Lost in Math

Sabine Hossenfelder’s new book Lost in Math should be starting to appear in bookstores around now. It’s very good and you should get a copy. I hope that the book will receive a lot of attention, but suspect that much of this will focus on an oversimplified version of the book’s argument, ignoring some of the more interesting material that she has put together.

Hossenfelder’s main concern is the difficult current state of theoretical fundamental physics, sometimes referred to as a “crisis” or “nightmare scenario”. She is writing at what is likely to be a decisive moment for the subject: the negative LHC results for popular speculative models are now in. What effect will these have on those who have devoted decades to studying such models?

Back in 2006 Lee Smolin and I published books concerned about where fundamental physics was heading, and five years ago Jim Baggott’s Farewell to Reality appeared with another take on these issues. Hossenfelder’s is the first book on this topic to appear since the LHC results showing a vanilla Standard Model Higgs and no evidence of supersymmetry or other speculative BSM physics. The remarkable thing she has done is to address this in a characteristically direct manner: go talk to those responsible and ask them what they have to say for themselves.

Four of the people that Hossenfelder interviews would be on any short list of the most influential figures in theoretical particle physics, both responsible for where we are now by their past actions, and looked to by others for a vision of where the field is going next. They are Nima Arkani-Hamed, Steven Weinberg, Frank Wilczek, and Joe Polchinski.

Arkani-Hamed is introduced with:

He’s won loads of awards, including the inaugural 2012 Breakthrough Prize for “original approaches to outstanding problems in particle physics.” The problems are still outstanding. So is Nima.

and here’s an extract from the interview

“Has the LHC changed your perspective on naturalness?” I ask.

“It’s interesting–there is this popular narrative now that theorists before the LHC were totally sure that susy will show up, but now there’s a big blow. I think that the people who are professional model builders, the people I consider to be the best people in the field, they were worried already after LEP… The good people, they were not at all sure susy would show up at the LHC. And nothing has changed qualitatively since 2000. Some loopholes have been closed, but nothing has changed qualitatively…”

As with many of the interviews, Hossenfelder intersperses her own internal response to what she’s hearing:

But not one of those “best people” spoke up and called bullshit on the widely circulated story that the LHC had a good chance of seeing supersymmetry or dark matter particles.

She doesn’t mention, but surely is aware, that many prominent theorists pre-LHC had made public bets that the LHC would find SUSY, and that those wagering this way included Arkani-Hamed himself. For accounts of the 2016 Copenhagen event where the bet was paid off, see here and here. You can read there what Arkani-Hamed had to say then about losing the bet, and the quote:

“I think Winston Churchill said that in victory you should be magnanimous,” Damgaard said after Arkani-Hamed’s talk. “I know also he said that in defeat you should be defiant. And that’s certainly Nima.”

In the interview with Hossenfelder, Arkani-Hamed goes on to say:

The people who were sure it would be there are now positive it’s not there. There are people now who speak out about being depressed or worried or scared. It drives me nuts. It’s ludicrously narcissistic. Who the fuck cares about you and your little life?

There’s a lot more in the interview and you should get the book and read the whole thing. Hossenfelder does a wonderful job of portraying both Arkani-Hamed’s serious arguments and his aggressive “Damn the torpedoes” self-confident attitude. This is not someone who is going to admit that, whatever bet he lost, some failure has occurred that indicates this is a time for reflection on mistakes made and reevaluation of the path forward.

Hossenfelder travels to Austin, Texas to talk to Steven Weinberg, who it appears may not realize she is a physicist, just has been told he is supposed to talk to a “writer”. She notes that:

Weinberg doesn’t talk with you, they told me, he talks at you. Now I know what they mean. And let me tell you, he talks like a book, almost print-ready.

I won’t try and reproduce much of her conversation with Weinberg, the multiverse is a main topic (she thinks it’s an empty idea, Weinberg is willing to go along with it). About where particle theory is headed, Weinberg says:

I don’t know how much elementary particle physics can improve over what we have now. I just don’t know. I think it’s important to try and continue to do experiments, to continue to build large facilities… But where it will end up I don’t know. I hope it doesn’t just stop where it is now. Because I don’t find this entirely satisfying…

I don’t take seriously any negative conclusion that the fact that the LHC hasn’t seen anything beyond the standard model shows that there isn’t anything that will solve the naturalness problem… Supersymmetry hasn’t been ruled out because it’s too vague about what it predicts.

Her next interviewee is Frank Wilczek, who she finds in Tempe, Arizona. His take on string theory unification is rather negative:

… it’s not clear what the theory is. It’s kind of miasma of ideas that hasn’t yet taken shape, and it’s too early to say whether it’s simple or not–or even if it’s right or not. Right now it definitely doesn’t appear simple.

Asked about the argument that string theory could reproduce gravity, Wilczek responds:

If your standards are low enough, yes. But I don’t think we should compromise on this idea of post-empirical physics. I think that’s appalling, really appalling… If there was any bit of experimental evidence that was decisive and in favor of the theory, you wouldn’t be hearing these arguments. You wouldn’t. Nobody would care. It’s just a fallback. It’s giving up and declaring victory. I don’t like that at all.

