete
    9. Steven,

      As I said, that is entirely irrelevant. The relevant fact is that an observation gives you constraints on the hypotheses that you can put forward. Of course you cannot actually derive a hypothesis from an observation.

      Delete
    10. Sabine Hossenfelder 12:08 PM, December 08, 2019

      " The relevant fact is that an observation gives you constraints on the hypotheses that you can put forward."

      Observation: Lots of carbon
      Hypothesis: C12 resonance

      The hypothesis is allowed by the constraints imposed by the observation and turned out to be true.

      Observation: Life
      Hypothesis: No C12 resonance, much less carbon

      We do not know if this hypothesis is allowed by the constraints imposed by the observation, because we do not know the preconditions for life.

      Delete
    11. The only life we know is carbon based. Does this mean that life must be carbon based? No. Does it mean that carbon is a precondition for the life we know exists? Yes.

      Delete
    12. Sabine Hossenfelder12:55 PM, December 08, 2019
      "Does it mean that carbon is a precondition for the life we know exists? Yes. "

      Does all carbon come from the triple alpha process? No.
      Is the amount of carbon implying the C12 resonance a precondition for life? Don't know.
      Does the observation of lots of carbon allow the hypothesis of the C12 resonance? Yes.
      Does the observation of life allow the hypothesis of much less carbon than observed? Don't know.

      So the C12 resonance is an allowable hypothesis based on the amount of carbon in the universe, not preconditions for life. Because preconditions for life are not precisely known.

      Delete
    13. I will come back to see your reply in a couple of days.

      Delete
    14. Biology as we know it is carbon based. Is is possible there are other physical or chemical formats for something similar to life? Maybe.

      Consider the Earth and some of the planets such as Venus, Jupiter and Saturn. There is a constantly evolving electric potential between the upper atmosphere and the ground, or with a gas giant maybe deeper gas layers beneath. This has the effect of generating an 8Hz EM wave that circulates around being trapped by the ionosphere in a resonance cavity of sorts. It is also constantly changing its multipolar moment. Then when a dielectric breakdown happens with lightning this is analogous to the flip of a bit. So are planets sort of stochastic computational systems? Is this comparable enough to the nervous system to say there might be something similar to consciousness? On these I do not know, and asking a planet this question would prove difficult. This sort of system can occur without carbon.

      However, the WAP pertains to biology as taught in a biology department. Carbon is clearly a necessary precursor for biology.

      Delete
    15. Not entirely agreed. Carbon-based life may well be bound for self-destruction and its existence may just be an anecdotal accident in the history of universe. In fact, carbon abundance may be as much a precondition for the life we know exists as a precondition for extinction.

      Delete
    16. Steven,

      I already told you why your reasoning is wrong. No one says that it is possible to derive a hypothesis from an observational constraint.

      Delete
    17. Life is not eternal. Eventually the sun will exhaust it fusion energy stores and in around a trillion years stars in general will die out, except for the smallest dwarf stars. Biology will end and the universe will probably expand and continue for a very long time after. That does not preclude the fact that life exists now and that carbon is a necessary precursor for it.

      Delete
    18. Sabine Hossenfelder1:12 AM, December 09, 2019

      "No one says that it is possible to derive a hypothesis from an observational constraint. "

      You say in your post:
      "An observation gives rise to a hypothesis which makes a prediction that is confirmed by another observation."

      You are claiming that the C12 resonance is an anthropic fact. Historically it wasn't - Hoyle was motivated by the abundance of carbon, not the existence of life.
      Can it be considered an anthropic fact after the fact of the discovery? i.e. Can you prove that the abundance of carbon was necessary for life? No, not to the standards of empirical science. The triple alpha process is not the only source of carbon.

      So, yes, the Anthropic Principle is scientific, but it's useless - there are no examples of its use in science. The example you give is incorrect.

      Delete
    19. Lawrence Crowell 2:59 PM, December 08, 2019

      "Biology as we know it is carbon based."
      And not all the carbon on Earth came from the triple alpha process, so the C12 resonance is not necessarily an Anthropic fact. No other examples of significant scientific facts gleaned from the Anthropic Principle are being put forward, so we can conclude it's useless so far. And no surprise there.

      "this is analogous to the flip of a bit. So are planets sort of stochastic computational systems??"
      I reckon if you look around you could probably find a lot of things that are analogous to the flip of a bit. These are physical and chemical processes you are talking about. If a computation can be abstracted out of it I doubt it would be computing anything useful.

      "Is this comparable enough to the nervous system to say there might be something similar to consciousness? "
      Brains are the only objects known to exhibit consciousness - (subjective) empirical fact. Presumably consciousness arose due to the brain's need to observe itself to make sense of all the incoming sensory data so it could survive. I don't think the same biological imperatives and complexity exist in your planetary system. You are seeing the face of Jesus in a piece of toast.

      Delete
    20. Lawrence Crowell 5:32 AM, December 09, 2019

      "life exists now and that carbon is a necessary precursor for it."
      Sufficient. It's not known to be necessary.

      Delete
    21. RV3:46 PM, December 08, 2019

      "In fact, carbon abundance may be as much a precondition for the life we know exists"
      Is it? How do you know that?

      Delete
    22. Steven,

      I don't know what you mean by "anthropic fact". I have already told you several times that it is not possible (ever) to prove that a hypothesis must be correct, so your criticism is based on your misunderstanding how science works in general. This exchange is wasting my time and I have no interest in continuing it.

      Delete
    23. Sabine Hossenfelder12:50 AM, December 10, 2019
      "so your criticism is based on your misunderstanding how science works in general. "

      Very possibly, but these are your words:

      "An observation gives rise to a hypothesis which makes a prediction that is confirmed by another observation."

      But it was the observation of an abundance of carbon that gave rise to the C12 resonance hypothesis, not the observation of life.

