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%.

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.

: 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.

: 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.

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

Posted in Uncategorized | 11 Comments

Losing the Nobel Prize

There’s a fascinating new book just now appearing in book stores, Losing the Nobel Prize, by astronomer Brian Keating. An excerpt from the book is available at Nautilus, with the title How My Nobel Dream Bit the Dust. Some reviews that are out are here, here, here and here. Sabine Hossenfelder is not too happy with the book (response from Keating here).

Much of the book is an excellent explanation, from the beginning, of a significant part of the current state of cosmology. It does a good job of even-handedly explaining the controversy over the scientific status of inflation and the multiverse, giving Paul Steinhardt’s views equal billing with those of multiverse enthusiasts like Guth and Linde. It’s written from the point of view not of a theorist, but of an observational astronomer, and thus explains well some of the details of the current state of the technology being used. Much of the book is about the BICEP telescope, operated in the hostile environment of the South Pole.

One of the strongest aspects of the book is that it is also the memoir of a life and a profession, giving a very personal take on what it’s like to get interested in astronomy as a kid, then grow up and pursue a career in the field. Keating’s book is very much in the tradition of Watson’s The Double Helix, giving a portrayal of himself and others that doesn’t leave out the very human aspects of ambition, competitiveness and jealousy.

Unlike the Watson book, which is about a great scientific achievement, the unusual aspect of Keating’s story is that what he was involved in was not a success, but the biggest fiasco in the history of his field. On March 17th, 2014, the New York Times reported on its front page that Space Ripples Reveal Inflation’s Smoking Gun, and this same story was reported by most media outlets. This was based on results from the BICEP2 telescope unveiled at a press conference at Harvard (press release First Direct Evidence of Cosmic Inflation). At the press conference, PI John Kovac claimed that the chance the results were a fluke was only one in 10 million.

I wrote several blog postings about the story as it evolved, you can find them here, here, here and here. The BICEP2 result was often portrayed as a definitive experimental vindication of the multiverse, which was one reason I was writing about it. By the later postings, I was covering the story of the collapse of the BICEP2 claims, as it became clear that what they had measured was a signal coming from dust in the galaxy, not from primordial gravitational waves.

Keating’s insider account of what happened makes clear that the true story is that the BICEP2 telescope, because of the way it was designed (sensitive to only one part of the sky at one frequency), was never capable of distinguishing primordial gravitational waves from dust. They were in hot competition with the Planck satellite collaboration, which did have the capabilities needed to distinguish the signal they were seeing from dust, and was generally assumed to be the experiment with the best chance of seeing primordial gravitational waves. BICEP2 could have released its data, making clear that it might be primordial gravitational waves or it might be dust, that Planck would need to weigh in to decide. This would have made a splash, but probably not a front-page one, and if the gravitational wave signal was real, Planck would have shared in the glory of identifying it.

Instead of behaving responsibly, the BICEP2 collaboration found arguments to convince themselves that the dust could not be a problem, arguments which included scraping data off a slide of a preliminary Planck result presented at a conference (while, it seems, misunderstanding the significance of the data in that slide). Keating gives a very defensive explanation of how this happened, claiming that he was well aware of the danger that the signal was just dust. About Planck, he writes

We desperately tried to work with the Planck team, while being careful not to tip them off as to what we’d found… The Planck team wouldn’t cooperate.

which I guess really means “we desperately tried to rip them off, but they weren’t that dumb.” While he had these concerns, in the end he decided to agree (as did the whole collaboration) with the tactic of writing a paper claiming dust wasn’t a problem and going public with an aggressive and heavily promoted discovery claim.

The cost/reward computation they were engaged in when they decided to go public with a problematic claim involved two possibilities:

  • Planck data would show the dust was not a problem. If this was the case, BICEP2 would be the people who found the primordial gravitational waves, Planck the losers who measured some boring dust.
  • Planck data would show that the signal was dust. This would be embarrassing, but, this is America, and all publicity is good publicity, right?

As far as I can tell, the BICEP2 scientists haven’t suffered much professionally from the fiasco. When David Spergel talked here at Columbia about the subject, he noted that this hadn’t stopped the PI, John Kovac, from getting tenure at Harvard. In the book, Keating mentions some “embarrassment and guilt”, but no negative professional consequences, instead explaining how a few months later Jim Simons came to him to offer to fund a next generation observational program (the Simons Observatory, of which he is now Director) to be built in Chile. The Nobel Foundation in 2015 was contacting him to request him to nominate candidates for 2016. Keating does write that he thinks the BICEP2 story shows that scientists should be given some formal training in ethical norms, but at the same time he makes clear that violating such norms sometimes provides significant rewards, with few penalties.

