Sunday, November 11, 2018

Guest Post: Phillip Helbig reviews “Lost in Math”

[Phillip Helbig worked in cosmology and gravitational lensing at Hamburg and Jodrell Bank Observatories and the Kapteyn Astronomical Institute. Although no longer employed in academia, he regularly attends conferences and writes book reviews for The Observatory, as well as the occasional journal paper. Phillip is a regular commenter on this blog.]

I've read a huge number of popular-science books, and my first impression is that Sabine's book is very well written. One could also think that Sabine is a native speaker (or, rather, a native writer) of English. The style is breezy without rambling, and direct quotations make it clear what the illustrious interviewees actually said, without any filter of interpretation (but see below for a caveat). Sabine's own position is very clear; this is almost an op-ed. Whether or not one agrees with her, this approach is preferable to introducing one's own biases into what might appear to the uninitiated as an objective description.

Enough praise; now for the critique. Let me emphasize, though, that I agree with everything which I don't discuss here, which is most of the book. In the interest of stimulating discussion, I'll concentrate on those few areas where I see things differently.

It is not always clear what needs to be explained. In discussions of fine-tuning and so on, one often reads about numerical coincidences, which imply that two numbers are roughly the same, but also about small (or large) numbers, which allegedly also need an explanation. (Since the inverse of a large ratio is a small ratio, I will speak only of small numbers in what follows.) It needs to be clear what is even potentially puzzling: it is always ratios near 1. In other words, if the smallness of some quantity is the result of a near cancellation, then that implies a ratio near 1 of the quantities which almost cancel; if the number is just small in relation to some other quantity because it has nothing to do with that other quantity, then it certainly needs no explanation.

Another aspect of the presentation I disagree with is the claim that the standard model has been "souped up" with dark matter and dark energy, as if these were some sort of epicycles, fudge factors brought in so that theory and observations match. On her blog, Sabine has often pointed out that general relativity says nothing about the sources of gravitation, so while dark matter might be interesting or even mysterious because we don't know what it is, it is not some sort of addition to general relativity. The same goes for the cosmological constant. Yes, Einstein initially introduced it as a fudge factor, and later abandoned it, but the universe is independent of the contingent history via which we have learned about it. From a mathematical point of view, one could just have easily included the cosmological constant from the beginning. Indeed, in other areas of physics, what is not forbidden actually happens, and if someone claims that something doesn't happen, that some quantity is 0, etc, then the burden of proof is on the person making the claim. Actually, what is interesting is that no fudge factors have had to be introduced. Despite a huge amount of cosmological data, a model with just a few parameters---all of which were known even back when there was almost no data---which was derived when there were some data but considerably less than now still fits the observations.

I have tremendous respect for George Ellis. However, I don't always agree with him, even on matters of science. I think that Sabine lets him too easily off the hook because they seem to agree on many issues. Ellis dismisses the idea that we could be living in a simulation, but is careful to point out that science cannot disprove the existence of God. One could just as well say that we cannot disprove that we are living in a simulation and dismiss the idea of God. Strictly speaking, one can disprove neither, but can use various arguments to discuss the probabilities of both. Also, after criticizing certain ideas as being non-scientific, Ellis says of one of his own ideas, that nothing is physically infinite: "There's no way I can prove it.... But we should use it as a principle." This isn't the place to argue with Ellis; my point is that if Sabine could be obstinate enough to stay in Weinberg's office even after he had essentially asked her to leave, she should have called out these two obvious contradictions on the part of Ellis. I think that this is a good example of confirmation bias. (Interestingly, Tegmark is also critical of the idea of physical infinity but, in contrast to Ellis, is a strong proponent of the multiverse.)

My main disagreement with Sabine concerns fine-tuning. I think that this is due to an unnecessary attachment to probability. Many normally think that fine-tuning and low probability go hand in hand. As Sabine points out, though, without knowledge of the underlying probability distribution, one cannot say whether an anthropic explanation involving the multiverse leads to likely values. But is that even necessary? One can discuss fine-tuning for life, in the sense that slight changes of various parameters (within the otherwise allowed range) would lead to a universe incompatible with life. There can be absolutely no debate that the universe is fine-tuned in this sense. Whether the values we observe for the physical constants are likely in some sense is unknown, but also irrelevant. One must be careful not to confuse fine-tuning in the particle-physics sense of lack of naturalness (discussed above) with the case of values being within a small region of possible parameter space (regardless of how likely that small region is by some definition.) As an aside, it is not true, as Sabine claims on p. 114, that fine-tuning goes away if one considers many changes simultaneously. A good discussion of fine-tuning, which also rebuts many common objections, including that one, can be found in the book by Lewis and Barnes.

It is also beside the point whether, also mentioned on p. 114, somewhere in parameter space there is another region compatible with life; the point is that most of it is not. A good comparison is with the "coincidence" that the Earth is just at the right distance of the Sun for the existence of life. The explanation is simple: there are many solar systems with planets at various distances from their stars. By chance, some will be at the right distance for life. It is also completely irrelevant how likely these are, as long as the probability is non-zero. The same goes for the multiverse. Given the multiverse (perhaps a daunting proposition), then fine-tuning is not puzzling at all. A good case for the multiverse is made by Max Tegmark. (Lewis and Barnes mention the multiverse in a book about fine-tuning; Tegmark does the opposite.) I think that most examples of fine-tuning are real; again, the book by Lewis and Barnes is a good summary. In one famous case of alleged fine-tuning I disagree, and that is the flatness problem. I wrote an entire paper about that, so I won't say much about it here. I'm also sure that most of the people who have thought much about the multiverse don't make this simple mistake.

Suppose I flip a coin a hundred times and it comes up heads every time. It seems that Sabine would say that this outcome is just as probable as any other outcome (which is true) and therefore that there is no reason to assume that the coin is not fair (which is false). I think that most people would disagree with Sabine, and I agree with those people. If one must discuss probabilities in conjunction with fine-tuning, or vice versa, what is relevant is not the probability per se, but rather the probability relative to some situation which is important to us.

A common theme in Sabine's book is that fundamental physics, having become "lost in math", has not made much progress in recent decades. This is a correlation, but is there a causation? Perhaps the problems are just really hard theoretically, and experimentally nothing is accessible at the moment. In neither case would this be the first time that something like this has happened. Thus, while I sympathize with the main theme of the book, I don't think that there is a watertight case for the claim.

Perhaps other approaches will be more successful, but the burden of proof is on those who make such claims. Yes, maybe progress is difficult due to lack of funding for those thinking outside the box, and without funding, it is difficult to prove whether an alternative approach would pay off.

Does beauty distract us from truth? Perhaps, in some cases, but in these I claim (probably agreeing with Sabine here) that it is not beauty per se, but rather a false sense of beauty. Aesthetics in some sense, perhaps something similar to Pirsig's "quality", has been a useful guide in some cases. At the end of the day, though, the route to truth doesn't matter; a successful theory is a successful theory regardless of the path trough which it was arrived at.



Some comments from me:

First, as you can see, Phillip unfortunately used his review to propagate his own notion of fine-tuning. I therefore want to warn you that this is not the way most physicists use the word and therefore not the way I use the word in my book. Please don't let yourself get confused.

Second, Ellis correctly points out that the simulation hypothesis is not science because you cannot disprove it. This is totally in line with him saying that science cannot disprove god. And, yes, Ellis puts forward metaphysical principles, but in contrast to the other physicists I spoke to, he is aware that these are unprovable.

Third, I discuss the issue of fairness in the interview with Weinberg using the example of poker. It's a useless objection because we have equally little idea what counts as "fair" in the multiverse as we know the probability distribution. Neither of those are notions that make sense scientifically.

Fourth, I address the often-raised claim that progress has slowed down because "the problems are just hard" right in the beginning of the book. To sum it up once again: no one can tell how much of the slow-down is due to the problems being harder, but certainly using flawed methodologies will not help.

Fifth, I don't think there is anything like a "false sense of beauty". You decide what is beauty for yourself. Just don't mistake your sense of beauty for a scientific criterion.

130 comments:

Phillip Helbig said...

Some comments on Sabine's comments on my comments on her book:

"First, as you can see, Phillip unfortunately used his review to propagate his own notion of fine-tuning. I therefore want to warn you that this is not the way most physicists use the word and therefore not the way I use the word in my book. Please don't let yourself get confused."

It's hard to be clear in 1500 words. :-) Sabine's book is mostly about the "lack of naturalness" fine-tuning. If one reads other books about fine-tuning in the context of physics, one finds that there are other definitions as well. (I thus wouldn't say that any notion is "my notion"; at least, as far as I know, I haven't introduced a new definition.) The lack-of-naturalness definition is perhaps most common among particle physicists. See the books by Lewis and Barnes and edited by Carr (links above) for extensive discussion in a wider context.

"Second, Ellis correctly points out that the simulation hypothesis is not science because you cannot disprove it. This is totally in line with him saying that science cannot disprove god."

True. However, Ellis believes in God but not in the Multiverse. :-) It would have been interesting to find out why.

"And, yes, Ellis puts forward metaphysical principles, but in contrast to the other physicists I spoke to, he is aware that these are unprovable."

He's always been careful to point out what are assumptions, what are theories, and so on. I don't always agree with him, but respect his attention to detail.

For those wondering who Pirsig is, Google is your friend.


Sabine Hossenfelder said...

Phillip,

My book is neither about finetuning nor about naturalness. It's about physicists who don't realize they are using rotten criteria for theory development. I don't know what's the point of discussing 80 different definitions of finetuning; it's totally besides the point and the reader wouldn't have had any benefit from it.

But to be clear about the reason for my above warning to the reader: you state "if the number is just small in relation to some other quantity because it has nothing to do with that other quantity, then it certainly needs no explanation." This is totally not the case and I don't know why you would make such a statement, see eg the whole story with Dirac's large number hypothesis which I discuss in the book. No, the notion of finetuning I have in the book is not specific to particle physicists. What is specific to particle physicists is the notion of technical naturalness in particular.

Phillip Helbig said...

My book is neither about finetuning nor about naturalness. It's about physicists who don't realize they are using rotten criteria for theory development.

Yes, mainly. I also mentioned that I agree with most of the book, but highlighted things which I found somewhat confusing, or where I think that other people might find them confusing.

I don't know what's the point of discussing 80 different definitions of finetuning; it's totally besides the point and the reader wouldn't have had any benefit from it.

Both terms (naturalness and fine-tuning) occur in the book. They also occur in other books, sometimes with different meanings. This can be confusing to some people, especially if it is not clear which definition is being used.

But to be clear about the reason for my above warning to the reader: you state "if the number is just small in relation to some other quantity because it has nothing to do with that other quantity, then it certainly needs no explanation." This is totally not the case and I don't know why you would make such a statement, see eg the whole story with Dirac's large number hypothesis which I discuss in the book.