      Again your words:
      "Fred Hoyle’s prediction that a certain isotope of the chemical element carbon must have a resonance because, without that, life as we know it would not be possible. "

      I don't think it is known for sure that life as we know it would be impossible without the C12 resonance. It's not the only source of carbon.

      Delete
    24. Sabine Hossenfelder 12:50 AM, December 10, 2019
      Lawrence Crowell 2:59 PM, December 08, 2019

      My obvious point is made in some physics paper below. Do you now agree, Dr H. and Lawrence, that we don't know even post-factum that the C12 resonance can be thought of as Anthropically predicted/suggested?
      (Ignore the paper's "fine-tuning" in the title, Dr H., the comment is the point.)

      "Stellar Helium Burning in Other Universes:A Solution to the Triple Alpha Fine-Tuning Problem"
      Fred C. Adams, and Evan Grohs
      "We note that some carbon can be produced without the triple alpha resonance, but the abundance would be much lower than that of our universe; since we do not know the minimum carbon abundance that is necessary for life, it is not known if such low carbon universes would be habitable. "

      Delete
    25. Sabine Hossenfelder 12:50 AM, December 10, 2019
      Lawrence Crowell 2:59 PM, December 08, 2019

      You don't say whether or not you agree with this obviously true statement of Fred C. Adams, and Evan Grohs:

      " since we do not know the minimum carbon abundance that is necessary for life, it is not known if such low carbon universes would be habitable."

      The point being that the Anthropic Principle has never shown itself to be useful for Physics.

      Delete
    26. Sabine Hossenfelder 12:50 AM, December 10, 2019
      Lawrence Crowell 2:59 PM, December 08, 2019

      Agree? Yes or No? If you don't answer (the Helbigian strategy) it suggests you cannot refute the statement and can demonstrate no useful applications of the Anthropic Principle.

      " since we do not know the minimum carbon abundance that is necessary for life, it is not known if such low carbon universes would be habitable."

      Delete
    27. Without 3He --> C there would be no life. That appears pretty evident; if the universe contained no or very little carbon biology would be far less likely. The converse is with 3He --> life, which is not the same. the occurrence of carbon is not a logical condition for life. I agree there could have been no life, and as yet we do not know all the precursor requirements for life. It could just be a huge fluke. The point of the WAP though is "life exists therefore 3He --> C" which is just the modus tolens of the first proposition.

      Delete
    28. @Lawrence.
      “Life is not eternal. Eventually the sun will exhaust it fusion energy stores and in around a trillion years stars in general will die out, except for the smallest dwarf stars. Biology will end and the universe will probably expand and continue for a very long time after. That does not preclude the fact that life exists now and that carbon is a necessary precursor for it.”
      Sorry, Lawrence, for sloppily skipping quotations. My comment was not in response to your previous comment on top of mine, but to Sabine’s earlier statement that carbon is a precondition for the life we know exists (which I very much subscribe). Anyway, I am aware that life is not eternal and the Sun will die out, but this is not an accident in the history of the universe, because the Sun will last for long enough to deserve a place in universal history. However, human life, or carbon-based life, which led/leads to human life (according to the WAP it is just a precondition, but according to our records it is the only known outcome of carbon abundance), may also unavoidably lead to self-extinction, so carbon-based life may not deserve such a prominent place in the history of the universe. That’s my whole point. And basing physical theories on the WAP is IMHO not a very solid assumption to start with.
      Best

      Delete
    29. Lawrence Crowell 11:24 AM, December 13, 2019

      "if the universe contained ... very little carbon biology would be far less likely."

      Maybe. But that doesn't mean the C12 resonance is anthropic. It is not known if carbon-based life would be possible in a universe with just the carbon from non-triple alpha processes.
      It is not known how much carbon-based life there is in the universe. There may be masses of it, so that less carbon might just mean less life not no life.

      The C12 resonance might be anthropic, that's the most that can be said. And so the Anthropic Principle is not known to be useful for science.

      ( "life exists therefore 3He --> C" which is just the modus tolens of the first proposition."
      It's the contrapositive of the first proposition, so logically equivalent to it, therefore unknown to be true.)

      Delete
  27. There are only a few factors that control the constancy of the laws of nature. These factors involve the energy content of the vacuum and how that vacuum behaves.

    Calculations show that if the mass of the Higgs boson were just a few times heavier or lighter and everything else stayed the same, protons could no longer assemble into atoms, and there would be no complex structures—no stars or living beings. So, what if our universe really is as accidentally fine-tuned as a pencil balanced on its tip, right on the brink of a phase transition, singled out as our cosmic address from an inconceivably vast array of bubble universes inside an eternally frothing “multiverse” sea where the laws that prevail in those universes are different and simply because life requires such an outrageous accident to exist in our universe? The vacuum should be 120 orders of magnitude more energetic than it is. Why has the energy of the vacuum stabilized at its current value just above its zero point?

    But the Higgs field is set exactly on its tipping point, just like if water was set at its triple point.

    If the strength of the Higgs field is increased or decreased by the slightest amount then there would be a change of state that would occur in the vacuum that profoundly would affect the nature and behavior of our universe. This fined tuned nature of the vacuum has existed for almost all of the time that the universe has been in existence. This nature of the vacuum on its tipping point has never varied and has stayed rigidly constant even as the universe has expanded over it billions of years of existence.

    Can the nature of the vacuum be changed in any way to form bubble universes that differ from our own by processes that we can control so that we can study how these bubble universes behave and the new laws of nature that they manifest?

    Discovering the ways and means of this control of the vacuum lies the answers to why life and our universe is the way that it is.


    ReplyDelete
  28. "If you believe in the multiverse, then the anthropic principle can be reformulated to say that the probability we find ourselves in a universe that is not hospitable to life is zero."

