The “Unnatural” Standard Model

The Standard Model is a physical theory of a spectacularly successful sort. It is built on beautiful and deep mathematics, covers almost all known physical phenomena, and agrees precisely with the result of every single experiment ever done to test it. It leaves open a very small number of questions: why this specific combination of small symmetry groups and their representations? What determines the parameters of the model (18 if you ignore neutrino masses, 7 more if you include them)? What about gravity? Does it need to be extended to account for dark matter?

For several decades now, there has been a very active and heavily advertised field of “Beyond Standard Model” physics, the study of extensions of the standard model that remain consistent with experimental bounds. While BSM models have played a role in guiding experimentalists towards things to look for that are not already ruled out by what is known, they have never come anywhere near fulfilling the hope that they might provide some insight into the SM itself. They provide no explanation of the unexplained aspects of the Standard Model, instead adding a great deal of additional unexplained structure. Perhaps the simplest and most widely studied example is the minimal supersymmetric extension of the SM, which not only explains none of the 25 undetermined SM parameters, but adds more than 100 additional such parameters to the list.

Theorists have traditionally followed what has been described as “Albert Einstein’s dream that the laws of nature are sublimely beautiful, inevitable and self-contained”, and the SM is our closest approach so far to Einstein’s dream. If you shared this dream, the known BSM models would never have much appealed to you, since they just added complexity and extra unexplained parameters. You also would not have been at all surprised by the strong negative results about such models that are one of the two major achievements so far of the LHC (the other is the Higgs discovery). If you’re a follower of Einstein’s dream, the obvious reaction to the LHC results so far would be to rejoice in the vindication of this dream, welcome the triumph of the simplicity of the SM, and hope that further study of the Higgs sector will somehow provide a hint of a better idea about where the SM parameters come from (almost all of them are Higgs couplings).

Remarkably, a very different story is being sold to the public by those who had a great deal invested in now failed BSM models. In this story, the BSM models were the ones of Einstein’s dream: they were “natural”, and their failure leaves us with the “unnatural” Standard Model.

An article entitled Is Nature Unnatural? is the source of the above quote about Einstein, and it tells us that

Decades of confounding experiments have physicists considering a startling possibility: The universe might not make sense…

In peril is the notion of “naturalness,” Albert Einstein’s dream that the laws of nature are sublimely beautiful, inevitable and self-contained. Without it, physicists face the harsh prospect that those laws are just an arbitrary, messy outcome of random fluctuations in the fabric of space and time…

“The universe is impossible,” said Nima Arkani-Hamed, 41, of the Institute for Advanced Study, during a recent talk at Columbia University [more about this talk here].

What is behind this sort of claim that down is up is abuse of the English word “naturalness”, which in this particular case has been adopted by theorists to refer a technical property better described as “not quadratically sensitive to the cut-off scale”. There’s a lot to be said (and a lot that has been said on this blog) about the precise technical issue here. It’s a real one, and likely an important hint about the true nature of the Higgs sector of the SM and where all those undetermined parameters come from. Getting rid though of this technical problem by invoking hundreds of new undetermined parameters is not the sort of thing Einstein was dreaming about. He would see the LHC results as vindication and encouragement: as we investigate new energy scales we find the universe to be as simple as possible. It’s remarkable to see this great discovery being promoted as telling us that we have to give up on Einstein’s dream and adopt a pseudo-scientific research program based on the idea that physical “laws are just an arbitrary, messy outcome of random fluctuations in the fabric of space and time”.

Update: The Science News story has now appeared at Scientific American, with the title New Physics Complications Lend Support to Multiverse Hypothesis. The “New Physics Complications” are the LHC only seeing pure SM behavior. If the LHC had seen a complicated SUSY spectrum, that would have been “natural”, but somehow seeing the simplest possibility has become a new “Complication”. It is a “complication”, but a sociological not physics one. SUSY theorists do have an answer for the complication of their ideas failing: the Multiverse did it.

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58 Responses to The “Unnatural” Standard Model

  1. Bernhard says:

    I agree this “The universe might not make sense…” or ““The universe is impossible,” thing from Arkani-Hamed is complete BS and has to do, to some degree, with frustration the BSM theory community (with Arkani-Hamed being the king of it) feels about the fact that the whole BSM businesses have not yet gone anywhere.

    But I think it is unfair to say ” They provide no explanation of the unexplained aspects of the Standard Model”. There are interesting BSM models that do explain things like strong CP problem, neutrino masses,quark-lepton family replication, etc in a quite conservative way and not adding too many parameters. There is really no way out, unless you are the Standard Model anything beyond it will have to add something, at least one new particle necessarily. None of those models have worked so far, but this might still change.

    One does not need to depreciate BSM physics to appreciate how spectacular the SM is. That the desperation led some people to do pseudo-science is a problem, but other people in the community tried to stick with the rules of the game.

  2. King Ray says:

    I think the things that made Einstein successful were his imagination, dogged determination and his sense of beauty and simplicity (his ‘nose,’ as he called it). BSM physicists on the whole seem to not use simplicity as a metric at all. You have to explain more things than you add to make things simpler.

  3. Igor Khavkine says:

    I’d like to second Tom’s question from a comment to Peter’s preceding post: What is the track record of naturalness? More precisely, when have considerations of naturalness correctly suggested the existence of previously unseen degrees of freedom, together with reasonable constraints on them, prior to their actual observation? The examples need not be restricted to high energy physics.

  4. MathPhys says:

    The technical problem of quadratic dependence on the UV cut-off probably tells us something about the techniques that we use to compute radiative corrections, rather than the physical observables that we wish to compute.

  5. X says:

    Ignoring neutrino masses was never a good idea, and now that most of the parameters measured to fair precision, it’s absurd to class them differently from the rest of the SM parameters. Maybe you could class Theta differently, but that might be a stretch for the standard Standard Model.

  6. Anonyrat says:

    Without “naturalness” the ideology of the standard model as an effective QFT evaporates. Irrelevant operators could have arbitrarily large coefficients enough to overcome the suppression by powers of the cutoff scale.

  7. Ben says:

    @Igor,

    Arkani-Hamed himself goes into a couple of interesting historical examples of the success of naturalness arguments in a video Peter posted back in December; http://www.math.columbia.edu/~woit/wordpress/?p=5416. (link straight to video: http://online.kitp.ucsb.edu/online/higgs_m12/arkanihamed/)

    If you skip to 16.40 he starts talking about the classical electron self-energy, the mass splitting between the charged and neutral pions, and very briefly mentions k-kbar mixing, though he actually starts talking about naturalness around 13.00.

  8. fuzzy says:

    hi peter,

    i agree on the general statements, but not completely on the formulation of SM you gave. the gauge principle (and renormalizability) instructs you to write all the legitimate operators, not only those you like to include.

    in the light of this principle, the SM as a gauge theory has also the theta term and the constant of the potential (cosmological). once you introduce right handed neutrinos, you do not have 7 parameters but much more.

    furthermore, when you make the statement concerning “100 more parameters”, you write BSM but you mean MSSM (SUSY). no problem to admit that MSSM is (was?) a very popular branch of BSM, but as a scientific concept, BSM is a much wider thing than MSSM: we better avoid confusion.

    actually, i do not think it is wise to speak acrytically of BSM; we should speak of more specific things, to avoid falling again on metaphysics.

    thanks!

    ps i have only one question concerning the quotation: it is quite evident that the star is the chap who succeeded to explain us so clearly that “the universe is impossible,” (douglas adams would be proud of him) but who is this einstein? maybe the idea was to write weinstein, and a “w” is slipped away

  9. francis says:

    Actually, there exist theories compatible with Einstein’s dream.
    For example, Connes’ ncg model gives a conceptual explanation of the SM, reduces the number of free parameters and is compatible with experiment.

    So IMO the hope of fulfilling Einstein’s dream should not be abandoned but should be an indication to know if we are on the right track or not…

  10. Peter Woit says:

    fuzzy,

    I pretty much agree with your comments, to make the point I wanted to make I didn’t include many details which aren’t relevant to the point.