What motivated Dirac was not so much the fact that gravity is weaker than the strong force by 40 orders of magnitude, but that the same number, 40 orders of magnitude, is the ratio of the size of the observable universe to the size of a proton. (It is also the square root of the number of particles in the observable universe.) To keep these two numbers the same while the universe expands, he postulated that gravity weakens with time. Dicke later came up with a better explanation. Why should one think that small numbers per se need an explanation, e.g. the size of a giraffe compared to the size of the Milky Way? (This is what I mean by two numbers which have nothing to do with each other.) What might need an explanation is a number which is small because of a near cancellation, which implies that two other numbers are almost the same.

Alas, blog comments are probably too brief to discuss things in detail. The last time I discussed this topic with someone for a couple of hours, I think I had him convinced by the end. :-)

No, the notion of finetuning I have in the book is not specific to particle physicists. What is specific to particle physicists is the notion of technical naturalness in particular."

I agree with the second sentence. I also agree with the first; it is not specific to particle physicists. Still, there are other definitions used outside of particle physics.

Uncle Al said...

"My main disagreement with Sabine concerns fine-tuning. " Sakharov criteria define vacuum geometry of our net matter universe – ppb-broken symmetries, particularly parity. Noether's theorems, exact symmetries specifically excluding parity slop, source physical theories’ furious fudge pots.

Pseudovectors (axial vectors) retain signs when coordinates are inverted. Improper rotations glitch 3D pseudovectors. Proton versus antiproton magnetic moments exhibit Sakharov divergence, then ignored.

Probe vacuum geometry with questions excluded by beauty. It happened with a different molecule for another reason (DOI:10.1002/anie.201704221). 400,000 failed theorist years oppose a crafted molecule and one microwave rotational spectrum. Empirically sterile theory versus experiment, elephant versus mouse,

https://www.youtube.com/watch?v=GTuS1ISYEak
… look.

Alfonso said...
This comment has been removed by the author.
Unknown said...

What really has been discovered so far? Lovely geometry (SR & GR). Plus QM, which is of a totally different nature: QM follows from the observer, not from what is (allegedly) being observed. Plus, the Standard Model (perhaps children's toys?). And what has NOT been discovered? The nature of the dark matter.

Phillip Helbig said...

@Alfonso: I doubt that any serious scientist---neither Sabine, nor Weinberg, nor anyone else interviewed in the book, nor anyone who actually publishes in reputable journals---would in any way, shape, or form disagree with the Weinberg quote at the top of your post. He was referring to the sizes of the planets, their relative distances, and so on. While these are not completely random, neither are they the outcome of some basic law of nature (an idea which Kepler pursued for a while). Like the evolution of life on Earth, they are the product of contingency.

Samu said...

Hello, Sabine.

I'd like to ask you one question about the clear slow down occuring in theory physics from decades now (specifically in the sense of no new theory with experimental support since the standard model epoch).

Do you think it could be the case any new support evidence may be already far beyond the reach of human engineering? If the LHC (and even the future LHC-HL) were unable to find any clue of physics beyond the standard model (as it seems it could be the case if the mass of the "next" particle is not in the range of order O(1) TeV), maybe we could get stuck for centuries or millennials before we can build a particle accelerator able to find particles in the mass order of O(10) TeV? And what about if the new "clue" is in the range of the O(100) TeV?

Do you think in summary if we could be facing an instrumental problem that could stop the physics with experimental support for hundreds of years? And if that were the case, what could we expect about the future of the physics? Who is going to invest in this field once it is clear no support will be available for hundreds of years (in the best case)?

Best regards,
Samuel.

JimV said...

"Ellis believes in God but not in the Multiverse..."

I can't answer for Dr. Ellis of course, but I would pick the opposite if I had to choose, so perhaps my feelings have some bearing (in reverse). Which are that the two are conflicting notions. One postulates that this universe was a specific, intentional creation, the other (usually) that it is just one of very many possibilities, produced randomly. I see a lot of random activity in this universe and it seems to me to be the basic driver of both biological evolution and human technology, in the form of random trial-and-error. Dr. Ellis must have some other insights that guide his thinking against randomness. Many do, and I have seen so many such arguments that I feel it is unlikely his would be new, so I doubt the discussion of them would have added anything to the book.

Dr. Ellis and I do agree that the infinite and the infinitesimal seem to us to introduce unnecessary paradoxes, and that a tremendously large but finite universe (and nothing infinite in the inverse direction except zero) is easier to understand. (I am happy for this agreement; Dr. Ellis if he was aware of it would probably not be as happy.) This discussion too, though, would have been a digression to the purpose of the book.

(His notion of God should not be an infinite one either, then? Now I am curious.)

Simulation vs. god creation: also a puzzling dichotomy to me, as the only way I can make sense of the god hypothesis is that this universe is a simulation in the mind or computer of a god-like being or beings. The simulation runs by itself once started, based on programmed algorithms, but a programmer can hex-edit the data at any time to produce miracles. I suspect Dr. Ellis has a different simulation concept in mind. Well, no book can answer all questions, so "always leave them wanting more" is a good tactic.

Thanks for the post.

Helen said...

''A common theme in Sabine's book is that fundamental physics, having become "lost in math", has not made much progress in recent decades. This is a correlation, but is there a causation? Perhaps the problems are just really hard theoretically''

What?! This is an unfair statement, methinks. The whole point of the book is that the field stagnated _because_of_ passionately following theories that refuse to give up (or even die) in the face of many obvious problems, dead-ends, and unscientific methodologies.

Tanner said...

This is never a good sign when trying to rebut an argument “[f]irst, as you can see, Phillip unfortunately used his review to propagate his own notion of fine-tuning. I therefore want to warn you that this is not the way most physicists use the word and therefore not the way I use the word in my book. Please don't let yourself get confused.” It raises the suspicions of the reader about the rebutter.

TransparencyCNP said...

Another review, with bad drawings:
https://mathwithbaddrawings.com/2018/11/07/when-the-math-is-pretty-but-the-truth-aint/

qsa said...

Sabine

I find you position very very confusing and contradictory. One one hand you say "lost in math" then you say that nature is more complicated i.e. more math is needed as if the already used math is not so complicated. Maybe I am just not understanding you position correctly.

Sabine Hossenfelder said...

Samuel,

No, I don't think so. New physics doesn't equal the production of new particles. That's for two reasons. First, new particles, if they exist, make contributions also at low energies, it's just that those contributions are small. This means you have to do high precision measurements rather than high energy bombardments to see them. Don't get me wrong, I think it's a cleaner signal if you actually go and produce them, but the high precision avenue is possible and it's bound by technological sophistication and patience, not by size and energy limitations. (See eg the g-2 experiments or measurements of the electric dipole moment of the electron.)

Second, there are a number of feasible experiments that are promising but haven't yet been done and those are in areas where we know reliably something new must be happening. That's what concerns dark matter and the perturbative limit of quantum gravity.

Just generally I think what's in the way of progress is not instrumental problems but stupidity. Best,

B.

Sabine Hossenfelder said...

qsa,

Did you read the book?

Sabine Hossenfelder said...

Tanner,

Well, it's true. I suggest you stick with debating the content of my argument rather than attempting to discredit me just because you don't like what I say. I have been abundantly clear in my book what I am talking about and it doesn't add anything to the debate if a reviewer goes and adds their own notion of this or that.

Phillip Helbig said...

"What?! This is an unfair statement, methinks. The whole point of the book is that the field stagnated _because_of_ passionately following theories that refuse to give up (or even die) in the face of many obvious problems, dead-ends, and unscientific methodologies."

Of course that is the whole point of the book. Sabine already commented on this above. My point is that one shouldn't completely rule out other explanations. We should avoid a tendency I see in some commentators here, though, namely: "Sabine wrote a book about it, so the case is closed, and all those Nobel Prize winners are talking bullshit". That's an exaggeration, but only slightly. :-|

JeanTate said...

Samu: we know that the universe produces particles with energies of 10^20 eV and above; they are called UHECRs (ultra-high energy cosmic rays; perhaps the threshold is 10^18 eV?). Studying these, and trying to work out how they are created, and where, is not easy; however, such research might provide enough experimental/observational data to test at least some BSM physics.

Advances in high energy physics do not have to come solely from particle accelerators, nor even from lab-based experiments.

MartinB said...

@Phillip
Considering the argument "One can discuss fine-tuning for life, in the sense that slight changes of various parameters (within the otherwise allowed range) would lead to a universe incompatible with life. " I have a question. Whether a region in parameter space is large or small depends on how you define your parameters, doesn't it? Consider a parameter that can take values between 0 and infinity. I could convert it to a parameter with values between 0 and 1 (using tanh or exp(-x) or whatever function I like), so the metric of parameter space strongly depends on how you formulate your theory.

So what a large or small region of your parameter space is depends on how exactly you formulate your equations and I don't think that there is a "natural" way of defining the size of the parameter region, unless you have a bunch of universes and can check... Although I think this is not stated this way in the book (or is it?), I always assumed that Sabine also means this when she talks about "probability distributions" and thus did not want to become too technical.

Quant said...

The last issue of Physics Today had a review of the book by Nobel Prize Winner Wilczek. I would be interested in reading S. Hossenfelder's reply to that.

Sabine Hossenfelder said...

Quant,

Wilczek just repeats what he already said in the interview that is in the book and I already said there what I think about his idea that we "need more beautiful ideas". I find it somewhat peculiar that Physics Today picked a reviewer who is interviewed in the book.

Arun said...

So,
1. Is a broken symmetry beautiful or ugly?
2. Does the context matter - i.e., in some contexts, a broken symmetry is ugly and in others, it is beautiful?

Louis Tagliaferro said...

Phillip Helberg said… “Another aspect of the presentation I disagree with is the claim that the standard model has been "souped up" with dark matter and dark energy, as if these were some sort of epicycles, fudge factors brought in so that theory and observations match.”

While it is plausible there may be matter or energy that exists in an unobservable state that accounts for current observations, science has often historically proposed incorrect ad hoc solutions to explain observations that didn’t fit the accepted science of the time. When will scientists learn from mistaken past behaviors of first jumping to an ethereal explanation in order to preserve existing belief? Perhaps exhausting empirical and more rational possibilities should come first. The current generation usually, and incorrectly, equates their growth in knowledge with behavioral growth thus continuing a cycle of bad behaviors. At this point in time, whole heartedly accepting dark matter and dark energy is bad science indicative of past mistakes. It is way too soon to choose the intangible.


Phillip Helberg said… “ From a mathematical point of view, one could just have easily included the cosmological constant from the beginning…. if someone claims that something doesn't happen, that some quantity is 0, etc, then the burden of proof is on the person making the claim.”

I disagree with the burden of proof argument; if something doesn’t happen where a quantity is 0 then the burden is with those who propose there is some non-zero quantity. There is no proof god exists, proving there is no god (god = 0) is akin to proving a 0 quantity. Believing in something with no proof is faith, believing in evidence is science and scientist should be able to prove a non-zero quantity.

JimV said...

Beauty is a vague concept because most of us differ in what we consider to be beautiful. Some people love classical music, I prefer the Blues. My mother loved poetry; I find it difficult to understand most of the time.