Wilczek is still unwilling to give up on SUSY and the idea of a SUSY GUT, with his main argument the coupling constant unification calculation he did with Dimopoulos and Raby back in 1981:

“They haven’t found susy partners, though,” I say. “Is this something that worries you?”

“I am starting to get worried, yes. I never thought it would be easy. There have been bounds from [the LEP experiments] and proton decay for a long time, and this indicated that a lot of the superpartners have to be heavy. But we have another good shot with the [LHC] energy upgrade. Hope springs eternal… I would definitely not believe in supersymmetry if it wasn’t for the unification of gauge couplings, which I find very impressive. I can’t believe that’s a coincidence.”

It’s not mentioned in this book [actually, she does mention this], but Wilczek has already paid off one bet about SUSY (with Garrett Lisi) and likely will have to pay off another next year. I don’t know if by “energy upgrade” he’s thinking of the HE-LHC, or the 100 km much bigger proposed ring, but in any case those won’t happen before at least 2040. No matter what happens, I don’t think Wilczek will ever change his mind about the SUSY-GUT paradigm he has found attractive since the 1980s.

In January 2016 Hossenfelder traveled to Santa Barbara to talk to Joe Polchinski, who was already sick with the brain cancer that ultimately would take his life two years later. Unlike Wilczek, Polchinski was a fan of string theory and of evaluating it by “post-empirical” criteria. He at one point published a “Bayesian” calculation arguing that string theory is correct with probability “over 3 sigma” (i.e. over 99.7%). Asked about prospects for a unified theory, Polchinski says:

I think string theory is incomplete. It needs new ideas… But string theory has been so successful that the people who are going to make progress are the people who will be building on this idea.

Arkani-Hamed, Weinberg, Wilczek and Polchinski reflect a range of points of view about the current situation and what it means. Unfortunately it seems to me that they share an unwillingness to face up to failure, and this doesn’t bode well for the future of particle theory, with “more of the same” the agenda that is being set.

Besides these four interviews, the book also contains accounts of meeting and discussions with quite a few other physicists, all well worth reading, and often written with a sly humor. The description of visiting Garrett Lisi on Maui is not to be missed, and he has a lot of sensible things to say (“For a surf bum, he’s surprisingly intellectual” the author writes). He tells the story of how Jacques Distler and others threatened (unsuccessfully) to organize a boycott of Scientific American if it published an article by him. In addition to the interviews there’s a great deal of valuable discussion of the problems with the way research is organized and the reward structures scientists operate under (for instance, publicly admitting failure is definitely on the “not encouraged” list).

So far I’ve ignored the main framing device that Hossenfelder uses throughout the book, that of her questioning the idea of “beauty” as a motivation for evaluating ideas about physics. This is not because I disagree all that much with what she writes, but instead that I fear a complex set of issues is likely to get over-simplified, and this over-simplified version of the book’s argument is all that much of the public is ever going to hear about it. Hossenfelder explains that the concept of “beauty” she is challenging is a specific set of ideas about “symmetry, unification and naturalness” that she sees as dominating physics research. I agree that there’s a problem with this specific set of ideas and how they have been used, but I’d keep them separate and don’t see putting them together as “beauty” to be helpful. At various points she makes it clear that her worry is that we are getting stuck due to outdated notions of “beauty”, while still believing that successful new ideas will come with a new form of “beauty”.

The book ends with

We know that the laws of nature we presently have are incomplete. To complete them, we have to understand the quantum behavior of space and time, overhauling either gravity or quantum physics, or maybe both. An the answer to this will without doubt raise new questions…

…There’s much work to do. The next breakthrough in physics will occur in this century.

It will be beautiful.

Update: Science magazine has a review. For some reason they seem to have decided it was a good idea to have the book reviewed by a postdoc doing exactly the sort of work the book is most critical of. The review starts off by quoting nasty anonymous criticism of Hossenfelder from someone the reviewer knows on Facebook. Ugh.

Update: I’ve written a similar but somewhat different version of this review for MAA Reviews, one aimed more at mathematicians.


Update
: More reviews here and here, as well as a posting from Hossenfelder where she explains her current professional situation in the context of deciding to write the book.

Update: I’m glad to see that Science has edited the review there to remove the use of an unattributed quote.

Posted in Book Reviews | 61 Comments

Back at Work

Now back from a week away, mostly spent in Cambridge. Among the accumulated items of interest:

  • Inference has a review of my book, Woit’s Way, by Andrew Jordan. I like the way it starts out:

    Quantum Theory, Groups and Representations is based on a series of lectures that he gave at Columbia University.

    And it is excellent.

    The review gives a very good explanation of what’s in the book, what level it’s at, and what I’m trying to accomplish. Besides getting all this right, he also gets right some of the things that could have been done better (I did the indexing and I’m kind of lazy, it should have at least twice as many entries).

    A reminder: the book is available either in my version at my website, or from Springer here.