    There’s very little one can sensibly say about all BSM models, the reason for concentrating on the MSSM is that it’s the one that is most well-defined and well-studied. For instance, once one starts in with things like large extra dimensions, I have no idea how to characterize the size of the theory space one is invoking, other than that one has moved away from something highly constrained to something much, much larger.

  11. Toni says:

    Peter,

    your last statement implies that you dislike emergence. Are you really stating that emergence is nonsense? And this despite the old argument that general relativity is a result of the thermodynamics of spacetime?

  12. Peter Woit says:

    Toni,

    “Emergence” is just a word. I’ve no strong opinion about what the right fundamental variables are to describe gravitational degrees of freedom: maybe the metric is not fundamental, but “emergent”. But that’s a pretty empty idea unless you have some serious proposal about what really is fundamental, and what the relation is to the SM (where we do know exactly what the fundamental degrees of freedom are).

  13. fuzzy says:

    hi peter, thanks, but if we agree, then why to jump from MSSM to large xdim (of nima, gia and savas–again!) rather than remarking that the class of BSM theories that take care of neutrino masses have generally much less parameters, and they usually have firmer reasons of being called BSM?

    moreover, i would like to insist on the old good gauge theories; they are not yet sufficiently explored! even the simple left right models — but this is true also for so(10) — need to be taken much more seriously than it was done till now.

    in my view, rather than drawing rash conclusions, we need some time to think and critical attitude: i feel that the story of naturalness should have taught us that groupthink is not the way to explore the nature.

  14. Marcel van Velzen says:

    Recommended! Guido Altarelli presents an excellent, honest and balanced overview of the current state of naturalness here:

    http://indico.cern.ch/getFile.py/access?contribId=27&sessionId=3&resId=0&materialId=slides&confId=239571

  15. imho says:

    From a cond matt theorist’s perspective this is a pretty clear example of the limits of human understanding. In the absence of experiment, it seems progress grinds to a halt and science morphs into Philosophy with a mathematical cloak.

    How did you guys and gals end up here? Why do so many unquestionably accept, what seems to me to be, unproven assumptions. Who determined that quantizing gravity is any more sensible than quantizing Navier-Stokes? Who decided that dimensional analysis should be used to define a Planck Length? Please explain to me why so many are completely certain that the only two options are multiverse or super symmetry… especially since we know absolutely nothing about 96% of the “stuff” in this universe? This whole thing smells like religions group think.

    I’m on your team and I’m really struggling to see the value here. The funding agencies need to continue, and perhaps accelerate, the de-emphasis of unification research. There really shouldn’t be more than a few dozen people in the US doing this kind of thing.

  16. Matt says:

    Okay, so now condensed-matter theorists are calling for other physicists’ funding to be cut. That’s exactly the kind of counterproductive feuding among scientists that doomed the SSC and eventually all high-energy experimental physics in the US altogether. Bravo!

    Peter, I think this original post of yours is an incredibly important one, because I think it crystallizes (intentionally or unintentionally) a lot of your thinking on fundamental physics today.

    I’ve been following your opinions on physics for a long time now, and what started as (justifiable) skepticism of string theory has morphed into a general bitterness toward essentially everything going on in high-energy theory today, string theory or not. It’s become what I once heard called “sidewalk supervising.” That’s folks who stand on the opposite sidewalk shouting criticisms at the construction workers trying to repair a building. You’ve gone from being unhappy with one particular model of new physics (string theory) to complaining about essentially everything that tries to go beyond the Standard Model, regardless of the approach.

    And yet, I have no idea what specifically you’d prefer be done instead. You seem to think that working on fundamental physics is something worthwhile to do, but apart from saying vaguely that you think more attention needs to be paid to chiral gauge symmetries (because you believe there’s apparently something very deep about the fact that the internal gauge symmetries of the Standard Model know about leftness and rightness, even though it’s trivial to think up simple models for which this is totally un-meaningful), there isn’t much you’ve suggested.

    In this post of yours, I think you make clear some of your motivations.

    You write that “The Standard Model is a physical theory of a spectacularly successful sort.” You also say that it “covers almost all known physical phenomena, and agrees precisely with the result of every single experiment ever done to test it.”

    Sure. But, as you well know, the Standard Model, like all realistic quantum field theories that actually describe practical physics, also predicts that it has a limited regime of validity. So its success and agreement with experiment in that regime of validity does not tell us that it should be valid outside that regime.

    You say “It is built on beautiful and deep mathematics,” but you know that’s irrelevant. There is no metaphysical reason Nature should care about mathematical beauty at a fundamental level. Beauty may have been a nice guide to helping us guess way in advance that QFT should be the right description for low-energy physics, but you know that it cannot be a fundamental justification. Every argument originally inspired by beauty, from Dirac’s argument for his eponymous equation to Einstein’s argument for general relativity, has now been put on a better footing in terms of actual physical principles. We now have independent reasons for believing all those ideas — beauty may have gotten our foot in the door, but many, many beautiful ideas are wrong, and plenty of un-beautiful ideas are sometimes right.

    There are very general arguments that physics consistent with locality, relativity, and quantum mechanics should look like a “beautiful” effective field theory at low energies. Maybe you find such arguments ugly or less inspirational, but inevitability is a far more important criterion than beauty for understanding the Why? of physics.

    Einstein’s theory of gravity is “more beautiful” and has “fewer adjustable parameters” without a cosmological constant or higher-dimension operators, but there’s no physical argument they should be there — and lots of arguments that both the cosmological constant should be there (and experimental confirmation of said fact) as well as that higher-dimension operators should be present suppressed by large mass scales and thus very difficult to detect. And we already have models now in which the beautiful spacetime of general relativity is only an emergent approximation of altogether different physics, and that’s an important proof of principle.

    But, more importantly, the Standard Model isn’t just incomplete in the sense that it predicts its own eventual demise at sufficiently high energies or doesn’t explain many of its adjustable parameters or gauge groups. As you note yourself later in your post, the Standard Model doesn’t account for a staggering 95% of the mass-energy in the universe whose existence we know from experiments and observations. Nor does it accommodate gravity at arbitrarily high energies in a manner fully consistent with quantum mechanics.

    You go on to attack essentially all the BSM models. But people aren’t proposing those models just because they are madly in love with, say, split supersymmetry of all things. There has to be physics beyond the Standard Model, and any physics beyond the Standard Model is, by definition, BSM. But the Standard Model, and, more generally, principles like relativity and quantum mechanics (which include conditions like unitarity, causality, etc.), put tremendous constraints on the allowed models one can propose. (And bounds on the validity of relativity and quantum mechanics are extremely small today, due to painstaking work by lots of people over decades.)

    The people working on BSM physics are therefore operating under a very tight straightjacket. It’s not easy work, and coming up with an idea that is consistent with everything we already know is very, very difficult. The vast, vast majority of ideas (“beautiful” in their mathematics or not) are simply ruled out. You may not like some of the ideas that are still in the running, but they’ve made it through a grueling gauntlet. They’re favored because they’ve managed to jump through a million hoops. That was, after all, one of the reason people got so excited about string-inspired ideas in quantum gravity.

    It’s sort of like folks who think the idea of WIMPs as dark matter is an ugly idea, and would prefer, I don’t know, modifying general relativity. Well, that just doesn’t really work. People have expended a huge amount of energy on that, and it just doesn’t work very well in a manner consistent with all the observations we already have and consistency with other physical principles we have exceptionally-strong bounds on.

    If you think you have better ideas, then please join the fray! I know it’s a cliche, but Roosevelt was right about how it’s far more admirable to be a contender, to be getting one’s hands dirty, than to be yelling criticisms from the stands that the contenders aren’t doing it right. Unless you think physicists should simply stop trying to do fundamental physics, there is no alternative to what’s going on. They’re not doing BSM in ways you don’t like just to piss you off — these are the only directions that have been found so far that are consistent. If you think you have a better approach, please go for it.