My oldest brother had a paperback book of science-fiction short stories which I read at a young age. One was about a future after a nuclear war in which a race of mutated, intelligent bears was dominate and the human race was nearly extinct. One chief among the bears gathered some of the remaining humans and offered to protect and feed them if they would make beautiful things for him, such as he had seen among the ruins. So they worked and after a month or so he asked to see what they had made. They showed him paintings and clay sculptures. He smashed them in a rage and shouted, "I asked for beautiful things, not this trash! Here, these are beautiful things," and he showed them a knife and an axe.

So I can agree that we need more beautiful ideas, that is, ideas which I would find beautiful, but I am not sure what anyone else means by that. Maybe ideas that are useful would be easier to agree on.

Samu said...

JeanTate:
"Samu: we know that the universe produces particles with energies of 10^20 eV and above; they are called UHECRs (ultra-high energy cosmic rays; perhaps the threshold is 10^18 eV?). Studying these, and trying to work out how they are created, and where, is not easy; however, such research might provide enough experimental/observational data to test at least some BSM physics."

But these cosmic rays are rare events (and very arbitraries in momentum and other states). How are you going to do statistical experiment studies in this way? I would like to know the opinion of Sabine but I think UHECRs barely can serve as a alteraty to particle accelerators.

Alfonso said...
This comment has been removed by the author.
sean s. said...

Ellis dismisses the idea that we could be living in a simulation, but is careful to point out that science cannot disprove the existence of God. One could just as well say that we cannot disprove that we are living in a simulation and dismiss the idea of God.

I think the sociological implications of God and of multiverses are more than sufficient to justify using more care with one (God) than with the other (multiverses). One could just as well reverse the two, but even scientists need some sensitivity to how their words will be read. Perhaps George Ellis chose to “pick his fight”. That’s pretty wise, actually.

sean s.

Narad said...

Ellis dismisses the idea that we could be living in a simulation, but is careful to point out that science cannot disprove the existence of God.

It can't prove the noumenal existence of plural minds, either.

Enrico said...

@Philip

“Ellis believes in God but not in the Multiverse. It would have been interesting to find out why”

That’s easy. Belief in God is religion not science. Ellis knows religion does not teach the Multiverse so he rejects it. Unfortunately, many physicists mistake the Multiverse for science.

“we cannot disprove that we are living in a simulation and dismiss the idea of God. Strictly speaking, one can disprove neither, but can use various arguments to discuss the probabilities of both”

The business of science is to explain observations. These are called hypotheses. Simulation and God explain either nothing or everything. They are not scientific hypotheses. It is not the business of science to disprove either. Leave that to philosophy and theology.

How do you calculate the probabilities of simulation and God? Two ways to calculate probabilities: A priori knowledge – you can calculate the odds of various poker hands before the game because you know the number of cards in a deck and how many kings, queens, jacks, etc. A posteriori knowledge – you don’t know what game of chance is being played but you have information on the number of games played and the outcomes of each game. This is inverse probability or Bayesian inference.

Guessing the probabilities in Bayes’ theorem is a guessing game. Nothing to do with probability theory and statistics. Disreputable as Pascal’s wager.

“My main disagreement with Sabine concerns fine-tuning. I think that this is due to an unnecessary attachment to probability. Many normally think that fine-tuning and low probability go hand in hand.”

If you detach fine-tuning and probability, there’s no need for the multiverse. You don’t even know if what is observed is improbable or inevitable. But since you cannot calculate the probabilities, the multiverse is an imaginary solution to an imaginary problem. It’s nonsense but you can write a lot of papers and sell a lot of books about the multiverse.

marten said...

I cannot stress enough these wise words of Baron Bodissey: "We must not confuse statistical probability with some transcendental and utterly compelling force".

Phillip Helbig said...

"Whether a region in parameter space is large or small depends on how you define your parameters"

Sure, but if your result depends strongly on your definition, it's not very useful.

Phillip Helbig said...

"science has often historically proposed incorrect ad hoc solutions to explain observations that didn’t fit the accepted science of the time."


Yes, but neither dark matter nor the cosmological constant is an ad-hoc explanation. What is the alternative to dark matter? At some, essentially arbitrary, point in human history, all matter in the universe must be detectable to our instruments. I'm not saying that there is nothing left to learn with respect to dark matter, just saying that it is not an ad-hoc hypothesis. For what it's worth, MOND, an alternative to dark matter in certain contexts, is a textbook example of an ad-hoc hypothesis. And it seems to work surprisingly well and has had many testable predictions confirmed.


"When will scientists learn from mistaken past behaviors of first jumping to an ethereal explanation in order to preserve existing belief?"

Neither dark matter nor the cosmological constant is an ethereal explanation.

What is your alternative?

Phillip Helbig said...

"I disagree with the burden of proof argument; if something doesn’t happen where a quantity is 0 then the burden is with those who propose there is some non-zero quantity."

Then read up on Noether's theorem (make sure you pick the right one; she has more than one), conservation laws, quantum numbers, symmetries, etc.

Lawrence Crowell said...

I am reminded of Schopenhauer who, in his pessimistic way, said in contrary to Leibniz that we live in the worst of all possible worlds He stayed how it appeared other planets seemed hostile. Modern space science bares this as true.

Phillip is likely right in stating how in a multiverse the internal structure of a cosmology occurs according to some probability distribution. This is then similar to stellar systems of planets. There may be as many as trillion trillion, or about a mole, planets in the observable cosmos. Earth is then maybe just a case where biology is possible. So Schopenhauer maybe right, but many dice rolls will contain apparently strange outcomes.

Potentially there is some other principle. I think this may be some extermination of complexity. Complexity and entropy are related to action. A large complexity in a cosmology requires a lower cosmological constant. This may imply some distribution of comic outcomes in a multiverse setting. Maybe Leibniz was right after all.

Michael John Sarnowski said...

Hi Sabine,

I think it may be difficult for physics to change. Those who follow the beauty principle, and I am talking about professionals, probably have some financial/survival benefits from continuing with this direction. Same with multiverse people or string people theory and so forth. People always come up with logically why they go in the direction they go. Many times however they are headed in a direction by accident and then come up with a logic of why they are going in that direction. Very hard to change minds. I think you are making a dent at it though.

sean s. said...

I disagree with the burden of proof argument; if something doesn’t happen where a quantity is 0 then the burden is with those who propose there is some non-zero quantity.

This assumes that the “zero quantity” has been proven. Until it is, those claiming the zero quantity have a burden of proof.

There is no proof god exists ...

None that I know of. Perhaps none that anyone knows of. But there was no proof the Earth was round – until the proof was found. The deistic zero-quantity claim remains open.

Probably there is no god; gods are unlikely enough to ignore. But my opinion is not a proof; no one’s is.

There is no proof god exists, proving there is no god (god = 0) is akin to proving a 0 quantity.

True, but a zero-quantity claim has a burden of proof.

Believing in something with no proof is faith, believing in evidence is science and scientist should be able to prove a non-zero quantity.

Eventually, yes. But there is no deadline on providing non-zero-quantity proof. Science recognizes no statute of limitations.

sean s.

JimV said...

"I cannot stress enough these wise words of Baron Bodissey ..." (Marten)

This is a large statement, possibly of no startling novelty. Nevertheless, as a generality, it affords a rich resonance of implications.

Well said.

MartinB said...

@Phillip
"Sure, but if your result depends strongly on your definition, it's not very useful."
O.k., I may be dense, but I thought this was exactly my point: how do you define the size of a region in a parameter space in a non-definition-dependent way?

When you talk about "slight changes in parameters" that would make life impossible, does this not depend on exactly how you define said parameters? If a parameter can take any value between 0 and infinity - isn't any finite region that allows for life "slight"? What happens if you define a parameter X that can in principle take any (positive) value, and allowed regions for life are between 0 and 1 - is this a small region? What if I reformulate the equations using X'=atan(X) as parameter; suddenly the allowed region is a significant part of the whole possible parameter space.

Saying that the region in parameter space that allows for life is small implies that you know what the possible parameter space is (and that your definition of said parameters/the metric you use in this space is somehow unique) - but since we only have one universe, any parameter simply has one value and we have no idea whether other values would be "possible" (in our universe, they obviously aren't and we don't observe any other).

Isn't that exactly (part of) Sabine's argument that we would need some kind of probability distribution? (@Sabine, please correct me if I'm wrong in understanding you this way.)

Uncle Al said...

An arXiv search, "proton decay," 250+ preprints. Will physics exhaust -log scales or planetary water? Neutrinoless double beta-decay is nonsense. BS is risk-free, limitless, guaranteed output.

Disallowing a net matter universe might source some glitches downstream. Observing falsification is terrifying on a linear positive axis, and one undergraduate day: DOI:10.1002/anie.201704221 with a different molecule. High risk; no research program.

Phillip Helbig said...

@MartinB: Read the book by Lewis and Barnes. There is a reason that they need a couple of hundred pages to explain this. :-)

Emmette Davidson said...

JimV, “Conflicting notions” indeed. But unlike poor Bruno on the right hand, Ellis sitting atop his – and others’ – shoulders surely sees the sublime necessity of quanta, to likely likewise imagine the quantum totality bounded. Nonetheless perhaps he, from same high perch, maintains Bruno’s eternality by imagining its ever evolving observers’ free will manifests via perfect – i.e. perpetual – distribution of probabilities within the self organized, interconnected system, which is to say emergent. Whereupon “miracles” would be expected at certain frequencies, perhaps even evoked within higher observers’ local limits. Thus, free will is not the illusion; rather local randomness gift (and a very good one too, as you’ve attested).

And on the wrong hand are deterministic worlds of infinite base simulations and the multiverse, where either you must be consoled that a doppelganger got your miracle if you didn’t, or wonder whether your preprogrammed thought of it should ever console you in such arbitrary worlds in the first place. ~ (c) 2018 Choose wisely. Cheers.

Emmette Davidson said...

marten, Perfect!
(JimV, Consider the source.)

MartinB said...

@Phillip
That seems a non-answer to me.
I really am to assume that the answer is so incredibly complex that even its essence cannot be reduced to a few paragraphs? Even full physical theories (like GR or the Standard model) can be sketched briefly, but this argument cannot?

JimV said...

I was considering reading the Lewis and Barnes book, so I read the linked review. It didn't sound promising because there was no mention of the authors considering the following points:

1) If this universe is fine-tuned for "life", what does "life" mean? Human life? DNA life? Life that can exist and thrive floating in the atmosphere of gas-giant planets? Self-reproducing magnetic fields?

2) If DNA life is meant, couldn't this universe have been much better fine-tuned for it (presuming to power to fine-tune exists), seeing as DNA couldn't have existed in the early universe of first-generation stars, and will not be able to exist naturally for more than a small fraction of the universe's expected existence, and even then only in about 0% of the universe's volume?

3) If any sort of self-reproduction which can evolve into complex forms is meant, how do they know other universes might not be capable of supporting some such unknown forms over a much longer span of existence and volume?