    Dr. Hossenfelder, can you comment on Oxford philosopher Nick Bostrom’s 2002 book Anthropic Bias: Observation Selection Effects in Science and Philosophy, wherein he specifically denied that conclusion? He wrote: (p. 55)

    “It isn’t true that we couldn’t have observed a universe that wasn’t fine-tuned for life. For even ‘uninhabitable’ universes can contain the odd, spontaneously materialized ‘freak observer’, and if they are big enough or if there are sufficiently many such universes, then it is indeed highly likely that they contain infinitely many freak observers making all possible human observations. It is even logically consistent with all our evidence that we are such freak observers.”

    Bostrom’s reasoning is essentially a Boltzmann-Brain-type argument: (pp. 52-53)

    “Consider a random phenomenon, for example Hawking radiation. When black holes evaporate, they do so in a random manner such that for any given physical object there is a finite (although, typically, astronomically small) probability that it will be emitted by any given black hole in a given time interval. Such things as boots, computers, or ecosystems have some finite probability of popping out from a black hole. The same holds true, of course, for human bodies, or human brains in particular states. Assuming that mental states supervene on brain states, there is thus a finite probability that a black hole will produce a brain in a state of making any given observation. Some of the observations made by such brains will be illusory, and some will be veridical. For example, some brains produced by black holes will have the illusory of [sic] experience of reading a measurement device that does not exist.”

    So, according to this line of thought, an infinite multiverse would undercut our ability to have confidence in our measurements, which in turn would undercut our ability to do physics, which would negate our ability to infer the actual existence of a multiverse. This seems to be a difficult, self-referential problem.

    ReplyDelete
    Replies
    1. Mike,

      I did not say the universe is fine-tuned for life. I did not even use the word fine-tuning. If Bostrom wants to argue that humans can exist in a universe in which they can't exist, he has a linguistic problem. Also, "freak observers" aren't a thing.

      Delete
  29. THE INEFFICIENCY OF ANTHROPISM

    Quick! What percentage of matter in the entire universe is devoted to the composition of intelligent beings capable of contemplating said universe?

    No, I don't know either… but I think you will agree with me that it's so blinking low that it would be difficult to write all the leading zeros, yes?

    Also, if I asked the same question in terms of "space occupied", wow, however bad the earlier answer was, this answer will be literally astronomically smaller.

    Quick! How many elements are absolutely crucial to the existence of life as we know it?

    Well, that question at least is not insane. A remarkably large number of elements, in some cases really odd ducks (molybdenum? really?) are involved with life as we know it, but only a more common handful — carbon, nitrogen, oxygen, and hydrogen — make up the majority of mass of most organisms. And of that set, carbon plays a very unique role as the only limits-free "tinker toy" element, the only one that allows huge, diverse, and strong chains to form. Even nitrogen and benefits from carbon on that point, since its proximity to carbon allows it to form similar but weaker, more composable bonds (think "proteins").

    (Boron, which similarly benefits from it next door neighbor status to carbon, is not used structurally by life. That is a bit quirky, definitely interesting, and mostly likely due simply to its tendency to turn into borate in water. But who knows, perhaps somewhere in the universe there is non-water life based on "borino acids" instead of amino acids, using boron analogously to nitrogen to create breakable pieces.)

    Chemical tangents aside, the point is this: Carbon is a small percentage of a larger number, the number of elements, and once again seems critical to at least any obvious way to build sentient beings via the chemistry route.

    Quick! How much of the universe is amenable to sentient chemical life?

    Based on what we know, again, not much at all. The surface of earth in our solar systems is about it, and that's not much by mass, not much at all. If a cosmic cleaner came by, we would not be much more than a bit of grease on the surface of one of the tiniest bearings in a gigantic machine.

    Quick! How much of the universe is even matter in the first place?

    Well, of course we know the answer to that one, sort of: Not nearly as much as we used to think. The idea that matter is not much more than froth on waves seems to capture the idea pretty well, in fact.

    SO WHY IS ANTHROPISM SO INEFFICIENT?

    My point of course is simply this: If anthropism is such a powerful organizing principle of the universe, then why is it so incredibly inefficiently?

    Wouldn't you expect a universe designed for life to be, you know, chock full of it at every level of design, using most of its mass, creating so much of it that almost all of its mass, or space, or elements, or other resources are devoted to it?

    But that is not what we see, and that is important.

    We just don't know why.

    ReplyDelete
    Replies
    1. "Wouldn't you expect a universe designed for life to be, you know, chock full of it at every level of design"

      Let me just check with the other universes. Oh, there's only this one. I don't see what this kind of speculation (AP, fine-tuning) has to do with physics. Give these questions to the "philosophers" - they are happy to study pointless questions for thousands of years and not produce a single fact.

      Delete
    2. We give ourselves a lot of value, and if we saw it in a broader way ?; the universe is made to allow the existence of many things, even when it continues in its evolution and other conditions exist, other things will exist; Anyway, we sneak into the party

      Delete

    3. Evans, do you think Einstein would have developed his theories without having the right philosophical position?

      Delete
    4. Luis 5:51 PM, December 10, 2019

      What was this crucial philosophical position?

      Delete
    5. That is to say, that according to you, in Einstein's reasoning he began with mathematics, that led him to new physical concepts; Or were the facts? How did he get to these new physical concepts? ; considering that its profound transformation was about the general frameworks we use to understand physical reality; Do you really think that his philosophical position played no role?.

      Delete
    6. Luis7:22 PM, December 11, 2019

      I never said he began with Mathematics. Of course, he didn't. He began with unanswered questions in physics.

      What is this claimed "philosophical position" and what "role" did it play in Einstein's work? I've no idea what you are on about.

      Delete
    7. Luis7:22 PM, December 11, 2019

      What is this crucial philosophical position of Einstein's? I can't see that you've answered.....