    By the way, when I was in Cambridge I spent a couple days at the conference in honor of Bert Kostant, who was a major figure in the study of the relation of representation theory and quantization. Among the talks there, David Vogan gave a survey talk on Quantization, the orbit method, and unitary representations. He explains clearly the fundamental relationship between representation theory and quantum theory that is central to my book. Roughly the first half of the talk corresponds to topics discussed in the book. I decided to not write about the topic of the second half of Vogan’s lecture, the representation theory of reductive groups and the orbit method, since that would take the book in a different direction, one currently of more interest to mathematicians than physicists (and Vogan has already done a better job of writing about this topic than I ever could).

  • Also in the new issue of Inference are several pieces commissioned as responses to Natalie Paquette’s wonderful survey article A View from the Bridge about topological QFT and influences running from physics to mathematics. These pieces include takes on the relation of math and physics from Édouard Brezin, John Iliopoulos, Hirosi Ooguri and Martin Krieger, as well as a rather odd one from string theorist Xi Yin.

    Yin’s piece is entitled An Ode to Ugly Physics, and he argues that:

    the deepest and most far-reaching ideas of physics are not the most elegant or beautiful, but the ideas that are confusing, not rigorous, improperly formulated, or, in fact, utterly incomprehensible to mathematicians.

    One problem is that many of the examples he gives of “ugly” physical ideas (for instance, spontaneous symmetry breaking) are ones that I think most mathematicians would describe as rather beautiful. He’s right that some of the examples he gives (e.g. complex string theory calculations) are ones that mathematicians wouldn’t find that beautiful, but often these are calculations that have been unsuccessful in their goal of making contact with reality. Yin ends with:

    I believe that part of the job of a theoretical physicist is to make the lives of mathematicians miserable. There are, incidentally, few things I can think of that could make a mathematician more miserable than reading Leonard Susskind’s papers.

    This includes a footnote to this recent paper by Susskind, and he’s right that this is not one mathematicians would think highly of. For good reason though, with Yin’s implication that this is an important idea in theoretical physics something I find rather dubious (but then again, some would say I’m a mathematician…).

    Truly bizarre is Yin’s response to the fact that string theory has failed to make any connection to observable physical reality:

    I couldn’t help but notice a striking parallel with the way mathematics became detached from physics during the nineteenth century and, in particular, the outrage that accompanied Cantor’s transfinite set theory and Hilbert’s non-constructive proofs. Was the kind of mathematics that could never be exhibited with real objects actual mathematics, or was it theology? With the benefit of hindsight, we now know that the mathematics flourished like never before during the twentieth century. One can only hope the same thing happens with string theory in the decades to come.

    So, having no connection to experiment and observation is not a bug, but a feature, exhibiting a radical new advance in how to do physics? This takes the “post-empirical” thing even further than I’ve seen anywhere else.

    Finally, also in the same issue of Inference is the final part of a series of articles by Sheldon Glashow, this one dealing with the Standard Model. Glashow ends the essay with some comments on string theory, quoting someone I have to agree with.

  • On the neutrino front, there’s a new result out from MiniBooNE that has gotten a lot of attention. As usual, good sources for clear explanations and informed evaluations are Tommaso Dorigo and The Mad Hatter.

    For much more of the latest results on neutrinos, Neutrino 2018 is happening this week in Heidelberg, slides of presentation appearing here.

  • The Perimeter Insitute earlier this year hosted a workshop on geometric Langlands and QFT, talks available here. Dan Falk has an article about this subject here. He also has a piece about Why some scientists say physics has gone off the rails, partly based on Sabine Hossenfelder’s new book, which I’ll write about here very soon.
  • Michael Harris at his book’s blog tells the story of how he was commissioned by New Scientist to write something about Peter Scholze’s ideas. His draft ended up not getting used, luckily for us he includes it in the blog posting. New Scientist did however end up publishing a story about this, under the headline The Theorem of Everything (non-paywalled version here).
  • The Simons Foundation has just put out its 2017 annual report. To get some idea of their increasingly large influence on mathematics and physics research, here are some numbers:

    Assets, end 2017: \$3.298 billion
    2017 income: \$646 million
    2017 expenses: \$409 million
    2017 grants: \$273 million

    Mathematics and physical sciences receive 31.77% of the grant money. To get a sense of the scale of this, one could compare the fraction of expenses corresponding to math and physical sciences (31.77% x \$409 million= $130 million) to the FY 2017 NSF budget numbers

    Mathematical sciences: \$234 million
    Physics: \$281 million
    Astronomical sciences: \$252 million

    In the areas of math, physics and astronomy where the Simons Foundation is concentrating its resources, I suspect that the amounts they’re spending are getting up to the NSF level.

Update: For a take on the Copenhagen interpretation that I very much agree with, see Philip Ball’s Myths of Copenhagen.

Posted in Uncategorized | 7 Comments

Heinz-Dieter Zeh 1932-2018

I was sorry to learn today of the death on April 15th of H. Dieter Zeh, one of the major figures responsible for improving our understanding of the physics involved in the measurement problem and related interpretational issues in quantum mechanics. For an excellent account of the story of Zeh’s work and its early reception, see Adam Becker’s recent book What is Real?. For a very good article about Zeh (in German), see here.