    Because the only real alternative to trying to thread this million-dimensional needle is just to stop trying to do new high-energy theoretical physics altogether. Maybe there are people who think that’s better. But pursuing fundamental physics, trying to resolve paradoxes, and trying to make seemingly inconsistent ideas work together properly has historically yielded helpful results, even if only to other fields.

    Einstein was originally trying to reconcile a purely theoretical problem at the time he was trying to make gravitation consistent with relativity. If there had been no planet Mercury or a moon whose angular size in Earth’s sky was the same as the sun, then experimental confirmation of his theory might well have taken decades. General relativity has been tremendously helpful to our understanding of lots and lots of physics and mathematics. We understand QFT far better because of many of the tools of general relativity.

    Hawking was trying to resolve paradoxes when he ended up deriving black-hole radiation and black-hole thermodynamics, which now provide very strong constraints on proposed new physics and may give us another hint on how to proceed. We’ve learned a great deal about QFT in curved spacetime, and about phenomena like the Unruh effect, as a consequence.

    Going back even further, we can look at the though-experiment paradoxes that presaged quantum mechanics, or Maxwell’s corrections to Ampere’s law that fixed up his now-eponymous equations that then led to prediction of electromagnetic radiation.

    Even inflationary cosmology, which has generated actual predictions that have held up remarkably well, started out as (yes!) an attempt to solve various paradoxes with naturalness that arise in the old Big Bang model. (The horizon problem, the relic problem, the flatness problem — all are naturalness problems!)

    There’s a long history to show that pursuing fundamental theoretical physics for its own sake, like any kind of basic research, yields unexpected fruit, although most of the attempts end up not working. But to stop it all because of those mostly wrong directions would have been a disaster to all further progress.

    Even supersymmetry and string theory have been immensely helpful in understanding QFT. Just as classical mechanics makes a lot more sense in light of quantum mechanics, and QFT sheds a lot of light on quantum mechanics, so too do ideas like supersymmetry and string theory teach us a lot about QFT. Supersymmetry has given us entirely new ways of understanding qualitative features that are otherwise intractable in simpler QFTs, confinement being a prominent example. And string theory has provided many new ways of understanding familiar QFTs as well; indeed, many realizations of string theory are now known to be dual to certain QFTs, so that the two subjects aren’t as different as we once though they were. Collider physicists are literally using results originally from string theory to do far better calculations of actual events in their accelerators.

    I don’t know what else to say except that we have two options — either shut it all down, or do the hard work of trying to thread the needle in the ways allowed by what we already know and keep working until we finally stumble on the right answer.

    What else do you propose? And please be specific!

  17. Bob Jones says:

    Many readers of this blog would benefit from reading this article:

    http://arstechnica.com/science/2013/05/earning-a-phd-by-studying-a-theory-that-we-know-is-wrong/

  18. Mario says:

    @Marcel van Velzen: I cannot agree. Altarell’ does not account for the conformal standard model and consider seriously anthropic ideas. I think that after this paper http://prl.aps.org/abstract/PRL/v110/i15/e151601 this approach should be considered a serious and viable way out to the question of naturalness.

  19. Marcel van Velzen says:

    @Matt,

    Nice piece! There’s a lot of truth in it. People should continue to work on BSM physics but should also realize what they are up against and don’t make misguiding claims because it’s here that the problem begins. To be specific:
    “Hawking was trying to resolve paradoxes when he ended up deriving black-hole radiation and black-hole thermodynamics, which now provide very strong constraints on proposed new physics and may give us another hint on how to proceed. We’ve learned a great deal about QFT in curved spacetime, and about phenomena like the Unruh effect, as a consequence.”

    Although the mathematics is really nice and convincing Hawking radiation and the Unruh effect have never been observed so it should be that MAYBE we’ve learned a great deal about QFT in curved spacetime and to say that they provide very strong constraints on proposed new physics is also unclear and the hint they give us to proceed may be totally wrong. An exploding black hole has still to be found.

  20. Igor Khavkine says:

    @Matt, what you’ve written about keeping theories that have passed stringent empirical tests, be they “ugly” or “beautiful”, is great and I agree with that wholeheartedly. But, some of the motivations that you list for going beyond the Standard Model are just wrong. I mean “wrong” in the sense that they are based on very shaky arguments. These include: (a) the Standard Model is internally inconsistent in some regime, (b) taking GR together with the Standard Model is inconsistent with quantum mechanics, (c) that hierarchy is a problem (or more generally that measured values of free Lagrangian parameters require an “explanation”), (d) that black hole entropy requires a statistical explanation. In the same breath, you’ve also pointed out real problems that do need to be solved for us to have a better working model of the universe: (a’) dark matter is not included in SM + GR, (b’) whatever quantum field that seeded primordial fluctuations (say “the inflaton”) is not included in SM + GR.

    To be fair, you didn’t actually say (d), but that is what commonly stands behind the code phrase that “the Hawking effect gives us a hint about quantum gravity”. Also, certainly, my opinion will likely not align 100% with Peter’s, but since you asked for some specific suggestions, here are some. What not to do: try to solve problems (a’) and (b’) where there is actual data available to constrain possibilities by simultaneously trying to solve (a), (b), (c) and (d). The latter four are red herrings that prompt people to take uncontrolled flights of fancy into theory space. And it is these flights of fancy I believe attract most criticism, like Peter’s. What to do: try to solve problems (a’) and (b’) by starting with SM + GR and using conservative effective field theory methods, constrained by the available data, to nail down the quantum numbers and interactions of the dark matter and inflaton fields. Actually, from what I’ve seen, there are some hard working cosmologists and particle theorists doing exactly that. So, your challenge of putting these guidelines in practice, is already being met, albeit by what it seems like a minority in these fields.

    So, your proposed dichotomy “either shut it all down, or do the hard work of trying to thread the needle in the ways allowed by what we already know and keep working” is in a way false. A third alternative is to take a more careful look at “what we already know” and keep working on solving empirically constrained problems and not just aesthetic prejudice.

    Just to be clear, here’s what I mean about (a)-(d) being wrong. (a) & (b) Formal perturbative calculations and lattice methods (where available) do the job just fine and consistently. If you think not, say what cannot be computed using the GR + SM Lagrangian, dimensional regularization, and the renormalization condition that sets to zero all Lagrangian parameters that are empirically unconstrained away from zero. Any non-perturbative statement about consistency is only at the level of conjecture at the moment. (c) Almost precisely the topic of this blog post. (d) Hawking’s calculation is its own explanation.

  21. Peter Shor says:

    Matt: you say “If you think you have better ideas, then please join the fray!”
    Alain Connes has tried to do precisely that with his non-commutative geometry. He has been completely ignored by the physics community. It may be that his ideas don’t work (this wouldn’t be the first time a Fields-medal-winning mathematician has been wrong about things), but I have not found anyone who is able to explain why they don’t work. I would love to hear a good explanation for why these ideas have been ignored.
    A similar thing has happened with the idea (I believe due to Kitaev or Preskill) that physics at its lowest level might not be unitary, but that some kind of quantum error correction makes it unitary for interactions above the Planck scale. Nobody seems willing to consider this. Several of the high energy physicists I’ve mentioned this to dismiss it by bringing up a paper “proving” that if the universe were not unitary, it would have detectable consequences.When this paper was written, quantum error correction was a completely unknown phenomenon, and the paper does not hold up in the light of the existence of quantum error correction.

  22. Peter Woit says:

    Matt,

    No time now for a long response to your comment. I’m heading downtown to the start of a week of talks at CUNY in honor of Jim Simons. The morning ones for the next few days are all ones about QFT at the boundary of math and physics, and I’m very much looking forward to them. There’s a lot of interesting things going on there, unfortunately for physicists this is going on more and more in math departments, not physics departments.