      Delete
  30. Helge Kragh has written an article of some interest: "An anthropic myth: Fred Hoyle’s carbon-12 resonance level" (Nov 2012, Archive For History Of Exact Sciences):"The case of Fred Hoyle’s prediction of a resonance state in carbon-12, unknown in 1953 when it was predicted, is often mentioned as an example of anthropic prediction. However, an investigation of the historical circumstances of the prediction and its subsequent experimental confirmation shows that Hoyle and his contemporaries did not associate the level in the carbon nucleus with life. Only in the 1980's, after the emergence of the anthropic principle, did it become common to see Hoyle’s prediction as anthropically significant. At about the same time mythical accounts of the prediction and its history began to abound. Not only has the anthropic myth no basis in historical fact, it is also doubtful if the excited levels in carbon-12 and other atomic nuclei can be used as an argument for the predictive power of the anthropic principle." There is another 36-page paper by Kragh (2013): "When is a prediction anthropic ?" (pdf from UPitt.edu). A discussion regards Hoyle is found in Barrow and Tipler where they write: " Hoyle realized that the remarkable chain of coincidences...were necessary, and remarkably fine-tuned, conditions for our own existence and indeed the existence of any Carbon-based life in the Universe." (page 253).

    ReplyDelete
  31. The weak anthropic principle is a theorem. It says given a space of possibilities, if there exists a patch no matter how small that supports complex structure we must find ourselves there and that must be what we observe. Therefore, observing fine tuning is unremarkable and not evidence that the whole space is built that way or that we're exceptional.

    The strong anthropic principle is a postulate. It says the evolution of complex structure at least somewhere must be a robust phenomenon. The how is left open. The correct theory of everything must converge to evolve complex structures, or must contain something like many worlds or mathematical universe to explore the space. Or in some other way we haven't thought of the evolution of structure at least somewhere must be guaranteed.

    The strong form can be investigated, at least in theory. For me at least, the question of how robust is the formation of complex structures in the space of all mathematical formulations is the most interesting problem in physics. Or in the whole search for knowledge.

    ReplyDelete
    Replies
    1. We know the Second law of thermodynamics. This law postulates the "degredation" of matter and energy.

      But we know no law which postulates the well observed rising of structures and complexity - so our knowledge of nature is blatant wrong, yet.

      Delete
    2. Arrgghh!!! This is simply wrong. The objection to evolution and development of structures within the context of thermodynamics is wrong and the answer is well known. This objection was answered long ago. I am not going to go into it! It is up to you to look this up.

      Delete
    3. We know that evolution is extremely robust once it starts. The question is does the fundamental physics allow enough non-linearity and stability for complexity to evolve? String theory says no, most solutions diverge into simple states hence there must be a mechanism like the multiverse to explore the state space. I've no opinion on string theory but my hunch is mathematical structures are able to sustain complexity more universally than we imagine. We just don't know how to calculate it when it's different than the path that led to us.

      If I was to start a PhD it would be to explore the space of mathematical formalisms and run simulations to check what proportion of math space is able to form complex structures. If possible, to indicate what characteristics of the formalism are needed for evolution to happen. We think that non-linearity and stability are part of the picture, is that all? Is there a minimum measure of non-linearity or degrees of freedom? I do think it's the most interesting scientific question one can pursue.

      Delete
  32. Max Planck (1909): "each great physical idea means a further advance toward the emancipation from anthropomorphic ideas and "the system of physics is still suffering from a strong dose of anthropomorphism." (pages 7 and 20, Lectures on Theoretical Physics).

    ReplyDelete
  33. Of course :) the Anthropic Principle is not surprising if the answer is "Yes" to

    "Is the Universe Conscious?"
    NBC News | Science
    https://www.nbcnews.com/mach/science/universe-conscious-ncna772956

    "Can Panpsychism Become an Observational Science?"
    Gregory L. Matloff
    Physics Dept., New York City College of Technology, CUNY
    Journal of Consciousness Exploration & Research
    https://jcer.com/index.php/jcj/article/view/579 (open access)

    "In this model, a universal field of proto-consciousness is congruent with the fluctuations in the universal vacuum."

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    Replies
    1. How does this theory avoid predicting that we should be Boltzmann brains, i.e. that the information we're aware of should be maximally random such that it's just consistent with being us?

      Delete
    2. Saibal Mitra:
      I see no problem with each of us needing only infinite instances of static Boltzmann brains expressed in an infinite, high-dimension field of static. (See my post from Dec. 8 @ 3:30)

      Delete
  34. I think that everything cannot be reduced to infinite probabilities, the universe may be composed of two or three parameters and have very few options of being different. Suppose I have a number of magnets, in the amount of 1 by 10 raised to 90; Can someone calculate what configuration the final object will have after all the magnets interact with each other ?; In addition to the magnetic field, I add the fact that each magnet can stretch and shrink

    ReplyDelete
  35. A DESIGN-COST LOOK AT ANTHROPISM

    The periodic table is relevant to anthropism not because it "requires" life (it does not), but because it provides the chemical equivalent of a powerful and highly generalized programming language. The full breadth of this elemental language is largely unfathomable at the table level, but it's there. Its combinatorial potential is particularly profound around carbon, the source of organic chemistry.

    One way to assess both the complexity and specificity of a language is to treat it as a design problem. Thus if asked to recreate the chemical elements in software, a programmer's first reflex would be to create a literal table with modifying rules per row and column, much as Mendeleev did. The resulting code would not be compact, but neither would it be terribly verbose. It would be akin to the current state of the Standard Model of particle physics.

    UPPING THE ANTE

    But now let's apply what's been learned since Mendeleev.

    If you look at a chart of isotopes you will see that the list of stable isotopes that forms the periodic table is just a strikingly narrow peninsula of stability jutting out into a sea of instability (with gaps at technetium and promethium, shallow wading pools at thorium and uranium, and an atomically thin layer of water over bismuth.) The new and far more more difficult task is to create all of these stable and unstable isotopes, using both electron and nucleon chemistry.