Zeh is the physicist most responsible for first identifying and studying the crucial role of decoherence in the measurement problem. As Becker explains, he encountered a quite hostile reaction to his early work from defenders of Copenhagen orthodoxy. He finally managed to get his paper On the Interpretation of Measurement in Quantum Theory published in 1970, and then started to explore what came to be known later by the term “decoherence”. In later years he wrote many articles explaining these ideas, for one that includes some historical context, see here. Zeh maintained a website with links to his writings, at www.decoherence.de or www.zeh-hd.de, which seems to be down at the moment, hopefully only a temporary situation (a recent Wayback Machine capture is here).

I was pleased that every so often Zeh contributed insightful comments here, most recently just three weeks before his death. Here’s a list of the ones I found in a quick search:

During the past few years I also had some email exchanges with Zeh. For details of his latest thinking about issues like the multiverse, he pointed me to this paper, which he every so often updated. A few months ago I was quite sorry to realize (when someone told me that Zeh lived in Heidelberg) that I had missed an opportunity to try to meet him in person when I was there a couple years ago. I’m even sorrier about this now that such a meeting will no longer be possible.

Posted in Obituaries | 1 Comment

There Are No Laws of Physics. There’s Only the Landscape.

At Quanta magazine, IAS director and string theorist Robbert Dijkgraaf has signed up to the multiverse mania bandwagon with an article announcing There are no laws of physics. There’s only the landscape. Dijkgraaf’s version of the string landscape ideology is:

The current point of view can be seen as the polar opposite of Einstein’s dream of a unique cosmos. Modern physicists embrace the vast space of possibilities and try to understand its overarching logic and interconnectedness. From gold diggers they have turned into geographers and geologists, mapping the landscape in detail and studying the forces that have shaped it.

The game changer that led to this switch of perspective has been string theory. At this moment it is the only viable candidate for a theory of nature able to describe all particles and forces, including gravity, while obeying the strict logical rules of quantum mechanics and relativity. The good news is that string theory has no free parameters. It has no dials that can be turned. It doesn’t make sense to ask which string theory describes our universe, because there is only one. The absence of any additional features leads to a radical consequence. All numbers in nature should be determined by physics itself. They are no “constants of nature,” only variables that are fixed by equations (perhaps intractably complicated ones).

While giving the usual 1995 justification for the “M-theory” conjecture of a unique string theory, Dijkgraaf neglects to mention that, 23 years later, no one has a viable proposal for what this unique theory might be. He mentions none of the problems of moduli stabilization, or that the theorists “mapping the landscape in detail” don’t actually know what equations govern this supposed landscape and thus have hit a dead-end, unable to predict anything about anything.

The problem is that what Dijkgraaf is writing about is the situation of Theorists Without a Theory, trying to turn this failure into success by arguing that it is a radical new discovery, the discovery that “There are no laws of physics”. He ends with

A more dramatic conclusion is that all traditional descriptions of fundamental physics have to be thrown out. Particles, fields, forces, symmetries — they are all just artifacts of a simple existence at the outposts in this vast landscape of impenetrable complexity. Thinking of physics in terms of elementary building blocks appears to be wrong, or at least of limited reach. Perhaps there is a radical new framework uniting the fundamental laws of nature that disregards all the familiar concepts. The mathematical intricacies and consistencies of string theory are a strong motivation for this dramatic point of view. But we have to be honest. Very few current ideas about what replaces particles and fields are “crazy enough to be true,” to quote Niels Bohr. Like Alice and Bob, physics is ready to throw out the old recipes and embrace a modern fusion cuisine.

The argument seems to be that we need to throw out our highly successful quantum field theories, replacing them with a “radical new framework” describing “impenetrable complexity”. But what is this “radical new framework”? As best I can tell, what’s now popular at the IAS is the “it from qubit” idea that is the topic of this summer’s PITP program. It seems that Witten has taken up the study of quantum information theory, with a new expository preprint just out. I’ll look forward to seeing what the PITP lecturers present, but so far I haven’t seen the slightest indication that this “radical new framework” can get off the ground as a fundamental unified theory.

Posted in Multiverse Mania | 19 Comments

Feynman at 100

The past month has seen quite a few events and articles celebrating the 100th anniversary of Richard Feynman’s birth (see for example here, here, here and here). Feynman was one of the great figures of twentieth century physics, with a big intellectual influence on me and on many generations of particle theorists. In particular, his development of the path integral formulation of quantum mechanics and the Feynman diagram method for calculating and understanding what quantum field theories are telling us are at the center of how we have learned to think about fundamental physics and apply it to the real world.

When I first started studying physics, in the seventies, Feynman was a major figure to physicists, but not that well-known outside the subject. After the 1985 appearance of the book of anecdotes “Surely You’re Joking, Mr. Feynman!” and his 1986 role in the report on the Challenger disaster (followed by more anecdotes in the 1988 “What Do You Care What Other People Think?”) Feynman became a huge public figure. The Physics section of any book store that carried science books would often have nearly a whole shelf of books by and about him, with the only competition the shelf of books about Einstein (the Hawking shelf didn’t get going until a bit later).