    You should think more seriously about what “imho” has to say. I think the “I’m on your team” is honest. What do you expect other physicists to think when they see publicity campaigns from the most influential people in HEP theory for multiverse nonsense? People like “imho” are the ones deciding whether or not to hire HEP theorists, and even the most sympathetic ones are getting the idea that HEP theory is a disaster area when they see what is being promoted as the cutting edge of the subject. People who have been working on TeV-scale SUSY for decades are now facing a big challenge of how to deal with failure. If they deal with it by arguing that this shows we’re in a multiverse where nothing can be done, they’re slitting their own throats as well as taking down the rest of the field with them. I’m not seeing anyone influential other than David Gross willing to stand up to this publicly. Yes, I undoubtedly spend more time arguing about this than is sane, and all it has gotten me is having links from the arXiv to my blog banned for saying unpleasant things about what powerful people are doing. There are a lot of people out there who should be pushing back against Arkani-Hamed et al’s multiverse campaign. They’re not earning their paychecks.

    Personally, I’m spending this summer trying to finish writing up the material I was teaching this past year, including a lot about basic ideas of QFT from the point of view of representation theory. Hopefully by the end of the summer there will be good draft of a 300 page or so book. I’ve learned a lot, hope to then get back to a list of ideas I find promising, make more progress on them, given what I’ve learned over the last year.

    “But, as you well know, the Standard Model, like all realistic quantum field theories that actually describe practical physics, also predicts that it has a limited regime of validity. So its success and agreement with experiment in that regime of validity does not tell us that it should be valid outside that regime.”

    A long topic, but I really don’t agree with this at all. Asymptotically free gauge theories don’t have limited ranges of validity, and I don’t understand the point of ignoring this remarkable fact. The LHC Higgs results seem to show a Higgs sector that makes sense to very high energies. There’s serious evidence to make one wonder about the whole philosophy that “the SM is just an effective theory, a more fundamental one is some much more complicated mess”.

  23. Matt says:

    I suppose I had assumed that given the stridency and longevity of your opposition, there would be more rigorous substance to your position. There is a mismatch between the certainty with which you seem to be manning the barricades and the magnitude of your evidence.

    Suffice it to say that whatever is the case for, say, QCD alone, the Standard Model as a whole is not asymptotically free. No one is “ignoring this remarkable fact” — it’s just not relevant to the Standard Model. Maybe it’ll be true of some as-yet-unconfirmed BSM model. And where people have actually found UV-complete QFTs equivalent to quantum gravity, like AdS/CFT, you’ve balked.

    You write “The LHC Higgs results seem to show a Higgs sector that makes sense to very high energies.” How do we know this? What does “very high” mean? Does it mean “arbitrarily high” or not?

    You say “There’s serious evidence to make one wonder about the whole philosophy that “the SM is just an effective theory, a more fundamental one is some much more complicated mess”.” What evidence?

    And going from QED to the Standard Model meant adding lots of new parameters, so there’s literally no reason to assume that going beyond the Standard Model is going to mean reducing the number of parameters, either. Don’t get me wrong — it would be nice! But why should Nature care? The progress of physics thus far doesn’t seem to have involved a reduction in parameters, so why should we expect it to?

    It is irresponsible for members of the high-energy theory community to be saying outlandish things in public. But that’s a different crime, and shouldn’t be conflated with the fact of the matter about whether they’re working on the “right” things nowadays in their actual research. Like I said, any new idea that jumps through all the hoops would be a major breakthrough, especially for young theorists who’d rather work on something new than models invented decades ago (but that are the only things still standing).

    And you still haven’t provided a positive agenda here. A positive agenda, not just criticism! Maybe after your textbook is done.

    As for everyone else, it doesn’t count to say “My pet theory is being ignored by the physics community!” If an idea isn’t well-developed, violates trusted principles, is extremely mathematically inaccessible, and/or doesn’t seem to jump through all the necessary hoops, then the onus is on the creator to do the legwork of making his or her case to the larger community. Expecting the physics community to do the work for you is naive, to say the least. The vast, vast majority of new ideas are incapable of getting beyond the blueprint stage.

  24. King Ray says:

    Peter,

    Your comment

    “People who have been working on TeV-scale SUSY for decades are now facing a big challenge of how to deal with failure. If they deal with it by arguing that this shows we’re in a multiverse where nothing can be done, they’re slitting their own throats as well as taking down the rest of the field with them.”

    reminds me of this quote by Seneca:

    “It is sweet to draw the world down with you when you are perishing.”
    Lucius Annaeus Seneca, Roman stoic philosopher, 4 BC –AD 65

  25. fuzzy says:

    dear matt,

    two remarks:

    1) it seems to me a bit preposterous to speak of “crime”. could you tell me since when expressing views (possibly critical views) has became a crime?

    2) you offer very general remarks to “everyone else”. thanks for the consideration, but i urge you to note the fact that, above, i spoke of gauge theories: do you consider it fair labeling the whole class of gauge theories as “my pet theory”?

    note that this is exactly what altarelli is trying to revamp, as in the web site pointed out by marcel v.v.. in other words, it looks to me an item worthwhile including in your “positive agenda”.

    (but maybe you want to discuss only with your Peers, not with some fuzzy guy; in this case i understand your position)

    best regards.

  26. ohwilleke says:

    * It is hard not to sympathize with Einstein. How many physicists really think in their heart of hearts that the couple dozen parameters of the Standard Model and its SU(3)*SU(2)*U(1) structure are just arbitrary? I have yet to meet anyone who has thought seriously about the matter who isn’t convinced that there is a deeper theory that explains what we know through the SM and GR more elegantly and patches up the remaining holes in fundamental physics. What are we missing that makes a formulation of theoretically consistent GR and SM theories impossible? We have an elephant in the room called dark matter that is tired of living in the Harry Potter room under the stairs that cries out for an explanation. We are so close, and yet so far.
    * The “unnaturalness” of the Standard Model is surely a product of the ignorance of the beholder since, of course, it is Nature, however much of a bitch she may be, and decades of meta-theory efforts to define naturalness operationally have clearly missed the point because they are in some way looking at the numbers from a perspective that obscures the missing links that make them natural.
    * The new paradigm really ought to be not BSM but “within the Standard Model” theories that seek to think about “why” the parameters take the values that they do and the equations take the form that they do in a more elegant way.
    * Efforts to link the “texture” of the mass matrix with the values of the CKM and PMNS matrixes, and phenomenological formulas like Koide’s formula and its extensions most directly embrace this WSM approach. But, until we can get a lot more precision in our values for the quark masses is will be hard to distinguish candidate theories; the percentage uncertainties in the lighter quark masses are huge and the theories used to estimate them are still pretty crude so it is too easy to find theories that fit the data. Perhaps improved determination of the Higgs boson Yukawas can move this ball forward by indirectly measuring non-top quark masses via coupling constants that can be discerned with rare decay product production rates.
    * While dark energy can be explained as a simple cosmological constant parameter in GR for gravity, we’ve got to explain dark matter somehow and increasingly it looks like that explanation will be almost completely independent of the Standard Model with the possible exception of a dark matter particle interactions with the Higgs field. (Some recent work on graviweak unification like arxiv 1212.5246 “Gravitational origin of the weak interaction’s chirality” Stephon Alexander, Antonino Marciano, Lee Smolin (20 Dec 2012), for example looks promising but simply coming up for air and looking for alternatives completely outside the SUSY paradigm seems like a good place to start.)
    * Perhaps what the theoretical physics world needs at this point is one huge “Not SUSY” conference to remind people that there are other approaches out there and to give discourages former career SUSY theorists new research directions to explore.

  27. Tue Sorensen says:

    Peter, just want to say I enjoy your blog a lot, and agree with virtually everything you say. Keep it up!

  28. Brathmore says:

    In response to Matt: “If an idea isn’t well-developed, violates trusted principles, is extremely mathematically inaccessible, and/or doesn’t seem to jump through all the necessary hoops, then the onus is on the creator to do the legwork of making his or her case to the larger community. Expecting the physics community to do the work for you is naive, to say the least. The vast, vast majority of new ideas are incapable of getting beyond the blueprint stage.”