4) Intelligent Design as an ideology seems to me to be based on a lack of understanding of how design and intelligence work. They are not magic. I think they are another form of evolution, based on the same trial-and-error algorithm. The analogy of a Great Designer based on human design work is based on a misconception. Paley's watch evolved, just like the trees in a forest. If a solution exists, trial-and-error will find it (as long as one doesn't give up and recognizes errors as such). In this universe there is a small niche solution for DNA life on rocky planets with liquid water, and evolution found it.

Unless those issues are answered convincingly, I wouldn't get much out of the book, due to not sharing its assumptions, which sound anthropomorphic, or at least DNA-promorphic.

Phillip Helbig said...

"I was considering reading the Lewis and Barnes book, so I read the linked review. It didn't sound promising because there was no mention of the authors considering the following points:"

Compare the length of a book review to the length of the book. Obviously, all points can't be covered in a review. But all you mentioned are covered in the book. There is also an entire chapter rebutting common arguments against fine-tuning.

Phillip Helbig said...

"That seems a non-answer to me.
I really am to assume that the answer is so incredibly complex that even its essence cannot be reduced to a few paragraphs? Even full physical theories (like GR or the Standard model) can be sketched briefly, but this argument cannot?"


I'm not saying that it can't be done. However, if you are really interested in this, you should read the book anyway. Blogs have their uses, but are no substitute for real study. (That's probably one reason why Sabine wrote her book, by the way.)

Note that your "replace it with atan" argument, if true, would discredit the entire notion of sensible priors in Bayesian statistics. If it were true, someone else would have noticed this.

opamanfred said...

@Philip
Whether dark matter can be called an "ad-hoc hypothesis" is a matter of semantics in some way, nevertheless I think it does fit the bill. It's clear that, using the right amount of DM, distributed in the right way, it is not too difficult to reproduce the observations while keeping Einstein's equations intact. And sometimes, DM is not where it should be, and theoretically gives rise to unobserved features like dwarf satellite galaxies. Adding, on top of that, that it must be made of peculiar stuff that only interacts through gravity and was never ever observed in any other experiment, you must admit that "ad-hoc" is not such a bad definition.
Is MOND equally ad-hoc? Perhaps, but there is a crucial difference: it is much easier to tweak with the rhs of Einstein's equations (DM) than with the rhs (MOND). GR versions of MOND require stringent theoretical requirements, while DM's only constraint is that it fits the observations (and that it is compatible with some yet-to-discover beyond-standard-model theory...).

Unknown said...

Hi Sabine,
I have started to read your book. Before, it was Lee Smolin’s book “The Trouble with Physics”. In my view you are reporting the finalized diagnose.

What one can learn from history of physics when it stepped out the crisis is that the first step was always connected to a revision of the existed interpretations of observations, not new experiments, but a revision of the old ones. In other words, a new look on widely accepted interpretations (experimental data) is necessary. The classical example is Copernicus system versus Ptolemaic model.
If we see today a dead end of the old beautiful ideas that means that such revision is needed and it should result in a new beautiful idea (a more simple interpretation of observations).

On point more. Again if we look at the history of physics, we will see that it progresses together with our understanding of the concept of space. A revision of space is needed! (My view how it can be done is for other place.)

Best

Lawrence Crowell said...

I read Helbig’s review of Lewis and Barnes. I was curious about this because Barnes is renowned as an Intelligent Design (ID) advocate. Fine tuning is away to interpret a question about the world. It frames the question according to anthropic thinking. It may not be entirely appropriate; it is similar to concluding Earth and life are structured for our existence. Of course no evolutionary biologist would cotton to this. In physics we should be similarly cautious.

Anthropic principle thinking has become popular. I have some issues with this. Hans Bethe appealed to the age of the world based on biology and geology to argue for a nuclear power source of the sun. This might be compared to the weak anthropic principle. Anthropic principle thinking of this sort is with limits acceptable. This in a fine tuning setting means we need to raise questions on how the world permits the complexity we observe. It does not mean we have to accept fine tuned world as some fiat.

The issue with our existence would in my thinking be really remarkable if we were in a universe that prohibited our existence. I this would open the door to some sort of ID reasoning.

Phillip Helbig said...

"I read Helbig’s review of Lewis and Barnes. I was curious about this because Barnes is renowned as an Intelligent Design (ID) advocate."

True. I mention this in the review, and also that Lewis is not (nor am I). However, the question of whether the universe is fine-tuned is independent of whatever explanation one has for it (there are others, e.g. a simulation). One shouldn't reject the argument because some people draw wrong conclusions from it. (For example, one shouldn't deny that organisms are well adapted to their environment just because some see this as proof of divine creation (as opposed to evolution).)

Phillip Helbig said...

"Whether dark matter can be called an "ad-hoc hypothesis" is a matter of semantics in some way, nevertheless I think it does fit the bill. It's clear that, using the right amount of DM, distributed in the right way, it is not too difficult to reproduce the observations while keeping Einstein's equations intact."

True. But this doesn't mean it is ad-hoc. What is the alternative? That all forms of matter in the universe should be detectable to our senses? Why?


"And sometimes, DM is not where it should be, and theoretically gives rise to unobserved features like dwarf satellite galaxies."

This is a (relatively robust) result of dark-matter--only simulations. Whether it is still a problem in more realistic simulations is not clear. (Some say it is, some say it is not.)

"Adding, on top of that, that it must be made of peculiar stuff that only interacts through gravity and was never ever observed in any other experiment,"

What is peculiar about that. I think that is more peculiar to assume that the universe must be made mostly of the same stuff of which we are made. Why? It would be like assuming that most of the mass of the universe must be in planets because we live on a planet.

"it is much easier to tweak with the rhs of Einstein's equations (DM) than with the rhs (MOND). GR versions of MOND require stringent theoretical requirements, while DM's only constraint is that it fits the observations (and that it is compatible with some yet-to-discover beyond-standard-model theory...). "

True; I was referring to non-relativistic MOND. There is probably not a better example of an ad-hoc theory. (A theory's usefulness is independent of its origins; in contrast to many ad-hoc theories, MOND has had testable predictions confirmed.) As for relativistic MOND, there is no good candidate theory; many have been ruled out in just the last year or so (different propagation speeds for electromagnetic and gravitational radiation, different Shapiro delay, etc.)

Sabine Hossenfelder said...

opamanfred,

MOND does not tweak either side of Einstein's equations, it's a non-relativistic limit. And the idea that it makes a difference which side of the equations you tweak is just wrong, because you can always go and solve the equations for what was previously either one side. Please watch my video to understand what's the difference between modified gravity, MOND, and dark matter.

opamanfred said...

sabine,
I know that MOND is nonrelativistic. But even Poisson's equation has a lhs and a rhs ;). MOND modifies only the lhs (the Laplacian) but not the sources (rhs). DM invents new sources but leaves the underlying equation unchanged.

Sabine Hossenfelder said...

opamanfred,

The Poisson-equation is not Einstein's equation and both theories modify the source terms.

Uncle Al said...

An army of Euclidean geometers curve fits deep sea navigation (elliptic space).
An army of Euclidean geometers curve fits reactor cooling towers (hyperbolic space).
When will the two armies unify 2-D space while postulating a triangle's three internal angles must sum to 180 degrees?

An army of physical theorists curve fits gravitation (general relativity).
An army of physical theorists curve fits uncertainty (quantum field theory).
When will the two armies unify physics while postulating baryogenesis' vacuum symmetries are invalid?

JimV said...

"Obviously, all points can't be covered in a review. But all you mentioned are covered in the book."

Okay, but for me those are important points, particularly a definition of life which leaves room for the unknown. Not to have them mentioned in a review, or to see any hint of answers to them in response to my comment, together with the fact that I have seen them ignored or misunderstood by other proponents of fine-tuning, makes me very suspicious that I would appreciate the book's treatment of them. One could say that some books by creationists about the Genesis Flood cover geologists' objections, but do they cover them well? (Probably not a fair example but it illustrates my degree of uncertainty based on past experience.)

It is known that humans can make patterns out of random features on the surface of Mars. Perhaps it is fair to argue that in some sense those features were fine-tuned to fool our perceptions due to the fact that they exist and have that effect. If that is the kind of argument Lewis and Barnes make, it is not as bad as the creationist example, but still not one I would be interested in. What is the likelihood of a universe with complex mechanisms not having any niche for any unknown form of life anywhere at any time? Until we know that number, which is probably unknowable, I don't see how the subject of universe fine-tuning has any scientific relevance.

And yet ... apparently some rational people do. Maybe there is a gap in my knowledge or thinking, which the book could fill. I must balance that against the annoyance an ID proponent who has probably never been part of a design team or been issued a patent is almost certain to give me.

Louis Tagliaferro said...

@Sean S. & @Phillip Helbig,

Zero by definition is no quantity, nothing. The absence of phenomena or evidence of any kind is by definition and default proof of zero. Saying a burden of proof lies with one who claims there is no quantity when by default no evidence or phenomena is that very proof is quasi-scientific and nonsensical to me. I’m repeating myself in saying, believing is something with absolutely no evidence is faith, science demands evidence. It is rational, logical, and scientific to require a claim of a non-zero quantity be supported by evidence, not the other way around. Where is the logic and science in your argument claiming otherwise?

Armin said...

To Phillip Helbig,

In general, when someone points out a problem with an argument of yours and you tell them to go read a book instead of addressing it, I consider that an admission that you lost the argument.

Steven Mason said...

Phillip wrote: Perhaps the problems are just really hard theoretically, and experimentally nothing is accessible at the moment. In neither case would this be the first time that something like this has happened.

Yes, I share that view. To people who say we aren't making much progress, I like to quip that we should wait a couple hundred years before we start to worry. Like you, I "sympathize" with the main theme of the book, that we might get lost in math (or get stuck in ruts). But Sabine's book is another voice in an ongoing discussion, because we've been discussing the relationship between math and reality since at least Plato (so-called Platonism in the philosophy of mathematics).

Phillip wrote: Perhaps other approaches will be more successful. Does beauty distract us from truth? Perhaps, in some cases, but in these I claim that it is not beauty per se, but rather a false sense of beauty.

Yes, well put. Didn't Sabine mention false beauty in her book?

Phillip wrote: It's hard to be clear in 1500 words.

I've been spanked for not being clear in 50 words. :-)

Steven Mason said...

Sean wrote: Probably there is no god; gods are unlikely enough to ignore.

As far as I can tell, someone who believes in God is akin to someone who believes in hurricanes. Both beliefs motivate people to guard against disaster. :-)

Sabine Hossenfelder said...

Zero is not nothing. It's a number with specific properties. It's the neutral element of the addition group of the integers. There are btw different zeroes, depending on what field and what operation you are talking about.

JimV said...

Armin wrote "In general, when someone points out a problem with an argument of yours and you tell them to go read a book instead of addressing it, I consider that an admission that you lost the argument."

