Various

  • A few months ago I ended up doing a little history of science research, trying to track down the details of the story of the Physical Review’s 1973 policy discouraging articles on “Foundations”. The results of that research are in this posting, where I found this explanation from the Physical Review editor (Goudsmit) of the problem they were trying to deal with:

    The event [referring to a difficult refereeing problem] shows again clearly the necessity of rapid rejections of questionable papers in vague borderline areas. There is a class of long theoretical papers which deal with problems of interpretation of quantum and relativistic phenomena. Most of them are terribly boring and belong to the category of which Pauli said, “It is not even wrong”. Many of them are wrong. A few of the wrong ones turn out to be valuable and interesting because they throw a brighter light on the correct understanding of the problem. I have earlier expressed my strong opinion that most of these papers don’t belong in the Physical Review but in journals specializing in the philosophy and fundamental concepts of physics.

    I had heard that people studying foundations of quantum mechanics, frustrated by this policy, had started up during the 1970s their own samizdat publication, called “Epistemological Letters”. I tried to see if there was any way to read the articles that appeared in that form, but it looked like the only way to do this would be to go visit one or two archives that might have some copies. Unbeknownst to me, around the same time Notre Dame University had just finished a project of scanning all issues of Epistemological Letters and putting them online. They are now available here, with an article about them here and an introductory essay here.

  • There’s an interesting essay on the arXiv about the current state of BSM physics, by HEP theorist Goran Senjanović, entitled Natural Philosophy versus Philosophy of Naturalness.
  • Here’s an article about problems string theorist Amer Iqbal has been having in Pakistan.
  • The New York Times has an article about Cedric Villani and his campaign for mayor of Paris. The election is next month, and I’m having a hard time figuring out why Villani is running. There doesn’t seem to be a lot of difference in policy views between the current mayor (Hidalgo) and the Macronistas (Griveaux and Villani), with the main effect of Villani entering the race a splitting of the Macron party vote.
  • I was sorry to hear recently about the death of mathematician Louis Nirenberg. Kenneth Chang at the New York Times has written an excellent obituary. Terry Tao has some comments here.

Update: Excellent rant on Twitter from Philip Ball about misrepresentations of the Copenhagen interpretation. For your own rants, please engage in them on Twitter rather than here.

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19 Responses to Various

  1. Akhil says:

    Peter,
    Do you have anything to disagree with Goran Senjanović paper?

  2. Peter Woit says:

    Akhil,

    I mostly agree with the paper. As Senjanović points out, the problems with SUSY models/GUTs/naturalness were all known pre-LHC. It’s interesting to see that the LHC results are now causing people to recognize these problems.

    I agree with him that the neutrino sector of the SM is now the part where there are mysteries that experiments might soon shed light on. I disagree about left/right symmetry, the left/right asymmetry I think is a fundamental feature of space-time.

  3. Peter Woit says:

    By the way, I just noticed that the new issue of Symmetry is out, with first article “Fine-tuning versus naturalness” that starts with the sentence:

    “When physicists saw the Higgs boson for the first time in 2012, they observed its mass to be very small: 125 billion electronvolts, or 125 GeV.”

    Note that there’s something obviously very peculiar about this. Since 125 GeV is higher mass than any other state known except the top quark, an equally good first sentence would have been:

    “When physicists saw the Higgs boson for the first time in 2012, they observed its mass to be very large: 125 billion electronvolts, or 125 GeV.”

    What the author doing is assuming that the right way to measure masses is in terms of a GUT scale (there is no evidence at all for GUTs), or the Planck scale supposed to be relevant to quantum gravity (we don’t know what quantum gravity is).

  4. Janko Frazzle says:

    I’m disappointed with Cedric Villani, he should know better. To be a great mathematician you need to have an interest in the subject from early childhood, and the same is with politics.

  5. Peter Woit says:

    Janko Frazzle,
    The French have in the past had political leaders who were first-rate mathematicians (e.g. Paul Painlevé). As for Villani, if you read his memoir you’ll see that he consciously set out to win a Fields Medal, and successfully did so. With that track record, I wouldn’t discount his prospects for achieving whatever his next goal is.

  6. Peter Shor says:

    It seems to me that the comment

    “Most of them are terribly boring and belong to the category of which Pauli said, “It is not even wrong”. Many of them are wrong.

    probably was true. Quantum foundations is a very attractive area for cranks, most of whose papers would be wrong or “not even wrong”. On the other hand, throwing out all these papers, even those by lesser-known bona fide physicists¹, seems to me to be a mistake on the order of a math journal saying that, because they have been deluged by a flood of incorrect papers proving the Riemann hypothesis, that they will reject all such papers without even looking at them.

    On the other hand, most of the cranks probably didn’t even known that Epistemological Letters existed, effectively pre-screening submissions to it.

    ¹ Surely they wouldn’t have rejected a foundations paper by Feynman without looking at it first.