    While I agree with this statement, Matt, I think you are attacking a straw man and missing a larger point made on this blog over, and over, and over again: sociological constraints/pathologies prevent physicists (especially young, non-tenured ones) from working on otherwise great ideas that are off the beaten track. If I’ve understood some of Peter’s arguments correctly, a big problem is that leaders in the field have created a situation where working on alternatives to string theory/multiverse mania is detrimental to one’s career.

    The picture you paint of theorists objectively evaluating different approaches solely on their merit is arguably not happening. Instead, the argument is that young theorists pursue string/multiverse ideas due to career pressures and sociological constraints. The refrain you hear from the “leaders” in the field over and over again that strings/multiverse are “the only game in town” exemplifies this. The leaders in the field have devoted their careers to a failed research program, and are unwilling to admit defeat. They’re not disinterested observers seeking the “best theory” – they’re highly biased towards string theory and have channeled the community toward advancing it, at the expense of other good ideas. Through their positions of influence, they have biased funding, hiring, and promotion critera towards string theory far beyond considerations of merit.

    Do you really think that Connes’ ideas are being ignored because this fields medalist overlooked something that every 3rd year graduate student recognizes? That the entire community has evaluated his ideas and decided they can’t lead anywhere? See Peter Shor’s comment about the fact that no one can give him a good explanation for why Connes’ ideas aren’t being pursued. How come **nobody** at the IAS, Harvard, etc. is working on alternatives to string theory? Why aren’t new PhDs at American universities writing dissertations about Connes’ ideas?

    As a frequent reader of this blog, I cannot agree with your argument that this blog is against all BSM physics. His posts on LQG, Lisi’s recent ideas, and Weinstein’s latest lecture don’t seem outright hostile to me. Quite the contrary – I believe he’s argued for a long time that diversity in these ideas should be encouraged.

    No, the argument made frequently on this blog is that the theoretical string community has a sickness. It rejects attempts to pursue competing approaches, not based on objective considerations, but on dogma. Further, practioners in the field frequently tout string theory’s successes in ways that are misleading or outright false. When string theory doesn’t pan out, they argue that the rules of science should be changed, that the accelerator energies aren’t quite high enough…or that their ideas DID pan out! Three cheers for all the recent experimental verifications of string theory.

    So yes – a person proposing a novel BSM surely has a great responsibility in ensuring that their idea passes various tests, but the community also has a responsibility to evaluate them – not to ignore promising ideas due to dogma or sociological constraints. It is here that the community is failing, and attacking the messenger (Peter) in no way changes that fact.

  29. Peter Woit says:

    Matt,

    Maybe best to stick to the main issue here: what progress in HEP has the “SM is just an low energy effective theory for something much more complicated” conjecture led to? Why don’t we see anything at all in terms of effects of operators you would expect to see if the SM is just an effective theory? You say the conjecture tells us where the SM breaks down. Where is that? Does this say we will see something non-SM at the LHC? If we see nothing non-SM at the LHC, what does that mean? Do you accept the argument being made that this means the SM is “unnatural” so it is hopeless to explain its features we don’t understand? What would falsify the “SM is just an effective theory” conjecture?

  30. Jesper says:

    I agree with those who bring up Connes’ work here.

    I don’t think that its a valid objection that the mathematics Connes is applying/developing is difficult (I think that “extremely mathematically inaccessible” is an exaggeration): isn’t it rather conceivable that what theoretical physics needs now is a complete change in perspective and that such a change might very well involve new mathematics? And by way, people like Thomas Schucker have done much work to make the noncommutative framework of Connes’ more accessible to physicists.

  31. A.J. says:

    Regarding Connes & Chamseddine’s ideas:

    The biggest obstacle to attracting more people to work on this stuff is that C&C predicted a Higgs at ~180 GeV. At the time, it was claimed that this was a make-or-break prediction. (Maybe things have changed there; I don’t know.)

    A secondary problem is that it’s difficult for an outsider to tell whether the spectral action principle is actually a deep physical principle or just a clever notation in which nearly any QFT can be expressed. It’s an appealing idea and C&C have claimed that the non-commutative geometries which can reduce to the Standard Model are highly constrained. But it takes more expertise than I have to tell what assumptions they are really making. No-go theorems in QFT tend to have loopholes you can drive a bus through.

  32. Matt says:

    Peter,

    “What would falsify the “SM is just an effective theory” conjecture?”

    I suppose one attitude is just to declare that the Standard Model isn’t effective, that it’s UV complete, which is essentially the same thing as calling off work on new high-energy physics. Unfortunately, the couplings of the Standard Model run, and there’s a Landau pole. On a related point, eventually scattering processes computed using the Standard Model violate unitarity.

    As for Brathmore, all I can say is, yes, lots of people who should know better make mistakes that a very good 3rd-year grad student in theoretical physics wouldn’t make, including plenty of mathematicians. LQG doesn’t work, even at the minimal level of being consistent with everything we know about quantum mechanics and relativity, and Lisi’s ideas were obviously inconsistent at the very beginning with lots of what we already know. (See, among other people, Distler’s blog on that. But more simply, Lisi just disregards various no-go theorems like Coleman-Mandula without even aknowledging their existence. That’s a totally unserious proposal — if you’re going to violate a no-go theorem, you have to explain which assumptions you’ve evaded.)

    You claim that top people are pushing faddish ideas on young grad students for sociological rather than practical reasons (the practical reasons being that there aren’t any other ideas that don’t clearly violate the bounds we know with great certainty).

    That’s a strong and strident claim, and maligns a lot of people who are working very hard these days. Prove it. Show me some actual, valid, believable directions that are being squashed. Not “pet theories” that the community is ignoring, mind you, or ideas that simply don’t work, or are so abstruse and convoluted that their creator has a reasonable duty to make the case with specific details. Actual solid ideas that thread the million-dimensional needle, that have relativistic spacetime and quantum mechanics and can accommodate the chirality and gauge groups of the Standard Model, but extend the Standard Model to higher energy scales. (If at all possible, be sure they somehow also include dark matter and gravity in them. But that’s only for bonus points.)

    It’s easy to declare that it’s all sociology, but I claim it’s just the nature of the subject itself. A young theorist with a bold idea that actually works and threads the needle would be the hottest thing on the scene, and everyone knows it.

    It’s also easy just to demand that people working on all this stuff throw everything away they’ve been working on and stare at a blank sheet of paper, or a sheet of paper with, I don’t know, the Standard Model Lagrangian on it. Maybe shout epithets at it and demand a new idea that looks beautiful or something. I don’t have to tell you that doesn’t work. Coming up with that idea consistent with all the constraints is really, really hard, especially if the demand is to do it from scratch rather than start from BSM models that already thread the needle, which is ultimately the primary reason (not sociology) for why most people take that route.

    That’s one of those things that people outside high-energy theory tend to underappreciate, just how stringent and manifold the constraints are.

    And in the few instances where people have actually been lucky enough to find models that actually work completely and consistently with all the constraints, they’ve essentially all turned out to be dual to stuff we already had. Not just the five string theories to each other, or 11d supergravity, but even things like string theory to certain QFTs or various QFTs in various dimensions with each other. That only makes things even harder, because the idea has to be not only consistent with all the constraints, but also not secretly dual to models already being worked on.

    I think I’ve made my point, and made my challenge to you all clear — namely, for an actual, concrete, positive agenda, rather than just free-floating negativity from the peanut gallery. What you decide to do with it is entirely up to you. At this point, I think I’ll take my answer off the air.

  33. Peter Woit says:

    Matt,

    While you’ve done an excellent job of responding in detail to Brathmore, you answered none of my questions at all.

  34. Jesper says:

    The failed Higgs prediction of Connes’ was perhaps sold too hard – if you read his recent papers the Higgs mass is not a problem for his approach.

    To me, the interesting point about Connes’ work is that the entire SM couple to GR is formulated as a single gravitational theory – with the entire gauge sector arising through inner automorphisms (including the Higgs sector). So probably Einstein would have been thrilled by this. There are challenges, of course, but I think its a very interesting change of perspective that deserves attention. The fact that the SM fits into this framework is not trivial.