I myself do not, having said something like that in a review meeting about a study which I had written a report on. ("Read the report.") It does seem to indicate a lack of time or patience to explain something to skeptics, as it did in my case. In hindsight I wish I had not done that, although I considered myself provoked at the time. Still it is natural to expect people to put in some of their own effort to understand something complex.

Louis Tagliaferro said...
This comment has been removed by the author.
Steven Mason said...

Jim wrote: If that is the kind of argument Lewis and Barnes make, it is not as bad as the creationist example, but still not one I would be interested in.

No, that isn't what Lewis and Barnes argue in their book, and I don't know why you would suspect that is the case. The book is merely a scientific primer on the concept of what we've come to call fine-tuning. The authors also include a chapter on how some people react to the concept.

Jim wrote: a definition of life which leaves room for the unknown

I don't recall any discussion (speculation, actually) about other forms of life that might exist if the universe was "tuned" differently. If that's what you're looking for, sure, skip the book. For that matter, we can't claim that we know everything about life in our own universe. You shouldn't expect a primer like this to focus on speculations.

Jim wrote: I don't see how the subject of universe fine-tuning has any scientific relevance.

Understanding how physical constants and laws took a certain form would have major scientific relevance in the context of understanding the nature and properties of matter and energy, which is, after all, what physics is all about.

Steven Mason said...

Sabine wrote: I don't think there is anything like a "false sense of beauty". You decide what is beauty for yourself. Just don't mistake your sense of beauty for a scientific criterion.

Let's get back to the book. First, I thought the whole point of Sabine's reference to beauty, and mistaking one's sense of it for scientific criteria, was precisely what was "false" about it. If one's sense of beauty leads to dead end, stagnant, wasteful, pointless, and stupid physics research, I think the metaphor of "a false sense of beauty" fits just fine, as metaphors go. Of course metaphors never work well when taken to unintended extremes. However, since this is Sabine's book, she's obviously the final authority on what she means by beauty and false beauty, and we should accept it. On the other hand, I'll suggest that she should acknowledge the reasonableness of other interpretations. In any case, even a misunderstanding about beauty doesn't distract from the main themes of the book.

Of course, there are other reasons for stupid scientific research. One of them is pure self-interest with no regard for integrity.

Oddly enough, I found the concluding chapter in the book redeeming, for lack of a better word. Don't get me wrong, the other parts of the book are fine and Sabine makes her points with refreshing clarity, verve and humor. Indeed, her claim that she doesn't appreciate American humor is belied by her frequent use of American-style humor in the book. To get an idea of what I mean, all you need do is look at the chapter subheadings. When I say redeeming, I'm referring to all the books written by experts in various fields who do a bang-up job describing problems and challenges, but offer nothing in the way of solutions, or solutions that are so vague they are virtually useless. Sabine offers good ideas for improvements. My only (unfair and unrealistic) criticism of the book is that I wish she would have offered much more.

There is so much to discuss about fundamental scientific research and applications research, public and private research, patents, etc., not to mention how to teach science, critical thinking and long-term thinking skills, ethics, etc. Do we have any idea how to create guidelines for how much of society's resources should be devoted to scientific research, how it should be allocated to various fields and subfields, and the mechanisms for getting and sharing those resources? Do our chances for survival as a species (and other species) depend on how we address these questions? Does it make the difference between thriving and merely surviving? The devil is always, always in the details. Sigh.

I would have felt annoyed if Sabine didn't have at least one chapter about solutions. She also points out - to those who don't already know - that scientists are people too. She makes this point with humor, and follows up with useful guidelines (established procedures, nothing new) for scientists to follow to guard against traps. She acknowledges that scientists won't always be successful at avoiding traps.

I think this book will join a growing number of voices within the scientific community to make improvements. In the final analysis, that is redemption enough.

Sabine Hossenfelder said...

Steven,

You write

"I thought the whole point of Sabine's reference to beauty, and mistaking one's sense of it for scientific criteria, was precisely what was "false" about it. If one's sense of beauty leads to dead end, stagnant, wasteful, pointless, and stupid physics research, I think the metaphor of "a false sense of beauty" fits just fine, as metaphors go."

No, it's a bad metaphor because it suggests I am saying using a sense of beauty is okay as long as it's the "right" one, which is of course nonsense. I say do not use your sense of beauty. I don't tell anyone whether their sense of beauty is right or wrong, I am simply saying don't mistake it for a scientific criterion. You have to badly misread the book to not get this point. There is nothing "false" about liking symmetries, or simplicity, or naturalness. It's just not scientific to use this preference for theory-development.

Alfonso said...
This comment has been removed by the author.
Louis Tagliaferro said...

Sabine, I was embarrassed reading my previous comment that I wrote and sent quickly without proof reading. Perhaps you can copy-paste the corrected version over it for me?

I didn't consider context such as charge, where zero can represent a neutral or balanced state, in such cases I withdraw my previous argument as it is clearly wrong; however when claiming the existence of some phenomena or energy for which there is no evidence I still maintain the burden should lie with the one making the claim since by default nothing is already evidence that nothing exists.

Steven Mason said...

Sabine wrote: it's a bad metaphor because it suggests I am saying using a sense of beauty is okay as long as it's the "right" one

I agree that would be a bad use of the metaphor; indeed, it would contradict the themes of your book. But that's not the way I interpret it. For the metaphor to work, one has to understand that one's "sense of beauty" can lead one astray, which brings us to false beauty.

I've been bombarded with warnings about false beauty since I was two-years-old, when my mother began reading fairy tales to me. Thousands of stories, fables and parables hammered the message in my head that true beauty is often found in the most unlikely and ugliest places. The moral: "Do not trust your sense of beauty! Look deeper!" Sabine, isn't that one of the themes of your book?

To me the metaphor simply suggests that "truth" is beautiful, even when it's not. In another post I revealed that I was raised Catholic but became an atheist in my teens. Some Christians think evolution and a godless universe is as ugly as it gets, that science is attacking everything that is beautiful and sacred. For me, the "ugly" truth is more beautiful than the Christian fantasy. I'll admit that an afterlife is an extremely beautiful idea to me, one that I would dearly wish to be true. Conversely, I find the idea of oblivion after death extremely ugly (though not nearly as ugly as suffering in hell for eternity). However, since I am aware that my sense of beauty can lead me astray, I realize that my desire for an afterlife is nothing more than wishful thinking, another kind of false beauty.

There's a line from one of your songs that hints at false beauty:

"I like to hear you breath
I'm not a talker
And if you think that's so romantic
It's just that I like you better when you don't speak"

To be continued . . . for some reason my entire post won't be accepted even though it conforms to the character limit.

Steven Mason said...

Sabine wrote: I don't tell anyone whether their sense of beauty is right or wrong, I am simply saying don't mistake it for a scientific criterion.

I beg to differ (and agree). When you refer to all the bad, wasteful, stupid physics research, and you write a book about how beauty leads physics astray, you are obviously telling people that their sense of beauty can be wrong, in the sense that it can lead them astray. Also, the phrase "lost in math" is just another way of saying "lost in beauty." (This makes sense only to people who find beauty in math) Yes, of course, you explain what is wrong with being led astray by a false sense of beauty, namely, mistaking it for scientific criteria.

Sabine wrote: There is nothing "false" about liking symmetries, or simplicity, or naturalness. It's just not scientific to use this preference for theory-development.

There's a contradiction in those statements. If it's "not scientific," it's false science. If "liking" a particular symmetry, simplicity, or naturalness is leading one astray, then the metaphor of false beauty works fine.

Let me offer an example. Consider Michael Behe, a biochemist who uses irreducible complexity to develop his God theory. For Behe, his theory is simple and natural, in contrast to evolution, which is absurdly complex and hopelessly unnatural. Anyone outside of Behe's bubble can plainly see that he is being led astray by a false sense of beauty, simplicity, naturalness, etc. He is a trained scientist engaging in the worst kind of self-indulgent wishful thinking. Sadly, I can assure you that Behe's books have sold many more copies than your book ever will (another ugly truth).

Sabine wrote: You have to badly misread the book to not get this point.

But I did get the point about mistaking one's sense of beauty for scientific criteria. I've quoted it several times and stated I agree with your point. As far as I can tell, you and I are disagreeing only on the use and interpretation of a metaphor. I've even stated that any misunderstanding I might have about the metaphor doesn't distract from the themes of your book. If I had any significant disagreement with any points you made in the book, I would tell you.

Steven Mason said...

Alfonso wrote: If we listen to the Schoenberg dissonant music . . .

We've all had the experience of hearing atonal music for the first time, which might be likened to tasting strong alcohol for the first time. What do you suppose it would be like to grow up listening only to atonal music and then hearing tonal music for the first time?

Or how about the case of someone who has heard no music for the first twenty years of his life? How would he react to tonal and atonal music? Would both seem strange and disagreeable at first?

If the blind violinist had played atonal music for Frankenstein's monster, would he have soothed or angered the savage beast?

If the so-called Mozart effect has a beneficial effect on the mental development of children, what effect would atonal music have? Would it enhance a child's analytical abilities? (By the way, I'm not a believer in the Mozart effect)

I've heard that children who grow up learning tonal languages - such as Chinese - have a better-developed sense of tone recognition.

In the history of Western music, some of the harmonies we consider consonant today were considered dissonant in the past.

Alfonso wrote: building the model at any price . . .

To be fair to physicists, they'd be the first to point out that their models are just models. There are lots of jokes about the models physicists make, and I'm pretty sure most of them come from physicists. It's Friday, so here's a classic joke:

Milk production at a dairy farm was low, so the farmer wrote to the local university, asking for help from academia. A multidisciplinary team of professors was assembled, headed by a theoretical physicist, and two weeks of intensive on-site investigation took place. The scholars then returned to the university, notebooks crammed with data, where the task of writing the report was left to the team leader. Shortly thereafter the physicist returned to the farm, saying to the farmer, "I have the solution, but it works only in the case of spherical cows in a vacuum".

Sabine Hossenfelder said...

Louis,

I cannot edit comments. I can only entirely delete them, but you can do that yourself.

JimV said...

Belated response to Emmette Davidson (because I just saw it), who said:
"marten, Perfect!
(JimV, Consider the source.)"

Response: Marten's source and mine were the same (science-fiction Grandmaster Jack Vance); it was an imitative homage.

Response to Steven Mason: I thought I made it clear that my comment was based on Dr. Helbig's review, and on his response to my comment, not on the book, which I haven't read. According to that review and response, the book advocates that this universe was fine-tuned for life, and deals with all my objections conclusively. You seem to be saying that the book does not so advocate and so does not deal with all of my objections (not using a general definition of life, for example). Your argument would seem to be mostly with Dr. Helbig.

However, nothing you stated made me reverse my provisional opinion that the hypothesis of fine-tuning for life has no scientific relevance on the basis of a single statistical sample (namely this universe). Science deals with testable predictions and repeatability. That this universe's laws and parameters would prove suitable for human life was a prediction of the Anthropic Principle, although the Tree Principle or Clay Principle would work as well. The fine-tuning principle as I understand it attempts to stretch that into a claim that this suitability is statistically unlikely among possible universes (the implication being that if the supposed tuning was not so fine it would not be so unlikely). Without a general and all-inclusive definition of life's possible forms and universes' possible forms, or a large statistical sample of universes, how can that claim be made? (I know, Dr. Helbig: "Read the book.")