    THE PROTON PROGRAMMING PARADOX

    Now let's up the ante one more time, this time enormously, by adding a truly insane design constraint.

    The programmer must now create the table-like geometry of the peninsula by using only simple sums of three parts, the proton, neutron, and electron. Even worse, these parts are also quite simple, with only a small number of properties such as mass, volume, spin, and various types of charge. The programmer can tweak these properties as desired, but in the end must ensure that simple sums of them will recreate the table-compatible peninsula.

    This is the point at which all sane programmers quit.

    While programmers also use simple parts — bits — they are normally permitted to configure those bits into strings of indefinite length and complexity. Asking them instead to make the periodic table emerge from simple sums of low-complexity parts is something else entirely.

    Successful examples of such emergent programs are very rare in technology literature. There was for example a 1996 paper by Adrian Thompson that described evolution of an unclocked tone discriminator using only 40 FPGA devices (e.g. transistors). Alas, evolvable hardware has not made much progress since then, and even the details of how Thompson's device worked are still not well understood.

    ANTHROPISM AS CASCADING COMBINATORIAL EMERGENCE

    If you disdain anthropism as meaningless philosophy, perhaps a more useful view is this: In a complex universe that in general does not seem to favor life or intelligence (see my earlier post), there nonetheless exists a cascading sequence of emergent phenomena that locally create increasingly powerful "languages" or "part sets" that combine in indefinitely complex ways. Once such a part set emerges, the very breadth of its combinatorial expansion creates an opportunity a new, more powerful, but also more localized combinatorial part set to emerge. Thus particles combine to create carbon and the periodic table. The combinatorics of that table — chemistry — does not "require" life, but in protected environments it does enable the formation of yet another combinatorial set, amino acids, which are the language of proteins. And on it goes.

    The real mystery of anthropism thus is this: Why does this cascade of combinatorial languages seem to extend all the way down to the nature of physics, and perhaps of mathematics itself?

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  36. Terry Bollinger11:44 AM, December 08, 2019
    "Why does this cascade of combinatorial languages seem to extend all the way down to the nature of physics, and perhaps of mathematics itself?"

    Chronologically physics built up into chemistry built up into biology. That's why. What's the mystery here?

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  37. I have never understood this anthropic reasoning which I consider reverse reduction-ism. So suppose the dinosaurs wouldn't have become extinct because of the meteor and because we would not be here because of their dominance. Then I have a question for you which I consider as a 'duality formalism' for the anthropic principle : do you think nature would consider itself as being Quantum Mechanical if humans wouldn't be around. I leave this for you as a thought exercise to ponder about.

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    1. To consider itself anything, nature would have to be conscious, and it is not even known to be self-conscious. But nature IS most probably quantum mechanical with or without us. I think the SAP, even if valid, is naïve at best, because it can help very little toward the progress of science. Those physical laws that agree with all present and future terrestrial or extraterrestrial observations are valid beyond doubt and irrespective of human existence. And it is my uninformed opinion that those laws must only involve basic preconditions, like the cosmological principle or some similar, anthropic-free assumption. But congrats to the first one who extracts valuable information from the so-called anthropic principle.

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    2. The essence of my reply is that you can formulate any sort of law without humans being present, as seemingly valid in nature. As a stressed example even in mathematical nonsense of by aliens. The a-principle only has a narrow boundary induced by humans when they are confronted with their own mind.

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    3. "The essence of my reply is that you can formulate any sort of law without humans being present, as seemingly valid in nature."

      Leaving aside metaphysical considerations on who would do that and how if we were not here (much in the same way probably), 100% agreed.

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  38. The article itself seems more like a provocative question; how difficult it is to get rid of all subjectivity to try to understand reality !; almost what can be done; But much is lost along the way. Excellent article.

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  39. The Anthropic Principle is just another banana taped to a wall.

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  40. Brandon Carter's "Large number coincidences and the anthropic principle in cosmology" can be read in its entirety online. I like what he writes: " It is, of course, always philosophically possible to promote a prediction based on the strong anthropic principle to the status of an explanation by thinking in terms of a world-ensemble...an ensemble of Universes characterized by all conceivable combinations of initial conditions and fundamental constants. The existence of any organism describable as an observer will only be possible for certain restricted combinations of the parameters, which distinguish within the world-ensemble an exceptional cognizable set." (1973, page 296).
    The entire article is lucid and well-worth reading.

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  41. Steven Evans, the mystery in the case of physics is that we are missing the huge expanse of non-productive variations. We just see one physics, the same one that produces the periodic table, and it appears to be universal. All the other preconditions for life are by contrast extremely rare percentage-wise.

    I can even phrase that as a very vague prediction: If anthropism really is just a cascading series of increasingly localized and unlikely combinatorial "languages", then physics as we know it cannot be quite as invariant as it seems. The particular physics of our universe would instead need to the result of a some particular and universally shared combination of simpler parts - and that is not the same thing as invoking a multiverse.

    Classical physics would represent the most "locked down" extreme of this consensus, while quantum behavior would be a peek (still limited by our intrusion as classical observers) at the more flexible underlying set of rules. Feynman QED for example requires exploration of multiple values for c.

    The experimental implication is that different dense combinations of local agreements - solid state physics - could actually create demonstrably different local physics rules from those governing the universe at large.

    Do possible candidates already exist?

    Sure: High-temperature (e.g. cuprate) superconductors possibly could be bending some rules locally. It would certainly provide a reason why they've been so hard to explain.

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    1. Terry Bollinger 3:10 PM, December 08, 2019

      "the mystery in the case of physics is that we are missing the huge expanse of non-productive variations. "
      How do we know the non-productive variations are physically possible? You have abstracted away the natural science, are left with combinatorics and can now combine anything and everything. It's not necessarily a physically possible model though, is it?