  35. Matt says:

    I did answer a couple of your questions already about why we think the Standard Model is only an effective theory, although the deeper reasons are just that the old ways of thinking about the origin of QFTs (magically “quantizing” a given classical field theory and then sticking in some sort of cutoff by hand to hide infinities or something) don’t make any physical sense from a fundamental point of view, whereas recognizing that QFTs inevitably describe the low-lying spectrum of states of a relativistic quantum theory with local interactions actually does make physical sense and explains why it all worked to begin with.

    I mean, if you discovered that the sound you hear at night isn’t actually space aliens but is just crickets, why would you continue to believe it’s space aliens, just because that idea seems more elegant to you?

    And surely you recognize that effective field theory is a powerful technique. Among countless examples, it works for low-energy nuclear physics very well (see the pion Lagrangian), you can use it to compute low-energy quantum corrections to gravity, it works great for making model-independent predictions in cosmic inflation, and you can even use it for fun stuff like estimating the Rayleigh scattering effect in our atmosphere.

    But, most importantly, if your given model doesn’t work at arbitrarily high energies (running couplings, Landau poles, unitarity violations, what have you), then it must be an effective theory. QED is the most obvious example. So was the Fermi theory, and also the theory of massive intermediate vector bosons.

    But let me answer some more of your questions: “Why don’t we see anything at all in terms of effects of operators you would expect to see if the SM is just an effective theory? You say the conjecture tells us where the SM breaks down. Where is that?”

    Surely you know the list, which is long, but probably the most obvious pieces of experimental evidence for the insufficiency of the operators already in the Standard Model are neutrino masses and the wrong amount of CP violation.

    Now please answer my own questions, concretely and specifically. Again, I’d prefer to take my answers off the air. Thank you for your time.

  36. Brathmore says:

    In response to Matt: “Actual solid ideas that thread the million-dimensional needle, that have relativistic spacetime and quantum mechanics and can accommodate the chirality and gauge groups of the Standard Model, but extend the Standard Model to higher energy scales.”

    Matt,

    You have a lot of points that seem valid to me. However, there certainly are areas where I disagree with you. Beyond the posts we’ve already exchanged, I would add that you seem to be applying a **much higher and more unrealistic** bar to non-string theory proposals than to string theory itself. It’s my understanding that thousands (perhaps ten of thousands) of papers have been written in string theory by perhaps as many researchers – and the theory is still far from complete or finished!

    That doesn’t bother me, mind you – but now you seem to be saying that to even get a hearing, a person essentially has to provide a final theory that already threads this “million-dimensional needle.” Is this standard the same that has been applied to string theory? (Perhaps the needle should have included a few extra dimensions, e.g., 10^500?).

    It seems to me that string theory grew as a field as more and more intelligent people thought about the issues in it. To expect a single person such as Lisi or Connes to invent a fully developed, alternative BEFORE receiving input from the lager community is simply preposterous. That there are flaws in their work should be expected, as they haven’t had the benefit of having dozens or hundreds of other people helping to refine their ideas. The physics community should exhibit some more openness about pursuing non-stringy ideas.

  37. Anonyrat says:

    IMO, Brathmore is right, super string theory would not have gotten off the ground with the standards Matt seems to be imposing on new ideas for them to be worthy of consideration.

  38. Peter Woit says:

    Matt,
    It’s been a busy day here and you’ve written some long comments, hard for me to know where to start in terms of responding to them. Happy to try and discuss specific questions, it would be helpful if you could point me to ones that you
    feel are important and not getting answered. I’m not understanding your reference to “off the air”.

    To respond to your latest comment: obviously the SM has problems, I just don’t see evidence that this means it needs to be conceptualized as just an effective theory. It seems equally plausible that it’s a truly fundamental theory, with some aspects that we don’t understand. More precisely, the deep nature of the mathematics of quantized gauge and spinor fields, together with asymptotic freedom in the non-abelian case to me means that a large part of the theory is both fantastic mathematics + rigorously well-defined at all distance scales, with virtually no free parameters. It doesn’t get better than that, in particular I can’t see a sensible proposal for something “more fundamental” that does better.

    Yes, the U(1) gauge field behavior is a problem. The Higgs sector is a big problem: it’s both a non-geometric part of the theory, not well-defined at very short distances, and responsible for most of the free parameters. Sure, quite possibly the Higgs field is an effective field describing something much more interesting we don’t yet understand. I still haven’t given up hope that detailed studies of the Higgs sector in my lifetime will provide some solid evidence of non-SM behavior there.

    About the more general issue here though which most concerns me: I’m not
    arguing that there’s no point to BSM studies. To be used effectively,
    the LHC experiments need guidance about what signals to look for that
    don’t violate everything we already know. But I still think it’s a fact
    that there just aren’t BSM models that make one say: “yes, that’s a
    convincing explanation about something mysterious about the SM”. Put
    differently, I don’t think there are any models out there that it would
    make sense to put any money on unless people give you outrageously long
    odds. About SUSY, it just seems to me to be a very unconvincing class
    of models that has gotten way, way, way too much attention. Yes,
    experiments should look for SUSY, along with anything else people can
    think of, but it should also be acknowledged that this is an unpromising
    long shot.

    About the “Naturalness or Multiverse” campaign, surely I’ve said enough….

  39. Matt says:

    I simply cannot help myself here. In trying to disprove my point, you’ve actually picked an example that exemplifies it. I am imposing the same standards on string theory as anything else. I am not imposing “much higher and more unrealistic” bar to non-string proposals.

    First of all, it took a long time for string theory to get off the ground. Please read the history books. A small number of people worked on it very hard for a number of years (Schwarz, etc.) despite a lot of skepticism (Feynman hated it, and Murray Gell-Mann kept it alive for a while through his influence). This small group showed that it was consistent with quantum mechanics, relativity, and could accommodate all the known features of the Standard Model — not to mention finally including gravity and unification more generally. And, even then, the larger community basically didn’t care until the first superstring revolution in 1984 showed that string theory, beyond all that, also seemed to promise some uniqueness because of anomaly cancellation.

    String theory is the very ideal model of how to get a new idea off the ground — work on it, make sure it gets through the hoops, and then the community will be willing to look at it seriously. There are no double-standards here.

    The trouble with string theory has never been that it doesn’t thread the needle, but that it doesn’t uniquely predict the Standard Model. The early hopes (including from all the dualities) that it would give unique predictions didn’t work out.

    The main trouble is that it doesn’t appear to have a unique low-energy solution. (Of course, any theory at the Planck scale is going to suffer from the problem that when you cool things down to present-day energies, there may be a nontrivial spectrum of inequivalent low-energy solutions. The Standard Model is no exception, although the low-energy solutions are molecules and humans, because the overall energy scales are much lower than the Planck scale and don’t involve gravity.)

    That’s the problem with string theory. But string theory has nonetheless served as a huge testing ground for ideas for the simple reason that spin-off ideas generated by string theory are more likely than models plucked from thin air to be consistent with all the necessary constraints. That’s why so many BSM ideas originated as spin-offs from string theory, although many do not depend on string theory being the correct theory of Nature.

    The same standards apply to all the other ideas, too — uniqueness isn’t even one of the conditions, any more than it is for string theory. (Although, like I said, the possible appearance of uniqueness was a big deal in the early days of string theory.)

    If you have a better idea, then work on it and show that it goes through all the hoops. There are a zillions potential bad ideas that just don’t work, so the onus is on you — don’t expect everyone else to drop their work and do your homework for you, and then, when they don’t comply, start complaining that your pet theory is being “ignored by the establishment.”

  40. Matt says:

    That last comment wasn’t to Peter, but to the other two posters before his.

    Peter,

    I appreciate your taking the time to comment.