Some of that may be based on my misconceptions, as your response seemed to be to me.

Steven Mason said...

Jim wrote: nothing you stated made me reverse my provisional opinion that the hypothesis of fine-tuning for life has no scientific relevance on the basis of a single statistical sample (namely this universe).

It didn't make sense that you would say the book might not be "as bad" as a Creationist book, so I clarified that it's a scientific primer on fine-tuning.

Physicists are working to understand how the constants, forces and physical laws got to be what they appear to be. We predict what happens if these parameters deviate just a little. "Fine-tuning" is a metaphor. Unless you have evidence that rules out a fine-tuning hypothesis, you can't claim it isn't scientifically relevant.

Fine-tuning doesn't make any claims; it's a proposition. It doesn't claim to know what the actual probabilities are, other than a vague reference to "unlikely." There are no fine-tuning advocates claiming that it is an established theory. Perhaps someday we'll discover that our universe is, indeed, unlikely, perhaps we'll find that it was inevitable. Or maybe we'll catch an exciting glimpse of those alternate forms of life you mentioned.

Emmette Davidson said...

JimV, But what of the true source: the underlying dual that tends to reverse things.

Emmette Davidson said...

With apologies to marten -- I cannot stress enough these wise words of a certain dying puppy, who surely sat atop many dead giants just to howl them at the moon: “Existence without non existence is a paradox if there is no medium to parallel them. That medium for all our understanding must consist of all probabilities manifested simultaneously and dynamically... The actual force of creation/destruction is possibility itself.”

So, in the matter of existence at this momentous time, who of baron or puppy has greater authority? Which should sway more: fearsome instruction of a fearful orthodoxy, or natural truth that itself speaks? And what are the chances the moon heard?

Steven Evans said...

" A good discussion of fine-tuning, which also rebuts many common objections, including that one, can be found in the book by Lewis and Barnes."

Let's not be apologists to the corruption of science, Phillip Helbig.

Is that the book "The Templeton Foundation have given me a few thousand dollars so I would just like to point out that General Relativity and Quantum Mechanics do not categorically rule out that Jesus' dad made universes for a living"?

Publish on the scientific record an example of fine-tuning for which there is provably a strong probability that it is not an accident or that it does not have an underlying physical explanation. You can't. Fine-tuning is pure speculation unconfirmed by observation. Therefore not physics.

Phillip Helbig said...

Yes, one of the authors, Barnes, appears to be a theist. The other isn't. Yes, he has received Templeton money. Several points. First, read the book if you haven't. Second, a true argument remains true even if it is misinterpreted or abused by the person making it. For example, organisms are adapted to their environment (also a type of fine-tuning), but that doesn't mean that some supreme being created them that way. If someone argues that, the answer is to reject and rebut his argument, not the claim that organisms are adapted. Third, I think it would be good if the scientific community, or at least those who are not openly religious, would agree to not accept Templeton money. It's almost like the tobacco industry sponsoring lung-cancer research. However, removing people who have accepted Templeton money, directly or indirectly, would remove several otherwise excellent scientists. Also, there are several examples where people who have accepted Templeton money have not played Templeton's tune in the slightest and remain convinced atheists. Templeton probably spreads its net as wide as possible, and accepts the side effect that some people don't dance to their tune. Some scientists take a practical view, saying that it is better to spend Templeton money on good science than on religious bullshit. tl;dr: rebut the arguments, don't make ad-hominem attacks.

Sabine Hossenfelder said...

Templeton does some good stuff. I know quite a few people who received money from them and for all I can tell it didn't come with questionable fineprint. I don't understand why so many people seem to have a problem with Templeton. My impression of the "donor's intent" is that Templeton wanted to understand the relation between religion, and science and I do think that's a topic which is both interesting and important.

Also, fwiw, in my own impression religious people are much more careful about separating belief from fact than non-religious people. In my book, George Ellis is the obvious example, but I have noticed that on various occasions.

Having said that, I agree with what people said above that if you don't want to sum up the supposed killer-argument from the book that seems like cheating. I have been exceedingly clear in my book in pointing out that there are ways to define fine-tuning, one of which you seem to have in mind here, but if you properly define it there's no reason why that's of any relevance. So, according to definition X the Higgs-mass is fine-tuned. So what?

No, you do not need probability distributions for the definition; you can define whatever you want. But the probability argument is what people use to explain why it's supposedly a problem. Some kind of "conspiracy". If you define "fine-tuning" without that (as it's the case, eg, for naturalness) you simply end up with some mathematical requirement that isn't indicative of any problem in need of a solution.

Phillip Helbig said...

"I don't understand why so many people seem to have a problem with Templeton."

Because they have an agenda, which is to spread the idea that science and religion are more compatible than they are. Of course, one can define religion such that it is automatically free of any conflict with science, but that is not what most people mean by religion. Much of the physics stuff they support is probably OK. In other fields, such as biology, less so. No tobacco company which supported research in lung cancer (yes, this really happened, on a large scale) wrote in the contract "you have to demonstrate that tobacco doesn't cause lung cancer, or else", but there is an obvious conflict of interest. Same idea.

Again, I know many respectable people who have accepted Templeton money, and none have changed their views as a result. The problem happens lower down, where people are more desperate for money. Perhaps not so much as people changing their views, but rather people who support Templeton's views already get funded while others don't, which introduces a bias which shouldn't be there.

I find it hard to blame the struggling student for accepting Templeton money. I know a conscientious objector who accepted a NATO fellowship, and an atheist who did his non-military service (i.e. an alternative to military service which was otherwise compulsory) in a church. People like John Barrow and George Ellis who are openly religious are also hard to blame for taking Templeton money.* However, I think that it would have been a good gesture for Martin Rees (who wasn't visible as a religious figure) to reject the Templeton Prize; he could afford to do so. (When a journalist asked him if he had already been a millionaire before the prize was awarded, he replied "no comment.)

_____
* Barrow and Ellis do, as far as I can tell, manage to keep their beliefs separate from their science. They both also belong to "liberal" congregations. For that matter, Georges Lemaitre, who was a priest (but not a Jesuit) and always dressed like one, even when doing science, kept the two apart.




Phillip Helbig said...

There is a highly blogosphere-visible biologist who has detailed why many scientists think that Templeton funding is a bad idea.

Phillip Helbig said...

"if you don't want to sum up the supposed killer-argument from the book that seems like cheating"

If your paper "Finetuning and Naturalness in the Foundations of Physics" appears in a respected journal, then I'll write a reply and submit it to a respected journal. :-) Sometimes, a comment box is too small for a good explanation (and one certainly can't accuse me of not trying). There is a reason why Lewis and Barnes wrote a book, and in particular an entire chapter which rebuts common arguments against their idea (which is a different sort of fine-tuning than that which you discuss in your book).

"I have been exceedingly clear in my book"

Yes. I presume that there is a reason why it is a book and not just a blog post. :-)

Sabine Hossenfelder said...

Phillip,

I just summarized my argument to make clear you do not have to read 200 pages to understand it. So your comment according to which I allegedly told you to read the whole book is wrong, and moreover doesn't make sense seeing that we all know you did read my book. It's hard to avoid thinking you're refusing to answer a straight-forward question because you have no answer. In any case, the lack of answer doesn't help your case.

Sure, you're welcome to wait until my paper gets published until you reply, alas the paper is not about fine-tuning is cosmology, as I write very clearly, and that's the topic you seem concerned with.

Sabine Hossenfelder said...

PS: Regarding Templeton, I didn't say everything they do is good stuff, but some of it is, and that I think the intent of studying the interface of religion and science makes sense.

Phillip Helbig said...

"I just summarized my argument to make clear you do not have to read 200 pages to understand it. So your comment according to which I allegedly told you to read the whole book is wrong"

I think that this is a misunderstanding...

"and moreover doesn't make sense seeing that we all know you did read my book."

...which supports the idea that your comment above is based on a misunderstanding.

"It's hard to avoid thinking you're refusing to answer a straight-forward question because you have no answer. In any case, the lack of answer doesn't help your case."

It's really not my case, but that of Lewis and Barnes. If anything, the discussion here shows that it is easy for people to talk past each other because terms are used differently, there are different cultures, and so on. Some things just need a longer explanation. Having said that, I'll try to answer any specific questions, i.e. not "summarize the book in the comment box".

"Sure, you're welcome to wait until my paper gets published until you reply, alas the paper is not about fine-tuning is cosmology, as I write very clearly, and that's the topic you seem concerned with."

Yes, and it's also not about the anthropic principle. I'm concerned with all things which I find interesting. :-)

Steven Evans said...

" organisms are adapted to their environment (also a type of fine-tuning)"
This is an explained scientific fact. Can you point to an observation on the scientific record from which it follows that the universe is fine-tuned? That there must be an explanation beyond the universe such as a tuning mechanism or multiverse? No, you can't. Fine-tuning of the universe is currently simply speculation.

"First, read the book if you haven't."
"A Fortunate Universe: Life in a Finely Tuned Cosmos" There is zero evidence on the scientific record that the cosmos is finely tuned. The title is mistaken and embarrassingly blatant evidence of an agenda. So I don't need to read on.


"I think the intent of studying the interface of religion and science makes sense"
The main tenets of religions have been shown to be incorrect. What else needs to be said? Apologies, this is off the subject of your book. Good luck with your work to find the right way forward for theoretical physics.

Phillip Helbig said...

" organisms are adapted to their environment (also a type of fine-tuning)"
This is an explained scientific fact.


Right. NOW it is. Before Darwin, it wasn't.

Can you point to an observation on the scientific record from which it follows that the universe is fine-tuned? That there must be an explanation beyond the universe such as a tuning mechanism or multiverse? No, you can't. Fine-tuning of the universe is currently simply speculation.

Had you lived before Darwin, you would have said "Can you point to an observation on the scientific record from which it follows that the organisms are adapted? That there must be an explanation beyond normal biology such as a tuning mechanism or multiverse? No, you can't. Adaptation of organisms is currently simply speculation."

"A Fortunate Universe: Life in a Finely Tuned Cosmos" There is zero evidence on the scientific record that the cosmos is finely tuned. The title is mistaken and embarrassingly blatant evidence of an agenda. So I don't need to read on.

You: It just ain't so, Guv'nor!
Lewis and Barnes: We discuss arguments in favour of our hypothesis and rebut common objections in a very detailed book.

Steven Evans said...

The concept of fine-tuning hasn't led to any actual physics in 40 years or more. A speculation based on the idea of fine-tuning is that there is a multiverse. There are no observations confirming the existence of a multiverse.
Have Lewis and Barnes moved this state of knowledge on any? Nope.

Steven Evans said...