I avidly read the Feynman anecdote books when they came out and was suitably entertained, but I also found them a bit disturbing. Too many of the anecdotes seemed to revolve around Feynman showing how much smarter he was than someone else. I hadn’t thought much about this, but was interested to read historian of science Melinda Baldwin’s piece Feynman the Joker this month at Physics Today. It ends with:

But Feynman’s charm and brilliance were only one side of his personality. His writings, and the accounts of those who knew him, reveal a man whose faith in his own brilliance could veer into self-absorption and the mistreatment of others, particularly those whom Feynman didn’t consider his equals. Even people who admired Feynman’s intellectual gifts could become exasperated with his antics, and some important professional and personal relationships went off the rails when that happened. Feynman’s legacy reminds us that it’s important to have fun with physics—but to make sure those around us are having fun too.

I think this is an overly harsh take on Feynman, but do think that his later career suffered from the sort of self-absorption Baldwin points to. She links to an interview with Gell-Mann, which includes:

One of your best-known interactions was with Richard Feynman at Caltech. What was that like?
We had offices essentially next door to each other for 33 years. I was very, very enthusiastic about Feynman when I arrived at Caltech. He was much taken with me, and I thought he was terrific. I got a huge kick out of working with him. He was funny, amusing, brilliant.

What about the stories that you two had big problems with each other?
Oh, we argued all the time. When we were very friendly, we argued. And then later, when I was less enthusiastic about him, we argued also. At one point he was doing some pretty good work—not terribly deep, but it was very important—on the structure of protons and neutrons. In that work he referred to quarks, antiquarks, and gluons, of which they were made, but he didn’t call them quarks, antiquarks, and gluons. He called them “partons,” which is a half-Latin, half-Greek, stupid word. Partons. He said he didn’t care what they were, so he made up a name for them. But that’s what they were: quarks, antiquarks, and gluons, and he could have said that. And then people realized that they were quarks, and so then you had the “quark-parton” model. We finally constructed a theory—I didn’t do it by myself; it was the result of several of us put together. We constructed the right theory, called Quantum Chromodynamics, which I named. And Feynman didn’t believe it.

He didn’t believe that the theory was correct?
No. He had some other cuckoo scheme based on his partons. Finally after a couple of years he gave up because he was very bright and realized after a while that we were correct. But he resisted it, and I didn’t understand why he had to be that way. Partons…

Looking at Feynman’s career, his great accomplishments were in the years 1947-58, and it’s somewhat surprising that he didn’t make major contributions (besides the partons…) to the development of the Standard Model in the years from 1958-73. One contributing factor may have been his insistence on “What I cannot create I do not understand.” John Preskill recounts in a recent talk:

Feynman often told students to disregard what others had done, to work things out for oneself. Not everyone thought that was good advice. One who disagreed was Sidney Coleman, a Caltech grad student in the late 50s and early 60s. Coleman says: “Had Feynman not been as smart as he was, I think he would have been too original for his own good. There was always an element of showboating in his character. He was like the guy that climbs Mt. Blanc barefoot just to show it could be done. A lot of things he did were to show, you didn’t have to do it that way, you can do it this other way. And the other way, in fact, was not as good as the first way, but it showed he was different. … I’m sure Dick thought of that as a virtue, as noble. I don’t think it’s so. I think it’s kidding yourself. Those other guys are not all a collection of yo-yos. Sometimes it would be better to take the recent machinery they have built and not try to rebuild it, like reinventing the wheel. … Dick could get away with a lot because he was so goddamn smart. He really could climb Mont Blanc barefoot.”

A related aspect of Feynman’s working method was a sizable amount of hostility to any abstract mathematics. In his talk at the Caltech Feynman 100 event, Lenny Susskind makes a great point of this, seeing Feynman’s insistence on physical intuition rather than mathematics as a key to his strength. For some problems though, as Sidney Coleman realized, refusing the mathematician’s toolbox may just make it impossible to do what you need to do.

A peculiar aspect of the Caltech scientific symposium was that the two talks on particle physics (by David Gross and Hirosi Ooguri) spent a great deal of time promoting something that Feynman detested. While Gross described a major legacy of Feynman as “a healthy disrespect for authority” and “a total aversion to BS”, those characteristics led Feynman to have a very negative view of string theory, up until his death. He was known to remark that “string theorists don’t make predictions, they make excuses”, and in a 1987 interview stated:

Now I know that other old men have been very foolish in saying things like this, and, therefore, I would be very foolish to say this is nonsense. I am going to be very foolish, because I do feel strongly that this is nonsense! I can’t help it, even though I know the danger in such a point of view. So perhaps I could entertain future historians by saying I think all this superstring stuff is crazy and is in the wrong direction.
What is it you don’t like about it?
I don’t like that they’re not calculating anything. I don’t like that they don’t check their ideas. I don’t like that for anything that disagrees with an experiment, they cook up an explanation – a fix-up to say “Well, it still might be true”. For example, the theory requires ten dimensions. Well, maybe there’s a way of wrapping up six of the dimensions. Yes, that’s possible mathematically, but why not seven? When they write their equation, the equation should decide how many of these things get wrapped up, not the desire to agree with experiment. In other words, there’s no reason whatsoever in superstring theory that it isn’t eight of the ten dimensions that get wrapped up and that the result is only two dimensions, which would be completely in disagreement with experience. So the fact that it might disagree with experience is very tenuous, it doesn’t produce anything; it has to be excused most of the time. It doesn’t look right.