  7. Peter Woit says:

    Peter Shor,
    When I looked into the actual story, see
    https://www.math.columbia.edu/~woit/wordpress/?p=11263
    I found that it was just not true that Phys Rev had a “no foundations” policy. The supposed “no foundations” policy was announced here
    https://journals.aps.org/prd/pdf/10.1103/PhysRevD.8.357
    which starts off with explaining the reason for the policy:
    “We occasionally receive a manuscript for which it is extremely difficult and sometimes impossible to find a suitable referee who is willing to read it.”
    This clearly would not a apply to a paper from Feynman…

    Goudsmit later gave a specific example of why they instituted the policy, this paper:
    https://journals.aps.org/prd/abstract/10.1103/PhysRevD.8.1679
    In his archives you can find a long discussion of the difficulties they had trying to get this paper properly refereed.

  8. Suomynona says:

    Peter Shor,
    My understanding of Feynman’s work is that he was uninterested in epistemological issues, so it’s unlikely he would have submitted something which violated the policy anyway.

    Another note on Goudsmit is that he also had a similar policy on the other end of the spectrum, for papers perceived as too much about technological or engineering developments. Apparently some of the foundational papers developing the physics of the laser were rejected without review as the author described their work as on the “optical maser” (at the time, masers were widespread laboratory instruments).

  9. Felipe Pait says:

    Part of the reason why Villani is running may be that he can. The election in Paris is in 2 rounds, which means that a candidate that doesn’t win can 1) gain name recognition; 2) bargain support in the 2nd round; and 3) not be tainted as a spoiler for splitting the vote.

    It is somewhat like a primary in the US, full of candidates that can at most hope to get a spot as vice president or in the next round of elections.

  10. Peter Shor says:

    Suomynoma: Actually, Feynman was interested in epistemological issues (he was interested in everything); I assume he never published anything about it because he never figured out anything interesting and new to say about them.

    When I was at Caltech as an undergrad, Feynman gave a talk where he explained that he had looked at Bell’s theorem, trying to find hidden hypotheses. The hidden hypothesis he identified was that all probabilities had to be between 0 and 1, so he was trying to figure out whether negative probabilities could get around Bell’s theorem.

    He later published a paper about negative probabilities, but it didn’t solve the difficulty with local hidden variable theories, and his motivation for looking at the question was only mentioned very briefly in it.

  11. Blake Stacey says:

    An interesting discovery from looking into the history last September was that Goudsmit actually declared a subject non grata three times in its first decade of PRL: masers in 1959, the Mössbauer effect in 1960 and gauge theories in 1965. In all these cases, the motivation was that too many mediocre, trend-following papers were being received, and so new ones would only be considered if they stuck to a high standard of concreteness. The bit of lore that they rejected the first article on lasers because they thought it was just another maser paper might or might not be true.

  12. Anon says:

    Hi Peter — The observed light neutrino masses (m_nu) suggest a heavy right handed neutrino mass scale ~ v_weak^2/m_nu which works out to be about 10^14 GeV when we put in v_weak~200 GeV, m_nu = 0.5 eV.

    The above is simple dimension analysis — we can get large mass scale from two mass scales, and the physical reasoning behind this is the well known seesaw mechanism. Now 10^14 GeV is beyond reach of colliders. So if we want the large mass or new physics scale to understand the origin of neutrino masses to be at the TeV scale we need to multiply 10^14 GeV by a dimensionless small number ~10^{-11}. Such a small prefactor can physically be there if the Dirac type Yukawa couplings of the neutrinos are ~ sqrt{10^{-11}} = 10^{-5.5}.

    Now we can argue that there is no reason why such a small prefactor cant be there in nature and search for the physics of the seesaw mechanism (right handed currents, neutrinos etc) at the TeV scale. But really is this physics more likely to be there at the LHC or even the next collider or is this physics more likely to be at 10^{14}GeV?

    Naturalness arguments have generally worked and therefore the faith that multiplying by a small prefactor and getting the answer we want (namely reachable by LHC) is not likely to pay big dividends.

    The Higgs mass seems to be fine-tuned and naturalness arguments appear to not work in this case, but naturalness is still a very useful guide (in experience of science over generations it usually works) and if the neutrino mass physics is indeed at 10^14 GeV then better to start thinking of what experiments can provide evidence for something at that scale (it could be other precision tests) rather than only working on LHC/TeV scale physics for right handed or B-L breaking scale.

    Of course those guided by the idea that it is best to work at the TeV scale would also be doing great work because maybe there is a prefactor of 10^{-11} in the above. LHC or the next collider may help prove there isn’t (most probable outcome aka nightmare scenario) or if it is there there that would be a remarkable discovery.

    I dont see why people cant purse both approaches — or as a community we cant pursue both — trying to find BSM physics at TeV scale though there is no real reason or natural reason to expect one, as well as think of innovative ways to probe our theories even if their mass scale is out of reach of the LHC and conceivable future colliders.

  13. Peter Woit says:

    Anon,

    The argument against usual Dirac mass-terms for neutrinos is that the ratio of electroweak scale to neutrino mass would then be unexpectedly large (“unnatural”). But we already know that the ratio of electroweak scale to the electron mass is very large (like 400,000). To me this just makes the point that we don’t have any idea where the Yukawas come from, and not only no good reason to expect them to be order one, but plenty of evidence that there’s an an unknown reason for them to be very small. I understand the usual seesaw argument, I just don’t think it’s all that strong an argument for a new physics mass-scale.