Phillip Helbig in blog-post: " I think that most examples of fine-tuning are real;"

So you have evidence that it is *physically* possible that the claimed fine-tuning (constant, characteristic, force, etc.) could be different to what it is in this universe i.e. that it makes physical sense to talk about "tuning"? Not only that, you have evidence of the physically possible range of these tunings and have evidence that some outcome (life (definition?), complexity) is only possible in a small part of the range or is probabilistically low, so as to be able to label the tuning "fine"? You have evidence that a self-explanatory, multiverse-free TOE which explains away all so-called fine-tunings is ruled out?

Incredible! Let's hear it. You are like some sort of physics oracle.

So why don't you talk us roughly through one example? e.g. Tell us what all the physically possible values of the Cosmological Constant are and how you know that; tell us which values lead to "life" (define please) and how you know that.

I had a peep at the Barnes book on Amazon. He explains fine-tuning in terms of varying the ingredients of a cake. We can double the amount of flour in the cake and get a very different cake; now what if we double the mass of the electron? Facile nonsense, as expected. We know we can vary the ingredients of cake to give different cakes; it's not known that the fundamentals of physics can be varied to give radically different types of universes. Why does the Cambridge University Press publish such drivel? It's embarrassing for all involved.

Phillip Helbig said...

"Why does the Cambridge University Press publish such drivel? It's embarrassing for all involved."

It's most embarrassing to those who try to comment on the book without having read it.

If all the constants of nature could not take on any values, that would be a valid explanation. Where is your proof of this?

"I had a peek on Amazon" does not a qualified review make.

Steven Evans said...

"It's most embarrassing to those who try to comment on the book without having read it."
We have a noble free-speech institution where cranks can cry out that tweaking the Cosmological Constant shows Jesus loves you. It's called Speaker's Corner, not CUP.

"If all the constants of nature could not take on any values, that would be a valid explanation. Where is your proof of this?"

Surely you're joking, Mr Helbig?
Clearly, I am not claiming that it has been shown that the constants of nature *can't* take on other values. I am simply stating that there is zero *physical* evidence that they can. You state that you think fine-tuning is real, but you have again failed to point to any *physical* evidence that tuning is possible, fine or otherwise.

Why don't you tell me what *physical* evidence there is that the Cosmological Constant could be a different value to the one measured in this universe?

Steven Evans said...

And Big Daddy makes the same point:

'Steven Weinberg...acknowledges that he currently has no explanation (apart from a multiverse) for the smallness of the cosmological constant, but cautions that "It is still too early to tell whether there is some fundamental principle that can explain why the cosmological constant must be this small."'

Phillip Helbig said...

@Steven Evans: If we want to discuss the points made in the book, you have to read it. Come back when you have.

lukebarnes said...

Well, that was an interesting read.

* "Barnes appears to be a theist". Yep.
* "The other [Lewis] isn't." Also, yep.
* Yes I have received grants from the John Templeton Foundation.
* "Barnes is renowned as an Intelligent Design (ID) advocate". Nope. I have no beef with biological evolution. Neither does the book.

* "rebut the arguments, don't make ad-hominem attacks." Yep.

When I am Supreme Emperor of Spacetime, there will be a law that says: on pain of death, the sentence "I haven't read the book" must be followed by "and so I don't have an opinion about it."

Steven Evans said...

The point made in the book is that if certain fundamentals about the universe are different, you get a very different universe. But there is no physical evidence that these fundamentals can be different. You have failed to deal with this simple point and so does the book. It's disappointing you refuse to learn.

Steven Evans said...

@lukebarnes
And still you fail to deal with the simple issue that there is no evidence that it is physically possible for the Cosmological Constant, for example, to be any other value than it has been measured in the observable universe. Its value may end up having an explanation not involving fine-tuning The same applies to all other fine-tunings.
To claim that the universe is "fortunate" or the Cosmos is finely-tuned for life, as in the title of the book, is pure crankery. You haven't actually understood what physics *is*. Ooops.

Steven Evans said...

@lukebarnes
"Supreme Emperor of Spacetime, there will be a law that says: on pain of death,"
I love how religious fundamentalists always want to kill their critics..

Still no evidence provided that it is physically possible for purported fine-tunings to take other values than those observed...Just speculation about what would happen if they did. Not understood modus ponens then - Doh!
In a multiverse there would be Boltzmann Brains and possibly even LukeBarnes Brains. Anything is possible.

Phillip Helbig said...

@Steven Evans: Apart from not having read the book, which actually disqualifies you from discussion of it, consider the following: Your claim, based on no evidence whatsoever, is the that values of the fundamental constants, for some reason no-one knows, cannot take on any values other than the ones you observe. So not only do you violate Sabine's (correct but irrelevant here) complaint that you don't know the underlying probability distributions, you claim that you know them and that they are all delta functions!

From Luke's comments it appears that he agrees that I have understood his book. :-)

"Its value may end up having an explanation not involving fine-tuning The same applies to all other fine-tunings."

Yes, this is possible, but the burden of proof is on those making such a claim. In this case, you. As I note in my review of the book by Lewis and Barnes, there are about half a dozen explanations. The question is, which are most useful and most credible.

Steven Evans said...

@lukebarnes

I know you're reading, little Lukey, down there at the Fair Dinkum Academy of Boomerang Science.
Why don't you point to the evidence that it is physically possible for purported fine-tunings to take other values than those observed?

Because there isn't any and you are a corrupt crank.

Phillip Helbig said...

This is my last comment in the Steven-Evans thread, since a) he hasn't read the book and b) apparently has no better strategy than resorting to ad-hominem attacks.

Rob van Son (Not a physicist, just an amateur) said...

@Steven
"Still no evidence provided that it is physically possible for purported fine-tunings to take other values than those observed..."

Reading up on the philosophy of science would help you mightily. Especially Karl Popper can clarify the matters here (e.g., CONJECTURES AND REFUTATIONS).

The confusion under which you are working is that your claim comes down to "History could not have been different". The current constants of nature were set in the past. As history cannot be changed, we cannot rerun the universe and see whether the values can change. As history cannot be changed, questions about alternative histories are not empirical questions.

Now comes in philosophy. In your words, there never could be any (empirical) evidence that history could have been different, even if history, and the constants of nature, could have been different. That is, the hypothesis that history could not have been different is irrefutable. The question about alternative histories is not an empirical question, so asking for (empirical) evidence of the possibility that history could have been different is pointless.

I assume for the moment that you did not make such a pointless argument.

The question whether the constants of nature could have been different has a meaningful interpretation. That is simply the question whether our theories about nature allow for different values for these constants. That is obviously true. All our current theories contain constants with arbitrary values. That certainly is not the point.

The big question in theoretical physics, as far as I understand it, is based on the feeling that a theory is better if it has less "arbitrary" values for constants. The ultimate theory, then, would have 1 or 0 arbitrary (free) constants. However, there is no a priori reason to assume that the ultimate Theory of Everything exists, and if it exists, that this theory has no or only few arbitrary constants.

Now, such philosophical questions about alternative physical universes can be fruitfully discussed and might even be resolved on some level. Read, e.g., Karl Popper for a discussion on how to do this.

JeanTate said...

For HPS (History and Philosophy of Science), I prefer Lakatos to Popper, e.g. Proofs and Refutations

Steven Evans said...

@Phillip Helbig

Maybe English is not your mother tongue. Read my post again. I didn't write that the constants couldn't take on other values, I simply wrote there is no physical evidence that they can. Sorry to spoil your delta function punchline.

Let's make this really, really simple for you:

The Cosmological Constant has been measured to be a particular value.
Is it physically possible for it to be other values? This is not known.
How likely is it that it can take on other values? This is not known.

So we have *no idea* whether or not the Cosmological Constant can take on other values.

But you think it can.

Why?

You have provided zero evidence.

"The question is, which are most useful and most credible."
Fine-tuning has predicted nothing so has so far been useless, and there is no physical evidence for it, so it is purely speculation. Currently useless and incredible - you are plumping for that answer?

Steven Evans said...

@Rob van Son (Not a physicist, just an amateur)

Oh, what a lot you've written.

Don't worry about the bit in parentheses in your user name - nobody is going to confuse you for a physicist. Then again, looking at what Luke Barnes writes, keep it.

You have misunderstood what I have written, although it was extremely simple. The question is whether it is physically possible for the fundamental constants to be different values than those that have been observed. It is not known in physics why the constants are the values that they are, therefore it is not known whether they can be other values. The fundamental constants are not known to be arbitrary - that's the whole point. If we knew they were arbitrary we wouldn't be having this discussion.

" However, there is no a priori reason to assume that the ultimate Theory of Everything exists, and if it exists, that this theory has no or only few arbitrary constants."
I have nowhere claimed that a TOE must exist. It is fine-tuners who are ruling it out without reason.

"Read, e.g., Karl Popper for a discussion on how to do this."
That's sweet that you are telling me what to read after you completely misunderstood my utterly trivial point. Don't feel bad though - Luke Barnes (physicist, not an amateur) doesn't understand either.

Steven Evans said...

@Phillip Helbig "apparently has no better strategy than resorting to ad-hominem attacks."

I've asked you and Luke Barnes several times:

Why don't you point to the evidence that it is physically possible for purported fine-tunings to take other values than those observed?

You have failed to point to any evidence. Because there is none.
Speculating about the nature of other universes with different Cosmological Constants is not evidence that it is *physically possible* for the Cosmological Constant to take other values.

This is not difficult. You are both being extremely thick.

Rob van Son (Not a physicist, just an amateur) said...

"This is not difficult. You are both being extremely thick. "

Actually, you ask for the impossible. See my previous comment.

Rob van Son (Not a physicist, just an amateur) said...

"The question is whether it is physically possible for the fundamental constants to be different values than those that have been observed."

That is not an empirical question. So, how should we be able to know this. What experiment can decide this question?

And if it is not empirical, what aspects of our current theories in physics allow us to judge between these options? The value of the constants in the current theories are all ultimately determined by observation. However, you want empirical evidence for a non-empirical problem.

PS: I see ad hominem attacks as a admission that the author ran out of rational arguments.

Steven Evans said...

@Rob van Son (Not a physicist, just an amateur) said...

"Actually, you ask for the impossible. See my previous comment."

Do you know what is going on here?
There is no physical evidence currently that fundamental constants can take on other values. I am asking them for evidence rhetorically - I know they don't have any, because currently there isn't any. It's perfectly conceivable that physical evidence could be found in the future, though, supporting multiverses or fine-tuning.
So when you state that this is impossible, you are simply incorrect. You can't just make stuff up and try and pass it off as a valid opinion.

Sabine Hossenfelder said...

It's not possible. That's his point.

Steven Evans said...

@JeanTate "For HPS (History and Philosophy of Science), I prefer Lakatos to Popper, e.g. Proofs and Refutations"

Well, on here we've just spent 100 comments trying and failing to understand the difference between "theory A may not be true" and "theory A is not true".
And without a shred of evidence people are happy to claim "theory A is true". It's like Alice in Wonderland.

Steven Evans said...