      "We just see one physics, the same one that produces the periodic table, and it appears to be universal. All the other preconditions for life are by contrast extremely rare percentage-wise."

      There was a little blob of quarks, it expanded, now it's everywhere. I don't think the preconditions for life are known. It's not known how common it is in the universe, etc.

      "then physics as we know it cannot be quite as invariant as it seems. "
      Why does this follow? You can make more and more complex structures out of the building blocks of physics. It's not known why but it's described in detail. Why does that imply the building blocks could be different in nature?

      "The particular physics of our universe would instead need to the result of a some particular and universally shared combination of simpler parts "
      But this is exactly what physicists have been doing - reducing nature into smaller and smaller building blocks. And what they have produced is empirically verified.

      "Classical physics.. "locked down" extreme .. quantum behavior .. more flexible underlying set of rules."
      Quantum behaviour has been observed to be the fundamental physical nature and classical physics is what it looks like en masse. I don't see why that implies other possibilities for physics.

      "Feynman QED for example requires exploration of multiple values for c."
      But isn't that just a handy technique rather than being representative of reality? I mean you're talking about something that is happening in a model not reality.

      "could actually create demonstrably different local physics rules from those governing the universe at large."
      Mmmmm, really? What quarks and electrons behaving differently to how they are prescribed to? I find this difficult to believe without empirical evidence.

      " High-temperature (e.g. cuprate) superconductors possibly could be bending some rules locally."
      And give me a shout when that becomes definitely.

      Without some empirically verified output from these ideas, I don't buy them. Maybe it's a brilliant idea though and I just don't get it. A distinct possibility.



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  42. The only thing I know for certain is "I" am aware.
    That means "something" exists. Something implies "1".
    Even if the ultimate reality is just a single, zero-dimensional point, isn't that equivalent to a realm of infinite curvature, with the pure abstraction of "1" relating with itself in infinite ways across infinite dimensions?
    Those relations are described by mathematics. Within mathematics, there is at least one subset of relationships that leads to a conscious observer ... the one in which I'm communicating with you right now.
    It seems clear to me, given the fine-grained nature of the universe I perceive, that there should be a vast number of *almost* identical universal conditions where my consciousness can endure. Think of these related states as bubbles of useful complexity in an infinite sea of static. Each bubble represents a "moment" in my consciousness. The indeterminacy and fuzziness of the rules that physics seems to obey arises from the fact that my awareness is little affected by residing in either of two universes (to use a trivial example) where the only difference is a single electron in a state of spin up vs. spin down.
    The only element that seems absolutely essential for consciousness is the passage of time ... a dimension with a preferred direction that allows memory and anticipation. This leads to perception of a "branching" universe, with an isolated consciousness on every path.
    Since there are always bubbles of useful complexity that correspond to an additional moment of my awareness, I can expect to be conscious eternally. This allows my hypothesis to be tested. If my consciousness endures for a period that represents a six-sigma violation of pre-existing biological expectations, my immortality will be as certain as the existence of the Higgs boson.

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  43. Sabine Hossenfelder wrote:
    “...physicists don't usually draw on the existence of human life, but preconditions for life.”

    Hi Sabine,

    In regards to those “preconditions for life,” in considering the alleged lifeless status of the universe during the billions of years prior to the emergence of mind and consciousness,...

    ...have you never wondered how it was possible that chaotically dispersed fields of unconscious particles of matter could somehow “know” how to adjust and combine their waveform attributes in such a way that would not only produce a majestic stage upon which consciousness could effloresce from the fabric of the stage itself...

    ...but also equip that stage with an amazing array of features that are so wonderfully “appealing” to the five senses of consciousness?

    In other words, the question is: how did mindless algorithmic processes that seem to operate in a purely “noumenal” (phenomenonless) context...

    (without any way of determining what the universe’s three-dimensional structures would actually look like, feel like, sound like, smell like, or taste like to consciousness)

    ...again, how did these primordial quantum processes blindly configure themselves in such a way so that in the presence of some future consciousness, a three-dimensional setting consisting of fragrant vines of blooming honeysuckle, and beautiful mountain streams, and a vast cornucopia of delicious foods, etc., etc., would suddenly emerge from the patterns of information?

    Furthermore, if it is even remotely possible that consciousness is somehow involved in the collapse of the wavefunction,...

    ...then a circular dilemma arises if one believes that consciousness is an “emergent” property of an already ordered, 3-D state of matter when, in fact, there can be no 3-D state of matter without the presence of consciousness.

    Sabine, I have nothing but the greatest of respect for your prowess as a theoretical physicist (and a darn good musician to boot), and I get it that this is your personal blog and that you only have so much time and energy (and patience) to devote to these discussions.

    However, along with your hard credentials as a working physicist, if you also fancy yourself as a “philosopher” of science...

    ...then you should be more open to addressing the problem of the absurdity in thinking that the utterly blind and mindless (ham-handed) processes of “gravity and thermodynamics” could somehow cause random particles of matter to magically coalesce into a context of order that defies our comprehension.

    Have you no thoughts on this issue?

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    1. Keith,

      Part of the answer certainly is a rather trivial application of the weak anthropic principle: there are lots of planets that do not have "fragrant vines of blooming honeysuckle, and beautiful mountain streams, and a vast cornucopia of delicious foods..."

      But we could not have evolved on most of those planets.

      As far as scientists know, there is not a deep dark mystery as to how stars form, planets are created, life evolves, etc. Of course, there are still "puzzles" we have not solved in all of those areas, but we have no reason to think that they cannot be solved by the laws of physics as we now understand them.

      Consciousness? Well, I am pretty sure I am conscious, but sometimes I have my doubts about some of the rest of you!

      Dave

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    2. Much of physics is Gaussian or with Markovian statistics. This produces white noise, such as the annoying sound of a radio not tuned to a station. Complex processes tend to be more pink noise, such as the more pleasant sound of a water fall. It is not clear how Markovian systems compose subMarkovian systems. However, there is some means by which selection occurs. This means certain structures that might emerge randomly are preferentially selected or are more durable against random noise.