    My earlier comment about possible new results about neutrinos was mainly a reference to non-collider experiments (neutrinoless double beta decay, sterile neutrinos). The speculative idea of a new high mass scale to explain neutrino masses doesn’t affect my later comment that saying the Higgs mass is “small” makes no sense, since you should be comparing it to scales you know exist, not speculative ones.

  14. Amitabh Lath says:

    I never thought of naturalness as anything more than handwaving guesses. Sort of like Enrico Fermi’s guess at the number of piano tuners in Chicago. Imagine if after Fermi made the guess they walked around looking for piano tuners and didn’t find any. Maybe there is something suppressing piano tuners. Maybe they can’t afford to live in Hyde Park and all moved to Englewood. Maybe people prefer woodwinds and gave up piano. Or maybe the piano tuners are there but you can’t see them because they look like normal people.

    Goran Senjanović’s assertion that naturalness is some deep philosophical choice seems too harsh. Naturalness is what you do when you don’t really have any other way.

    Also, the bit about LHC experiments having a SUSY group and separate exotica group is true, but it’s not because of we think SUSY is somehow better than. Essentially we sort physics signatures that have large missing momenta (MET) into the SUSY group, and everything else into the exotica group. I work on R-parity violating SUSY and that’s in the exotica group because no MET.

  15. Anon says:

    Well we do know that the charged lepton Yukawa couplings of tau, mu and electron are similar to the bottom, strange and down quarks’ Yukawa couplings. That is a good reason to expect the Dirac Yukawa couplings of nu_tau, nu_mu, nu_e to be similar to top, charm and up quarks’ Yukawa couplings respectively.

    Of course, it is not a proof but is a strong motivation to do further research with this thinking.

    One can also, of course, assume as you seem to prefer, that the Dirac Yukawas of all three neutrinos are very very small and the light neutrino masses are all Dirac type, and nature has an exact B-L symmetry that prevents the Majorana mass term in the SM with the addition of 3 right-handed neutrinos.

  16. Goran says:

    Some comments on the comments on my essay. When I give an example of the LR symmetric theory, claiming it is a self-contained, predictive model of the origin of neutrino mass (analog to Higgs-Weinberg mechanism for charged fermion masses), I do not want to convince the reader of my starting point, I am only asking her or him (read Peter in this case 🙂 to appreciate the structural correlations that follow unambiguously. Moreover, it was the LR theory that led originally to neutrino mass long before experiment (many were telling me in the seventies that I was wasting my time – neutrino was supposed to be massless to most).

    All I am doing in my essay is to advocate that high energy physics goes back to being natural philosophy in the Newton’s sense of the world. You may be as philosophical as you wish, but you must make predictions and let the experiment decide, period. Which is why I argue against the obsession with naturalness as the main guiding principle for the BSM physics. Simply, it failed to produce an analog self-contained framework with verifiable predictions, and instead became a never ending game whose rules can change as and when one wishes.

  17. Goran says:

    Regarding the scale of seesaw. Seesaw by itself is just a scenario which basically says nothing – you are supposed to accept that a particle at unreachable energies ‘explains’ the smallness of neutrino mass? I argued, albeit briefly (I cite relevant papers for in-depth analysis) that a way to new physics and information about its scale ought to come through a well defined theory and experiment. In this case it is neutrinoless double beta decay which may be caused by neutrino Majorana mass or new physics behind it (or both). If the former explanation fails, say because we learn meanwhile that the hierarchy is normal, or even better, if electrons coming out were say RH, then we would need new physics. Simple dimensional analysis tells you then new physics must lie at energies not far from the LHC – and in the LR theory it is really hard to go above the 6 TeV LHC reach for the mass of the RH gauge boson. In other words, it is experiment and not wishful thinking that should (and can) decide the whether or not there is a small coupling in the Weinberg operator. Btw, the small coupling is rather natural in the LR theory where neutrino and electron live together – the 10^{14} GeV cut-off requires neutrino Dirac mass on the order of the top quark mass.

    This said, if neutrino hierarchy ends up being inverse, or better, if you saw the neutrinoless double beta decay with LH electrons, I for one would, admittedly sadly, be first to admit no reason for new physics behind neutrino mass at reachable energies.

  18. Kris Krogh says:

    Peter,

    I would guess you’ve never read John Bell’s book, Speakable and Unspeakable in Quantum Mechanics, published in 1987. It’s a compilation of his papers on quantum mechanics, each of them remarkably insightful. The majority were never published in mainstream journals, and several are from Epistemological Letters. That was definitely a reflection of the politics faced by Bell and his collaborators, as suggested by the book’s title. Although the publishing situation is different now, those politics are still not behind us.

  19. Peter Woit says:

    Kris Krogh,
    I have looked at that book, and read some of the articles in it. From what I remember I was put off by Bell’s fondness for Bohm/hidden variables, and didn’t find what I was reading helpful in terms of providing any insight into what seems to me the main problem (emergence of the classical from quantum).

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