    You write “I just don’t see evidence that this means it needs to be conceptualized as just an effective theory.” Being an approximation that doesn’t accommodate observed experimental evidence is what it means to say a theory is only an effective theory. Obviously it needs some sort of modification. But there are no renormalizable operators that are allowed by the theory that we can add to accommodate these unexplained experimentally-observed phenomena, so we can either add higher-dimension operators or devise some new high-energy theory for which the Standard Model is only an effective low-energy theory — and both approaches are equivalent, as you surely know.

    Then you write “It seems equally plausible that it’s a truly fundamental theory, with some aspects that we don’t understand. More precisely, the deep nature of the mathematics of quantized gauge and spinor fields, together with asymptotic freedom in the non-abelian case to me means that a large part of the theory is both fantastic mathematics + rigorously well-defined at all distance scales, with virtually no free parameters. It doesn’t get better than that, in particular I can’t see a sensible proposal for something “more fundamental” that does better.”

    I’m rather surprised to hear you say that being “fantastic mathematics” is a valid criterion for good physics. And saying that “part” of a theory is rigorously-defined at all distance scales (presumably the parts like QCD that are asymptotically free) doesn’t help, because there are also parts of the theory that are not rigorously-defined at all distance scales. And, besides, QCD is rigorously defined at all distance scales for what we now understand are some fairly prosaic reasons — vacuum magnetization wins over vacuum polarization due to the number of colors versus the number of flavors. It’s a delicate cancellation between magnetic and electric effects that depends sensitively on the number of gluons. If the number of flavors were slightly higher compared to the number of colors, then all of a sudden the theory isn’t rigorously defined at all distance scales.

    You write that the Higgs mechanism is bad in part because it is a “non-geometric part of the theory.” Again, I’m not sure why we should demand that Nature must be geometric, or require it as part of a valid scientific theory. Principles like quantum mechanics and relativity are known empirically, and to astonishing precision, and they place very strong constraints on valid scientific theories. Imposing geometry is just human prejudice, no better than saying string theory is right because it’s mathematics is also beautiful.

    There are deeper reasons why geometric (and non-geometric) mathematical structures had to appear in Nature at the levels where they did, reasons that no longer involve simply demanding that Nature be geometric. And, as a proof of concept, we now have lots of extensions like AdS/CFT in which geometry is an emergent property that has no meaning at a fundamental level and can dissolve in certain phases of the theory.

    It’s nice that many models in physics have a geometric description — that makes it easier to use our intuition and various mathematical techniques, but it’s asking a lot to demand that Nature respect our love for geometry as some sort of additional fundamental principle. There’s no numerical, high-precision “geometric constraint” provided by experiment.

    Next, you say “But I still think it’s a fact that there just aren’t BSM models that make one say: “yes, that’s a convincing explanation about something mysterious about the SM”. Put differently, I don’t think there are any models out there that it would make sense to put any money on unless people give you outrageously long odds.”

    I agree. So would most people actually working on this stuff rather than making showy public pronouncements, which I agree with you are not helpful. But these are the models we have now, and people are studying them to learn and are also looking hard for more. My larger point is very simple — models that work are very, very hard to find, and simply yelling at physicists for not finding models that you like is not helpful.

    I’ve noticed that you have only two papers on the arXiv — one on representation theory for QFT, and one on why string theory isn’t any good. You would be serving physics far better to start looking for models yourself and putting your own positive ideas and a positive agenda out there than complaining that the rest of physicists aren’t doing things the way you want them to or working fast enough for you to find new models that actually thread the needle. Write some papers, give talks, make some contributions. See for yourself how hard it is to make progress given all these constraints. Certainly that would win you some credibility.

  41. Peter Woit says:

    Matt,

    Absent better experimental guidance, personally I think mathematics is one of the few available places to look for inspiration. Others may prefer naturalness and effective field theory ideas. Best if different people try different things. My only point is that if pursuing your favorite ideas leads you to a dead end like the multiverse, you should admit it’s a dead end and try something else, not go on a campaign to convince everyone else that your dead end is the only possibility.

    I’m well aware how difficult progress is at this point, the things that look most promising to me are far from easy. Maybe some day I’ll get somewhere with them, maybe not. But if I don’t I won’t try and convince others to give up because I reached a dead end.

  42. Matt says:

    Peter,

    That’s a very gracious and reasonable reply. “Best if different people try different things” — I couldn’t agree with you more. “But if I don’t I won’t try and convince others to give up because I reached a dead end.” Thank you for that.

    For what it’s worth, I don’t think everyone is saying the multiverse is the only possibility — although some are. But I know a lot who accept it only unwillingly — only through gritted teeth — and would happily jump at the chance for another idea that works. That’s not how fads work.

    But the multiverse is unfortunately a possibility. Ideally we’ll find better ones, but we can’t just snap our fingers and make a more palatable idea appear. Nature may well work this way, regardless of human preferences. If that’s the case, then at best we can extract some kind of statistical predictions or something. But maybe not. That would be a tremendous tragedy, but Nature doesn’t care. We can’t just stamp our feet and make demands. Nature doesn’t give us guarantees.

    Einstein once said, back in 1921, “Raffiniert ist der Herrgott, aber boshaft ist er nicht” — “Subtle is the Lord, but malicious He is not.” When he was asked about this remark later in his career, though, he apparently replied “I have second thoughts. Maybe God is malicious.”

    Ultimately, I think we’re all hoping for the same thing. Experimental data is coming in agonizingly slowly, especially anything that’s outside the regime of validity of the Standard Model, and people are really doing the best that they can with what’s available. As you note, it’s not easy, sources of inspiration are valuable wherever we can find them, and people are putting their lives into their work.

    I just wish sometimes that we could all tone down the negativity toward each other. It’s hard enough struggling to come up with workable ideas, especially for young physicists, without having prominent people (on various sides) bashing people’s hard work and impugning their motives in front of a public that doesn’t know the difference between one area of physics and another, or even between experiment and theory for that matter, and who frankly think that most physicists are just coming up with crazy ideas without any constraints at all. To a young physicist, I’m sure the impugning of motives and the calls (even if only indirectly) to cut funding comes across as downright mean.

    I also fear it’s self-defeating to the whole enterprise in the end. Sniping between physicists contributed to the failure to build the SSC, and probably next-generation accelerators in the US that would have come after it, and the result is a lot less experimental data, which hurts everyone in the field. And it also turns off a lot of young people, some of whom might be the ones to find the new ideas we need.

    There’s a place for criticism, but, ultimately, it’s far, far more productive and beneficial in every conceivable way to go out and do the grueling task of finding better ideas that actually work. At the very least, that buys a person a lot of credibility when it’s time for more criticism.

    It’s a big universe, whether it’s a multiverse or not. There’s room for all of us in it.

  43. amused says:

    Matt:

    Most of the issues you raised were already beaten to death during the great string theory punch-up a few years ago – see the ST-related posts on the cosmic variance and asymptotia blogs. But since it seems you are from a younger generation and missed the fun of all that, let me regurgitate a bit of it for you…

    “You claim that top people are pushing faddish ideas on young grad students for sociological rather than practical reasons [...] That’s a strong and strident claim, and maligns a lot of people who are working very hard these days. Prove it. Show me some actual, valid, believable directions that are being squashed.”

    Well, would you consider the problem of non-perturbative formulation of chiral gauge theories on the lattice to be a worthwhile direction? It would be nice to know if the gauged chiral symmetry of the SM really is spontaneously broken (or, equivalently, if the Higgs field really does have a nonzero expectation value), don’t you think? Instead of just assuming that it is and then setting up perturbation theory based on that assumption. But then you will need a nonperturbative formulation of the SM to find out… And it would be nice to know at what temperature (if any) the gauged chiral symmetry is restored too, right? Presumably that would be relevant for models of the evolution of the universe… You will need a nonpertubative formulation for that too.

    So here is a question for you: if a young person was naive and foolish enough work on the above, and sought to document his/her progress through single-author publications in PRL, how many such publications would it take for him to balance, in the competition for jobs, one publication in, say, PRD, by a another young person jointly with his famous advisor and a bunch of other more senior and prominent people in the area of string/multiverse/bsm? Don’t be wishy-washy now, give us a number.