      Biological evolution runs into a bit of its "singularity" when it comes to origins. At this stage there is some sort of "molecular selection" process. This is an area of considerable ignorance and some researchers are pursuing this. It is tough to know if we can ever find signature of pre-biotic chemistry and selection. It has been largely erased on Earth. It might exist on Mars, though it will take a lot of effort to find it.

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    3. "...have you never wondered how it was possible that ... matter could somehow “know” how to adjust and combine their waveform attributes in such a way that [magnificent creatures such as Donald Trump could exist] ..."

      The answer is that evolution does not know what is going to happen, just as you were not born knowing how to ride a bicycle. Successes are found by trial and error. There is no magic involved. Edison, with an 8th-grade education, tried roughly 1000 ways to make a light bulb filament. The first practical thing he found was carbon soot embedded in coarse thread. The best thing he ever found was bamboo fiber. Einstein tried several things as equations for General Relativity (see his Zurich notebook) before finding one that worked, and there were several more trials and errors as GR was develeloped. The basic algorithm, the one ring that rules them all, is the evolutionary algorithm, which in turns depends on the fact that if a workable solution exists, given enough trials a random search will find it. Once a workable solution is found, it can be improved by further trial and error.

      The history of science and engineering is one long illustration of this principle. I don't believe there is anyone who has not experienced this personally. For me, trial and error wins vs. magic by both Occam's Razor and Mario's Sharp Rock.

      (Mario's Sharp Rock: of competing hypotheses, the one that is the most humbling is most apt to be true.)

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    4. PhysicistDave wrote:
      “Part of the answer certainly is a rather trivial application of the weak anthropic principle: there are lots of planets that do not have "fragrant vines of blooming honeysuckle, and beautiful mountain streams, and a vast cornucopia of delicious foods..."

      But we could not have evolved on most of those planets.”
      ----------------
      Hi Dave,

      Well, we didn’t need to evolve on those planets, now did we? For this one did the job remarkably well.

      As far as I’m concerned, planets that are incapable of supporting life are simply there as future material resources for life to draw upon once it (life) has evolved enough to conquer space (be it us or others throughout the universe).

      In other words, the vast number of uninhabitable planets should not be viewed as a reason why the universe seems so inhospitable to life, but more of a demonstration of the inherent teleological workings of the universe that have yet to come into play.

      PhysicistDave wrote:
      “As far as scientists know, there is not a deep dark mystery as to how stars form, planets are created, life evolves, etc. Of course, there are still "puzzles" we have not solved in all of those areas, but we have no reason to think that they cannot be solved by the laws of physics as we now understand them.”
      ----------------
      Sure, we can attempt to understand the processes by which the stars and planets are formed, however, that’s not the mystery.

      No, the real mystery is how anyone could believe that such an incalculable array of prerequisite conditions that are required for the manifestation of life could simply “fall into place” by sheer luck.

      For one thing,...

      (and to slightly paraphrase something I’ve stated elsewhere)

      ...if your mind isn’t blown by the unimaginable stability of the millisecond-by-millisecond precision with which this gigantic orb we are standing on - gently moves around the perfect source of light and energy (unerringly for billions of years), then something is amiss.

      We’re talking about the precise movement of a gargantuan sphere that not only spins vast oceans and bustling human metropolises, around and around - “topsy-turvy” - in a rotisserie cycle that only takes a mere 24-HOURS to complete,...

      ...but also whose position in space can be determined with astonishing accuracy – thousands of years in either direction of time.

      Yet it is presumed (taken for granted by materialists) that such steadfast axial/orbital precision...

      (something that had to be in place before the processes of evolution could even begin)

      ...is simply the result of chance and serendipity.

      Now if you just take that singular “miracle” of an unfathomably stable orb being powered by the perfect source of light and energy for billions of years,...

      ...and then combine it with the even greater miracle that “chance and serendipity” also managed to equip the orb with every possible ingredient necessary to awaken us into existence,...

      ...you will then have a clearer understanding of my position*.

      *(A position, btw, that when combined with $1.50 will get me a ride on the city bus. Ha!)

      PhysicistDave wrote:
      “Consciousness? Well, I am pretty sure I am conscious, but sometimes I have my doubts about some of the rest of you!”
      ----------------
      Be careful, Dave, because just as somnambulists are unaware of the fact that they are sleepwalking, likewise, it is difficult for any of us to self-determine the true level of our own consciousness.

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    5. Lawrence Crowell wrote:
      “Biological evolution runs into a bit of its "singularity" when it comes to origins. At this stage there is some sort of "molecular selection" process. This is an area of considerable ignorance and some researchers are pursuing this. It is tough to know if we can ever find signature of pre-biotic chemistry and selection. It has been largely erased on Earth. It might exist on Mars, though it will take a lot of effort to find it.”
      ----------------
      Hi Lawrence,

      You make some good points.

      However, the problem with your “molecular selection process” is that it is set within the context of an already established and functioning biosphere that is fully stocked (equipped) with every possible ingredient necessary for the “molecular selection process” to unfold.

      Now if you can stomach my speculative ramblings and rantings,...

      (and assuming that Sabine approves our postings in the order they are submitted)

      ...then please read what I said to PhysicistDave in my prior post.

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    6. I overlooked this. My statement about a molecular selection process refers to the pre-biotic chemistry that lead to biology. This is where biological evolution runs into some difficulty. There may have then been some form of screen or selection system for molecules that define life. As yet it is not known how RNA and DNA are synthesized in purely natural environments. How ribosomes emerged is an even bigger mystery.

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  44. I think the significance of the anthropic principle lies in our attitude to numerical coincidences in the constants of nature.