Asked at the end of his talk what he thought Feynman would say about string theory today, Ooguri responded with an argument that string theory had made a lot of progress since Feynman’s time, was much better understood, and was the only known consistent way to do things. He said he was very curious to know what Feynman would say, but I think it’s extremely clear what that would be: he thought it was BS back in 1987, and thirty years of lack of any progress towards making any predictions has shown that he was right back then.

I’m still an admirer of Feynman’s work and career (and sorry that I never got a chance to meet him), but at the same time think it’s a good idea to acknowledge that he, like any scientist, had his limitations. Adopting his hostility to abstract math and trying to climb Mont Blanc barefoot is likely a bad lesson to draw from his career. On the other hand, a really good lesson to learn from Feynman would be the importance of recognizing when theorists have nothing but excuses and are engaging in BS. There’s no question at all about what Feynman would have thought of the current mania for the string theory multiverse.

Posted in Uncategorized | 57 Comments

When Einstein Walked With Gödel

Jim Holt has a new book out, a collection of essays entitled When Einstein Walked with Gödel. I wrote enthusiastically about his last book (Why Does the World Exist?) here and, if you have any interest at all in the overlap of mathematics, science and philosophy, I recommend this one just as highly. Holt is pretty much a unique example of someone able to regularly write about topics in this area in a manner that is both enlightening and entertaining.

This is a book of essays written on different topics for different venues, of too great a variety to try and itemize here. Most of them have some sort of connection to mathematics and philosophy, typically centering on one idea or one, often historical, figure. Holt loves to write about the most abstract of ideas (the subtitle of the book is “Excursions to the Edge of Thought”), but in the context of the particular very human qualities of the thinkers responsible for them. For example, an essay about von Neumann and his role in the building of an early computer at the IAS includes this description:

His passion for America’s open frontiers extended to a taste for large, fast cars; he bought a new Cadillac every year (whether he had wrecked the last one or not) and loved speeding across the country on Route 66. He dressed like a banker, gave lavish cocktail parties, and slept only three or four hours a night. Along with his prodigious intellect went (according to [his second wife] Klári) an “almost primitive lack of ability to handle his emotions.”

In a short essay discussing the thorny “demarcation problem” of how to distinguish science from non-science, Holt describes briefly the ideas of Paul Feyerabend (epistemological anarchism) and Imre Lakatos (progressive versus degenerating research programs). At the same time, he includes the story of their arguments over these ideas in the context of their personal friendship:

These friendly antagonists exchanged abundant letters on the matter, with a good deal of ribaldry–some of it of a sort that no longer evokes an easy smile. “I am very tired because my liver is acting up which is a pity, for my desire to lay the broads here (and there are some fine specimens walking around on campus) is considerably reduced,” Feyerabend wrote from Berkeley. The affection between them is much in evidence…

Philosophically, however, there is no detectable convergence in their positions over their years of correspondence. That is not surprising, really, given how vexed the demarcation problem is.

One of the essays included here is a slightly edited and updated version of a review of my book and Lee Smolin’s written back in 2006 for the New Yorker (my blog post about it is here). Of the many reviews of these books at that time, Holt’s seems to me the most accurate and insightful take on the two books and the issues they were trying to address.

For a very well-executed review of the new book at the New York Times, see here. Jerry Alper has an interview and discussion of the book here.

Bonus micro-review: Another book I just finished reading is Errol Morris’s The Ashtray, which is also about philosophy and science. Morris, one of my favorite filmmakers, started out a career as a Ph.D. student of Thomas Kuhn’s, and that did not go well. For more about the book, see reviews here and here. I’ll just comment that Kuhn seems to have done the world a favor by kicking Morris out of the Ph.D. program and changing his career path to one where he could make the wonderful films he is responsible for.

Posted in Book Reviews | 3 Comments

This and That

I’ve been trying to find time to write about some books I’ve been reading. Maybe later this week. In the meantime, some things that may be of interest:

  • This week in Norway there will be various events in celebration of the 2018 Abel Prize awarded to Langlands (see here). If you want to find out the latest ideas from Langlands about geometry and the Langlands program, you better be able to read Russian, so you can read this.

    Langlands will give a lecture on Wednesday, on the geometric theory, followed by lectures from Jim Arthur and Edward Frenkel (streamed here). One would think that this would be a good opportunity for non-Russian readers to find out what Langlands is up to, but it wouldn’t surprise me if Langlands lectures in Norwegian…

    This fall the University of Minnesota will host an Abel conference, dedicated to Langlands and his work.