    And since you asked for it, here are a random couple of examples of “being squashed”: this guy and this guy.
    (Neither of them are me or people I know, just random examples I happened to notice, and there are plenty more.) Check out their impactful (highly cited) and independent research track records, then look up their career outcomes and compare with the outcomes for typical members of the string theory group at
    this prominent institution (for example). From that it will be clear what things really matter and don’t matter for career advancement in this business.

    When I was a young person starting out in this business i naively though the situation re career advancement was like this: We all place our bets by what we decide to work on, and then the onus is on each of us to show that our bets are working out. Those who are able to make progress on problems that are considered important (as judged, e.g., by the editors and referees of PRL) will be rewarded, and those who don’t won’t. Turns out I couldn’t have been more wrong about that.

    Since you seem to be a newcomer to these debates let me answer in advance the usual protest from the ST/BSM crowd to the points above: “But our topic is so DEEP and DIFFICULT so we need to be given a dispensation and not held to the same standards of documenting important progress as the rest of the community. No one but us is qualified to evaluate our work, and our wonderful results are far too technical to explain in a PRL article.” Fine, ok then, instead of PRL you may instead use that prominent string theory journal the Op-Ed Section of the NY Times.

    “I’ve noticed that you have only two papers on the arXiv…”

    Disparaging someones publication record behind the veil of anonymity is rather bad form. Is your own research activity and publications impeccable and above any criticism? Any single-author PRLs recently? ;-)

    I suggest you reflect on why you decided to write a comment here in the first place. If it was just Woit and a bunch of crackpots hanging out here you wouldn’t have bothered. But as you know, the readership includes many professional physicists in various areas, including HEP theory, who share to a greater or lesser extent (some of) the views Woit expresses. They are doing positive things in their own work, and yet Woit’s negativity on aspects of ST and BSM work resonates with them. So you thought you might be able to change their minds on those views by attacking Woit’s research contributions? Ha.

    “See for yourself how hard it is to make progress given all these constraints.”

    Probably I’m just a simpleton but it seems that paths to uncovering new physics beyond the SM are becoming easier these days if you choose good ones, e.g. this one.

    Admit it now that when you talk about “BSM” you really mean “BSM topics that are sufficiently grandiose to warrant the attention of myself and my illustrious peers. Any other, e.g. bottom-up type, approaches to BSM physics might as well not exist.”

  44. Jesper says:

    “It’s a big universe, whether it’s a multiverse or not. There’s room for all of us in it”

    well – thats the point. Its not, and there isn’t. Sadly.

    Try as a young researcher to work on your own ideas and apply for funding. Then you’ll reach the boundary.

  45. Marcel van Velzen says:

    @Mario. Correct, Altarelli many discusses naturalness in the light of supersymmetry.

  46. Anonyrat says:

    http://www.math.columbia.edu/~woit/wordpress/?p=2288

    quotes Gell-Mann:

    I was a sort of patron of string theory — as a conservationist I set up a nature reserve for endangered superstring theorists at Caltech, and from 1972 to 1984 a lot of the work in string theory was done there.

    Who are the conservationists/incubators for ideas today, equivalents of Gell-Mann, using their ability to draw funding to support long-shot ideas?

  47. Peter Shor says:

    A.J. says “A secondary problem is that it’s difficult for an outsider to tell whether the spectral action principle is actually a deep physical principle or just a clever notation in which nearly any QFT can be expressed. ”

    As I understand it (which isn’t very well), Connes and Chamseddine’s spectral action construction doesn’t work unless you have Majorana neutrinos, a new sterile neutrino, and a new field that couples to the sterile neutrino. These aren’t radical changes to the Standard Model, and they’ll be hard to see experimentally, but this does seem to demonstrate that not all QFTs can be expressed in non-commutative geometry.

  48. Matt says:

    amused,

    I can only comment on things as I live them now, and today there’s a vibrant community of people in high-energy theory working on all manner of subjects, including non-BSM stuff like collider physics, jets, HQET, and applications of HET to condensed matter, among other things.

    As for determining “if the gauged chiral symmetry of the SM really is spontaneously broken (or, equivalently, if the Higgs field really does have a nonzero expectation value), don’t you think?”, or whatever you wanted to work on, all I can say is that demonstrating that roadblocks you suffered were a consequence of sociology rather than the viability and potential of the work itself is still undetermined.

    Your list of names brings to mind two favorite SMBC comics, both on the use of anecdotes:
    http://www.smbc-comics.com/?id=2159
    http://www.smbc-comics.com/?id=2307

    For someone who claims not to be impugning people’s motives but just telling things like they are, you do an awful lot of impugning of people’s motives, like mine in particular.

    For example, my point in citing Peter’s list of papers on the arXiv was to urge him to go out and work on this stuff rather than simply criticizing it from afar. It matters to his case that he doesn’t show outward signs of working on this stuff himself. It’s not a matter of disparaging him. You were sneaky to truncate my quotation where you did — I encourage people to go read the rest of that paragraph.

    But then you turn around and attack my record, for no obvious reason except to disparage me, as though that accomplishes anything other than a fallacious appeal to emotion. None of this is remotely relevant to the argument I’ve been making here.

    You write “But as you know, the readership includes many professional physicists in various areas, including HEP theory, who share to a greater or lesser extent (some of) the views Woit expresses.” I have no idea who reads Peter’s blog. I don’t stop by all that often — I just saw a post that I wanted to respond to, because I thought Peter was saying things about his own understanding of the Standard Model and what I viewed as a larger shift toward general antipathy toward all things BSM.

    “So you thought you might be able to change their minds on those views by attacking Woit’s research contributions? Ha.” No. It’s rather presumptive of you to declare what my motivations are, don’t you think? I think I made my goals and requests very clear, and none of it involved “chang[ing] their minds” or attacking anyone’s research.

    “Admit it now that when you talk about “BSM” you really mean…” I won’t admit anything I don’t believe.

    I don’t know you, so I won’t start ascribing beliefs or opinions to you that you don’t possess. But whatever you’re like in real life, you don’t seem like a very pleasant person on the Interwebs. I’m not an apologist for the ways of academia, which has plenty of problems. I was simply commenting on a narrow issue that I thought Peter was incorrect about.

    I think that’s about it for me. At the usual risk of not having the last word, I really have to get back to work now.

  49. Peter Woit says:

    Matt/amused,

    Enough, please. I’d like people to stick to attacking me here, not each other. For the record, I think Matt is quite right to point out that I should be writing papers, amused is quite right to point out that there is no place in the current HEP job market for those pursuing research programs outside a quite narrow range. Other than that, best for all to attempt to be charitable in considering the motivations of all those making arguments here. I try and delete the really unreasonable ones….

  50. martibal says:

    @Jesper: very nicely said. Of course there is no space for all of us. There is as war for fundings and, as all war, this is pretty dirty and at the end the story is written by the winner. The claim that “scientific excellence is the main criteria of selection” (that would be equivalent to Matt admonition: “stop complaining and show your ideas are the best”) does not survive the analysis: just compare the scientific production of young persons that have been permanently hired because they were supposed to be “the most promising young scientists of the year”, with the scientific production of – say – permanently precarious postdocs. In number of cases (not negligible at all), a couple of years after the hiring and whatever weight you put on the criteria (number of papers, of co-authors, of citations, quality of the reviews) it is hard to get convince that the most- promising-young-scientist always held his promises. I do not think anybody honest would deny that politics is an essential aspect of the hiring process.

    -

    @Peter: in Connes approach to the SM, the Higgs is completely geometric. It comes out as a component of the connection (in the noncommutative part of the geometry), exactly in the same manner as usual gauge fields come out as connection 1-forms (on the commutative part of the geometry). If one considers the formula of the distance in noncommutative geometry (which generalizes Riemann geodesic distance), one can even see the Higgs field as the component of the metric in some discrete internal dimension. More geometric than that… &#128521

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