    If we believe that we have no conceivable basis by which to select a prior probability distribution for these constants, then there is no need for the anthropic principle. However, if you find these coincidences surprising and worth thinking about, then the anthropic principle can intervene if one can show that the universe would not be amenable to intelligent life if the constants had different values. At this point we would need to ask how the coincidences could come about if there were only one universe.

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  45. I'm going to be a bit of a party-pooper.

    The comments here are replete with the word "constant", and many refer - explicitly or implicitly - to values of parameters usually labeled "fundamental constants".

    The NIST site has lots of tables of these:
    https://physics.nist.gov/cuu/Constants/index.html

    Some are "constant" by virtue of having a defined value, such as c (speed of light in a vacuum). They are thus simply the means by which certain physical things are defined, in quantitative terms.

    The rest have values which are determined experimentally.

    For example, the Newtonian constant of gravitation (G) ... its numerical value is given as 6.674 30 x 10^-11 m^3 kg^-1 s^-2, and its "standard uncertainty" as 0.000 15 x 10^-11 m^3 kg^-1 s^-2. So its "true" value is somewhere between 6.674 15 and 6.674 45 (dropping all the x 10^-11 m^3 kg^-1 s^-2 parts). Or perhaps in an even wider range, depending on your view of what the PDF is. As far as we can tell, today, all universes in which G is in that range are possible.

    A more fundamental (ha!) consideration: some constants are defined the way they are because we think that Special Relativity (SR), say, rules in the universe we live in. And we have - to date - no consistent, objective, empirical evidence that it does not (the same is true for GR, despite the many comments by some, on other blogposts here).

    But perhaps, tomorrow, a new fundamental theory of physics will be shown to be a better fit to all relevant observational and experimental results within its domain, a theory in which some of the "fundamental constants" are no longer constant?

    These are very real wrinkles on all anthropic principles, I feel. Yet they are seldom even noted, much less discussed.

    Why is that?

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    1. In a thoughtful review article, Jean-Philippe Uzan writes: "We define the fundamental constants of a physical theory as any parameter that cannot be explained by this theory" and "therefore, these fundamental constants are contingent quantities that can only be measured. Such parameters have to be assumed constant in this theoretical framework..." and "indeed, when introducing new, more unified or more fundamental, theories the number of constants may change so that this list reflects both our knowledge of physics and, more important, our ignorance..." (2011 Living Reviews in Relativity, "Varying Constants, Gravitation and Cosmology").

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    2. Thanks Gary Alan! That's a great article, and we surely could have used some of what's in it to avoid the ambiguity (and much more) which is so obvious in so many of the comments here. In particular, the relationship between "constants" and the WAP.

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  46. A couple of comments touch on "infinite multiverses." However, "infinite reality" is good enough. There are no known boundaries to "Reality." Even if there was a BB, energy was required to "bang" - unless one posits a non-physical creator. Crunches and bangs could be infinite. Thus Occam's Razor tells me that infinite possibilities of combinations of whatever exists *must* eventually result *someplace-time* in a life form like ours. Forever is a long time. ;-)

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    1. I concur! It doesn't have be any more complex than infinite opportunities for expression of Boltzmann brains in a field of multidimensional static (see my post from Dec. 8 @ 3:30 pm.

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  47. It seems to me that we don't need a "multiverse" to explain why life exists on Earth. All we need is a "multiplanet", i.e. a vast number of planets with different conditions, and this is exactly what we've got. So, Goldilocks doesn't need a multiverse.

    Separately, if aliens arrived tomorrow, then we would know that interstellar travel is both possible and practicable. We could then go about discovering the science behind the alien technology. This would be an example of applying the weak anthropic principle, or should that be the weak alien principle.

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  48. another fascinating discussion. The weak anthropic principle is, to me, a useful boundary for speculation about the underlying constituents of physical existence. Given that collections of objects tend to self organize, when regularly perturbed, the existence of mathematically describable patterns is not surprising.
    However, that effect may it self be subject to the Anthropic Principle. Or life exists simply because enough dice rolled often enough results in us.

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  49. Bee; the anthropic principle; I think it has a very practical utility; we know that we exist, if someone comes up with a model of the universe very beautiful and very harmonious and mathematically impeccable; but it does not allow our existence; Then we can throw it away.

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  50. I think you have nailed the admittedly moderate value of the WAP and the mysticism of the SAP. When I read Barrow and Tippler “The Anthropic Cosmological Principle “ 30 years ago it made me think about answers to strange questions like “Why does the moon almost exactly cover the sun” giving rise to the wonder of occasional solar eclipses. I realized that it’s possible that a moon is necessary for the development of sentient life. It stabilizes the angular tilt, provides right size tides to speed the transition of life from seas to land, and even perhaps stimulate the observation snd recording of celestial phenomena. Since tidal friction causes the moon to move away and reduce its tidal impact there may even be a link between the time for a moon sized body starting very close to the earth and the time necessary to evolve multicellular then sentient life.
    Then I wondered if there was actually a mechanism for the SAP. It needs a few assumptions. Our universe is cyclic. Each cycle could have different constants candy you could tune the next universe by intervention in this one. A few billion years of diligent work by Von Neuman machines could make the adjustments necessary and ensure the “next “ universe is ideal for the evolution of life and its long term security.

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  51. Somebody said that life would not had been developed if the anomaly of water (max. density at +4°C) not exists. Else ice would sink down on ground and water would frozen from below to top.

    The "fine tuning" for life developement is found at any level.

    The fact that the distance of the moon is very well balanced is as frappant. (see Miles drake5:20 PM, December 11, 2019)

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  52. Stephen Hawking wrote an interesting paper, The Cosmological Constant and the Weak Anthropic Principle (pages 423-432, Quantum Structure of Space and Time, 1982): "it is based on the idea that the path-integral for the Universe has to be evaluated over compact Euclidean metrics with all values of the Euclidean 4-Volume."

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