  • Last week the IHES hosted a conference in honor of Roger Godement. Videos of the talks are now available here. The stories of how his political engagement played out in the context of his professional life were something I had never heard about. For instance, I had missed the “Postface” (French version, English version) to one of his textbooks on analysis.
  • The Stacks Project has a new website, some discussion of the changes is here.
  • It’s the 50th anniversary of the Veneziano model and thus the birth of string theory, so various celebrations are going on this year, including this recent one. From the history as given in the talks there, no one would know that this is an idea that didn’t work out (twice, actually…).
  • There’s a very interesting interview with John Preskill at ycombinator.
  • A correspondent pointed me to the following, from a review by Alan Lightman of Carlo Rovelli’s latest, in the New York Times book review. Lightman disagrees with Rovelli on the low entropy problem of cosmology, suggesting instead that the multiverse is the answer:

    One possibility, entertained by a number of leading physicists, is that there are lots of universes, the so-called multiverse, with very different properties and initial conditions. Some of those universes may have started in conditions of maximum disorder, with nothing driving change, no distinction between future and past, where atom-size pottery shards gather themselves up to form atom-size teapots as often as the reverse. But some of these universes would have been created, by accident, with relatively high order. We live in such a universe because otherwise we wouldn’t be here to discuss the matter. The theory of “quantum gravity,” which is still not fully formulated, describes such a continuous creation of universes with random properties and initial conditions.

    Maybe I’ve missed something amidst the other multiverse mania, but the only person I’ve ever heard use “the multiverse did it” to explain this entropy problem is Sean Carroll, and it always seemed to me that he had never had any success in getting anyone to take that seriously.

Update: Glad to hear from the comment section that Carlo Rovelli “not appreciate at all the current infatuation with the idea of a multi-universe.” Unfortunately the multiverse publicity machine rolls on, with the usual nonsense, see here. I don’t agree with Sabine Hossenfelder that the problem is “over-reliance on mathematics”. What’s going wrong here is bad physics and bad science, nothing to do with mathematics.

Update: I’m glad to hear from Glenn Starkman that the Standard Model is also getting a 50th anniversary celebration soon (June 1-4), see here. Many of the talks look quite interesting, and there will be a livestream here.

Update:The Abel lectures are now online here.

Posted in Langlands, Uncategorized | 16 Comments

US HEP Budget News

There’s a HEPAP meeting today, with news about the US HEP budget situation, presentations here. Since the 2016 election physicists have been worried about how the Republican Congress and Trump administration will treat scientific research in general and physics research in particular. For instance, I see that FQXI has just announced the winners of its latest essay contest, with the second place essay by Alyssa Ney (on “The Politics of Fundamentality“) claiming that “it is easy to point to trends in allocation of research funding away from basic research in the sciences”, noting:

Another indication of the present threat to physics funding is U.S. President Donald Trump’s 2018 proposed budget. This includes a decrease of 18.4% to the Department of Energy’s high energy physics program and a cut of 19.1% to nuclear physics. The budget slashes funding of basic science at the National Science Foundation (NSF) by 13%. http://www.sciencemag.org/news/2017/05/what-s-trump-s-2018-budget-request-science

The actual enacted budget numbers for DOE HEP physics are:
FY2015 \$766 million
FY2016 \$795 million
FY2017 \$825 million
FY2018 \$908 million

It’s true that the Trump administration produced a FY2018 budget calling for a cut to \$627.7 million for DOE HEP, but that was no more to be taken seriously than anything else Trump says, and the Republican Congress instead passed a huge (10.1%) increase, to \$908 million. For FY2019 the Trump administration is calling for a DOE HEP budget cut to \$770 million (15.2% cut), but, again, no one should be taking that seriously. It’s still early in the budget process, but the House subcommittee dealing with the FY2019 DOE budget has responded to the request for a cut of 13.9% to DOE Office of Science by instead passing a 5.4% increase (it’s not yet known what the HEP part of that will be). For latest budget numbers, see here.

Over at the NSF, numbers for the Physics directorate for FY2017 are not yet available, but the enacted budget numbers for the NSF as a whole are:

FY2015 \$7,344 million
FY2016 \$7,494 million
FY2017 \$7,472 million
FY2018 \$7,767 million

The Trump administration requested a cut of 11% to NSF for FY2018, instead got a 3.9% increase. They are requesting a 3.8% cut for FY2019, the House subcommittee dealing with this instead has passed a 5.2% increase (to \$8,175 billion).

It should be uncontroversial to point out that the US budget process has been seriously broken for a while. FY 2018 started on Oct. 1, 2017. DOE HEP only recently got the \$908 million number for its budget and now is scrambling as it is “faced with a year’s worth of funding actions in around 4 months”. They’ve been spending their time preparing details of the Trump administration fantasy of how to cut 13.9% out of the FY2019 budget, instead of making rational plans for the future about how to spend the actual budget numbers they will get (OK, maybe they’re dealing with reality in secret…).

In order to avoid any misunderstanding about what I think about the current situation, my take on it is:

  • Until the 2016 election, US scientific research spending was relatively flat, due to the Obama administration’s attempt to reduce deficit spending and respond to Republican outrage at the budget deficit and demands for reductions in non-defense federal spending. We’re now starting to see large increases in research spending, as it becomes clear that whatever the current Republican party cares about, it’s not the deficit or the level of federal spending.
  • Physicists outraged at the Trump administration proposed research cuts need to realize that this, like everything else, is just theater, and understand that the current Republican party has just as little interest in cutting physics research as it ever had in reducing the deficit. Take a look at reality and stop complaining about your research funding. Fueled by huge increases in inequality in US society, truly awful things are happening in this country, but they’re not happening to you, quite the opposite. Stop whining about your science not getting enough respect and funding, and instead try and figure out what can be done to restore a healthy democracy and a more equal society.