@Rob van Son (Not a physicist, just an amateur) said...

"The question is whether it is physically possible for the fundamental constants to be different values than those that have been observed."

"That is not an empirical question. So, how should we be able to know this. What experiment can decide this question?"

Again, you state categorically that it is not an empirical question, but you simply don't know that. You are making stuff up again. It may be possible to observe the early universe to find out information about inflation, say, which will provide information about how the value of these fundamental constants come about and what the possible values are. It may be possible in the future to carry out physical experiments. To claim this will always be beyond empirical science is an unsupportable claim.

"PS: I see ad hominem attacks as a admission that the author ran out of rational arguments."
In lieu of an argument you cry "ad hominem". Why don't you answer some of my points? I read all your comment, and am the only person in the world who will do so, and answered your points. Then silence from you.

Steven Evans said...

Sabine Hossenfelder said...

"It's not possible. That's his point. "

It's perfectly conceivable that empirical data might be found from which it can be understood what the physically possible values of the fundamental constants are. To claim it's not possible is pure speculation.

Sabine Hossenfelder said...

It's not possible to measure values of the fundamental constants different from the values they happen to have in our universe and it's not possible to obtain any statistics of the likelihood of those other values. That's not speculation that's qua definition of what we mean by fundamental constants and our universe. Of course you can find empirical evidence that tells you the measured values in our universe must lie in certain ranges given certain assumptions about the theories.

Steven Evans said...

@ Sabine Hossenfelder

No way is currently known, but that may not always remain the case.
The fundamental constants may not ultimately turn out to be fundamental - it might be that they can be derived from a self-explanatory TOE. Also, it may be possible to make observations of the early universe which confirm a process of inflation or some universe-generating process which provides information about what the physically possible values of the constants are, even if it's not possible to empirically confirm they have been instantiated in some multiverse. What if scientists found a way of quantum fluctuating universes into existence in the lab? None of this can be ruled out .

sean s. said...

I get the sense that some refer to “fundamental values” without considering what “fundamental” means. If one does, then this matter sorts itself out.

Steven:It may be possible to observe the early universe to find out information about inflation, say, which will provide information about how the value of these fundamental constants come about and what the possible values are.

It might be possible someday to learn what values the fundamental values MIGHT HAVE HAD but in that speculative situation, those values would be known to not be fundamental; they would have been determined by something else; something ur-fundamental.

Steven:It may be possible in the future to carry out physical experiments. To claim this will always be beyond empirical science is an unsupportable claim.

True, BUT—there’s no evidence that such speculative experiments will ever be possible. Things that are NOT fundamental can be explained in terms of things that ARE fundamental; but fundamental things just are. The experiments you speculate about presume the values we think are fundamental are not actually fundamental.

Steven:It's perfectly conceivable that empirical data might be found from which it can be understood what the physically possible values of the fundamental constants are.

Again, that means these constants are not actually fundamental but determined by something else fundamental to them. The existence of such an ur-fundamental thing is pure spectulation.

If some version of a multiverse theory were correct (a really, REALLY big ‘if’) then there might be something ur-fundamental, but we have no evidence of that.

This is a variation of the “turtles all the way down” problem. Fundamental things are at the foundation of everything else. To explain them is to treat them as not fundamental.

So if you’re going to argue that these things could have had other values, you really should start by saying they’re not really fundamental.

sean s.

lukebarnes said...

Steven Evans: Your objection is answered on pages 278 to 282 of the book, under the subsection "Whence the Possibilities?"

Steven Evans said...

People who try to claim certain limits on empirical science which they can't prove tend to be either trying to rescue a role for philosophy in natural science (that's largely dead - you're not going to come up with quantum mechanics by staring at a table and thinking) or they seem to think if natural science isn't or can't be complete then it immediately follows that Jesus in the manger's papa made universes for a living. They are people without arguments but with an agenda.

Sabine Hossenfelder said...

Stevens,

No physical theory will ever be self-explanatory. Look, a situation in which you change the value of constants in our universe is not the case anyone is talking about when it comes to fine-tuning. And, sorry, but if it isn't empirically possible to confirm then it's not science.

Steven Evans said...

@Sabine Hossenfelder

"a situation in which you change the value of constants in our universe is not the case anyone is talking about when it comes to fine-tuning."
Nor am I. We are talking about whether it is physically possible for the Cosmological Constant, for example, to be (have been) other values than the observed one (whether in this universe, a different bounce cycle of this universe or another part of a multiverse, etc.). There is currently no evidence for this, despite what Luke Barnes claims. However, as physics is not a complete theory, and in particular the process by which the universe began (if it did) is not known, it cannot be ruled out that this process could be understood and even repeated in the lab. Then you would have empirical confirmation. Can this be ruled out by current physics?

"No physical theory will ever be self-explanatory."
Natural selection can be thought of as logically self-explanatory, so self-explanatory theories exist in science.
In physics, at the risk of being seen to try to teach my grandmother to suck eggs, a vast, vast number of natural phenomena have been reduced to QFT, GR and a couple of dozen constants. So why can't it be reduced further (your job, I believe), and why not ultimately to a self-explanatory theory? Can current physics rule this out?

Sabine Hossenfelder said...

Steven,

I find the discussion about what may be conceivably possible terribly uninteresting because strictly speaking you can never rule out anything. I am concerned with the current debate about fine-tuning, in which the existence of universes with other values of fundamental constants is both an unprovable and a useless postulate, hence it has no place in science.

Natural selection is not self-explanatory and neither is any other theory. They all rely on assumptions that cannot be proved true, they can merely be shown to describe observation. I gather you haven't read my book?

Steven Evans said...

lukebarnes said...

"Your objection is answered on pages 278 to 282 of the book, under the subsection "Whence the Possibilities?""

More like, whence the $322,745? Fine-tuning is a possibility, yes, but it is pure speculation and there is currently no physical information to determine the probability that it is valid. Speculating what a universe would be like if the Cosmological Constant were different to its observed value, doesn't tell one anything about whether its physically possible for the Cos. Const. to be a different value.

(1) A is True
(2) A => B is True
Therefore B is True

(1) is critical here.

Steven Evans said...

@Sabine Hossenfelder

Fine-tuning is a speculation. That's fine. The problem is people who don't understand it is pure speculation. Especially the trained physicists who don't understand that.

It was another commenter who claimed fine-tuning can *never* be an empirical question and you supported him. But that's incorrect. Because we don't even know how the universe started.

"Natural selection is not self-explanatory and neither is any other theory."
Well, it has a self-explanatory flavour to it at the level it is describing. In physics, where we are talking about the fundamentals of nature, maybe it will be possible to have a theory that exhaustively describes the starting point of the universe and in a logically self-contained way. Leaving no more questions to be asked.

Sabine Hossenfelder said...

Stevens,

Needless to say, I speak in the context of existing theories, not in the context of theories that may possibly one day exist because that's an entirely pointless discussion.

No, natural selection is not self-explanatory. If you think it is, you don't understand it. Natural selection is an example of adaptation in a complex system. It works under certain circumstances. These may or may not be fulfilled. They happen to be fulfilled on Earth and presumably other planets. The theory itself cannot explain why it applies.

I explain in my book why the idea of a theory that explains itself is nonsense.

Steven Evans said...

@sean s.

I mostly agree. Constraints of space led to sloppiness. I should have used the term "constants currently considered to be fundamental".

I have simply pointed out here that there is no physical evidence currently of fine-tuning, despite what the op claimed. Because it is not known if it is physically possible for the Cosmological Constant, for example, to be any other value than that observed. Whether these kinds of questions can be settled by empirical evidence in the future though is a whole different kettle of fish. One which, as the blog author says, is not terribly interesting or useful to speculate about at present i.e. the domain of philosophers.

Steven Evans said...

@Sabine Hossenfelder

It wasn't me who started that discussion, though. It was a philosopher claiming that fine-tuning can never be an empirically testable theory, who you agreed with. But it is simply not known whether it can be an empirically testable theory in the future or not. Is it?

By self-explanatory I mean that the idea that genes which increase the chance of survival to reproduction becoming prevalent in a species explains itself. Granted it takes place in a complex environment full of contingencies. But with physics the contingencies of 100 billion galaxies have been reduced to QFT, GR some constants and a soup of quarks. Could this be further reduced to a self-explanatory theory with zero contingencies, or at least to a point where answers can be found to the fine-tuning question? Perhaps. Unless the explanation in your book rules that out categorically?

JeanTate said...

John Bahcall wrote a paper or two on an astrophysical test of the constancy of the fine structure constant (which may or may not be a fundamental constant, YMMV), for example here: https://arxiv.org/abs/astro-ph/0301507

There is, or was, at least one group doing something similar, using the “Many Mutiplet method”. Bahcall et al. found alpha to be constant, within the uncertainties; the others found varying levels of inconstancy, but the community appears to have not accepted these results (partly due, no doubt, to the fact that the results themselves are not consistent, a bit like the DAMA/LIBRE Dark Matter search results).

Some fundamental constants get tested, indirectly, through for example recent MMX-type experiments, or astrophysical tests of Lorenz violations.

I do not know how these, and similar, figure in to Steven Evans’ quest.

sean s. said...

Steven,

By self-explanatory I mean that the idea that genes which increase the chance of survival to reproduction becoming prevalent in a species explains itself.

Imagine going back to 1850 and expressing that idea to a leading biologist; they would need a LOT of explanation, and not only about what some of the words mean (“Gene?” What is that?)

You’d have to explain how inheritance works, the statistical analysis that justified Mendel’s conclusions, etc.

Theories (which are explanations) only become “self-explanatory” after a lot of explanation and some familiarity.

A new theory could only be “self-explanatory” to someone who’s familiar with the topic; and even then, they may need a lot of further explanation.

sean s.

Steven Evans said...

@ JeanTate @ sean s.
My point here, a completely obvious one, was simply that fine-tuning is not physics, it's pure speculation. There is no evidence whatsoever that fine-tuning is physics. Discussion on whether fine-tuning will be empirically testable in the future will probably turn out to be fruitless at this juncture. I'm mistaken about the "self-explanatory" nature of natural selection: a gene being selected has been shown to be tautologous with a gene increasing chances of survival, that's all.

sean s. said...

Steven: “... a gene being selected has been shown to be tautologous with a gene increasing chances of survival, that's all

I think you’re using the word “tautologous” incorrectly here. Tautologies are propositional redundancies; your example is not redundant. Gene selection is caused when genes increase the chances of survival. It might seem redundant now, but only because we are familiar with it and now it seems obvious.

Were there references to “survival of the fittest” prior to Darwin, Wallace, and Spencer? If not, then it could hardly be “tautologous”.

sean s.

Steven Evans said...

@sean s.

The OP claimed that fine-tuning is physics. There is no evidence that it is anything but pure speculation. Someone else claimed that fine-tuning can never be empirically tested, but that's also speculation as physics is not a complete theory. That's what was being discussed, although even that was a tangent as "Lost in Math" was supposed to be the topic of discussion.