Informed comments about HEP funding welcome, those who want to rant about politics are not. Sorry, it’s my blog, so I get to explain my point of view, even though I don’t want to engage here with the diseased post-truth reality TV show politics today’s Republican party has grotesquely exploited to come to power.

Posted in Uncategorized | 15 Comments

This Week’s (Stale) Hype

The usual hype machine is at work this week, with the usual mechanism:

Normally I try to defend the journalists involved, feeling that the most irresponsible behavior is coming from the scientists themselves. In this case, Hertog has a lot to answer for, but it’s not Hawking’s fault since he’s dead. Any semi-competent journalist should have realized that this is not news: the same stories had already been written and published a month ago, and then conclusively debunked in many places (see here, here and here for instance).

This is rather depressing, making one feel that there’s no way to fight this kind of bad science, in the face of determined efforts to promote fake physics to the public. It’s one thing for journalists to be misled by a new variant on an old debunked story, but that they’re getting misled again by exactly the same story is a new development.

Update: More hype from Hertog, this time from Scientific American, which tells us that his work is based on

string theory, one of the most dominant emerging paradigms in 21st-century physics.

Hertog is asked about the undeniable fact that his work predicts nothing:

How do you counter critics of string theory, who argue it cannot be tested?

I don’t agree with this statement; it is not my intuition that string theory can’t be tested. We may already have observations based on studies of the universe’s large-scale structure and evolution that are telling us something about the nature of quantum gravity. Of course, further theoretical work will be needed to arrive at a mathematically rigorous, fully predictive framework for cosmology.

So, your paper’s key predictions depend on the reality and nature of inflation. Will that be testable?

There are the obvious observables, yes. Just as it amplified tiny quantum fluctuations in the early universe, inflation should have amplified gravitational waves in the early universe, too. Gravitational waves are ripples in spacetime, first predicted by Einstein, that were finally observed just a few years ago—but the ones we have observed come from black holes and other stellar remnants in neighboring galaxies, not from the primordial universe. These amplified gravitational waves would leave their imprint on the polarization of the cosmic microwave background. Astronomers are actively trying to detect this polarization pattern.

So you are optimistic they will succeed?

Well, our theory certainly predicts that primordial gravitational waves should be there at some level.

As Sabine Hossenfelder points out, saying “at some level”, without even an order of magnitude estimate, is not a prediction at all. In addition, this non-prediction is exactly the same non-prediction of the theory (eternal inflation) that Hertog is claiming his work challenges.

Posted in Fake Physics, Multiverse Mania | 10 Comments

Physics News

Various physics-related news:

  • The LHC is back in business doing physics, with intensity ramp-up for the 2018 run ongoing. Today the machine is colliding 1551 bunches of protons, ultimate goal is to get to 2556 bunches. They are at least a week ahead of the planned schedule, which would have only reached 1200 bunches next week.
  • There’s a conference going on at the KITP this week, discussing the latest state of dark matter theory and experiment. By the way, see here for how prominent theorists communicate these days instead of using email…
  • At the Atlantic and Knowable Magazine, Tom Siegfried provides yet more multiverse coverage. Seems that he’s at work on a multiverse book.
  • At the Edge, Sabine Hossenfelder has an on-target analysis of the situation in fundamental theoretical physics. The problems she points to are ones that motivated books by Lee Smolin and myself back in 2006. Things haven’t improved since then and I hope she’ll have better luck generating concern for these issues than we did.
  • At Alta, Jennifer Ouellette has a fascinating account of the maneuverings for credit among the many observers of the neutron star merger last year. It sounds like some of those involved are suffering from the same disease as Brian Keating: not reality-based conviction that they’re in the running for a Nobel Prize.
  • Director Claire Denis is now at work on a sci-fi movie entitled High Life that sounds more promising than the last black hole movie. She’s getting scientific advice from Aurelien Barrau and comments:

    If there are theories about me, I’d rather not know. Astrophysics – now that’s fascinating. String theory, worm holes, the expanding universe, the Big Bang versus the Big Bounce – those are the kind of theories that make you feel like living and understanding the mystery of the world. Film theory is just a pain in the ass.


Update
: One more. David Gross will be back in Princeton this week, giving talks on gravity and particle physics. I may head down Thursday to revisit scenes of my youth.

Update: I just watched some of the KITP dark matter “debates”, see here. Highly recommended if you want to hear informative exchanges between experts on the subject, see especially the Dan Hooper talk (and the MOND/dark matter debate here).

Update: For machine learning experts who want to try their hand at an HEP data analysis problem, a Kaggle competition to build a track reconstruction algorithm opened yesterday. For details, see here and here.


Update
: Gross’s Princeton talk on the “Future of Particle Physics” was not much different than this one from a couple years ago (with the enthusiasm for supersymmetry deleted). I was thinking of writing something about this, comparing it to similar talks from way back when (see for instance here). Probably better though to wait for a better opportunity to write something substantive about where the path followed by Gross and others over the years has ended up.


Update
: Video of the David Gross Princeton talk on the Future of Particle Physics is available here.

Posted in Uncategorized | 11 Comments