A major theme of the book is Keating’s obsession with the possibility of winning a Nobel Prize as well as long discussions of what’s wrong with the way Nobel Prizes are awarded and what he feels should be done about this. On some of these issues I agree with him. In particular, the Higgs discovery story makes clear the problem with awarding prizes only to individuals, not collaborations. You end up with a prize not for the most important experimental discoveries in physics, but for the most important discoveries made by experimental groups with a small enough list of high profile leaders.

Sabine Hossenfelder’s review was quite hostile about Keating’s complaints concerning how the Nobel Prize is operated, for reasons I didn’t understand until I read the book. It’s very hard to have much sympathy for Keating’s recounting of his many Nobel-related jealousies and resentments. In particular, even if there had been no dust, he was never really in the running for a piece of the BICEP2 prize nomination since he had been pushed out of a leadership role due to his involvement with a competing experiment. He still seems bitter about this and gives the impression that this is at the root of his complaints about the Nobel. One suspects that if there had been no dust and he had been given more prominence in BICEP2, after his trip to Stockholm he’d instead have written a book describing the Nobel Prize as the most well-designed and enlightened thing in the world. Instead of owning up to mistakes and writing a post-mortem about lessons learned and what to do about them, Keating’s choice to instead write a book blaming the Nobel Prize committee is a peculiar one.

Update: Keating has a Losing the Nobel Prize website, dedicated to promoting reform of the Nobel Prize along the lines suggested in his book.

Update: Not content with using notoriety achieved through incompetent and unethical scientific behavior to launch a bizarre and incoherent campaign against the Nobel Prize, Keating is taking to right-wing media outlets to attack the atheism of his fellow scientists, see here and here. I’m afraid that on the multiverse issue he has the stronger argument: multiverse proponents are making a huge mistake using that to go to war with religion.

Posted in Book Reviews | 39 Comments

Math News

Various mathematics-related news:

: This Friday and Saturday there will be a meeting in Cambridge on the topic of Ethics in Mathematics. Supposedly talks will be livestreamed on Youtube (perhaps here?).

Posted in Uncategorized | 20 Comments

Are We In the Swampland?

Way back in 2005, soon after the emergence of the “String Landscape” and the ensuing debate over whether this made string theory untestable pseudo-science, Cumrun Vafa in response started writing about the “Swampland”. In contrast to the “Landscape” of effective field theories that are low energy limits of string theory, the “Swampland” is the space of effective field theories that are not low energy limits of string theory. One motivation here is to be able to claim that string theory is predictive, since if you can show a theory is in the Swampland, then string theory predicts that theory doesn’t describe our world.

I wrote a couple blog postings about this back then, see here and here. The situation was rather comical, with Jacques Distler unintentionally making clear one problem with the whole idea. He was enthusiastic about it, and gave as one example the suggestion that one and two generation versions of the Standard Model were effective theories that could not be derived from string theory, but Volcker Braun immediately wrote in to tell him about such a derivation. At this time I started having my problems with the arXiv (and its moderator, Distler) about trackbacks, but that’s another story.

I haven’t paid much attention to the Swampland business since then, but noticed last night a new preprint with the title What if string theory has no de Sitter vacua?. The authors summarize their argument:

From this analysis we conclude that string theory has not made much progress on the problem of the cosmological constant during the last 15 years. There is a general agreement that the presence of dark energy should be an important clue to new physics. So far, string theory has not been up to the challenge. Or to be more precise, string theorists have not been up to the challenge.

The well-motivated introduction of the anthropic principle and the multiverse, was a big relief. The mathematical standards were lowered, and unconstrained model building could set in exploring a wild and free landscape of infinite possibilities. But beyond this suggestive connection between a possible multiverse and the rich mathematical structures of string theory not much solid results have been achieved. We reviewed some fraction of the mounting evidence that most, if not all of this landscape, is a swampland and we refer to [14,16,149] for similar lines of thought. We believe it makes more sense to listen to what string theory is trying to tell us, then to try to get out of the theory what one would like to have. In recent years, especially with the program of the Swampland [14, 150–152], there is luckily a growing community that embraces this idea. Perhaps this program really already made its first prediction: no measurable tensor modes in the CMB.

From what we have seen so far, we believe that the most sensible attitude is to accept there are no dS vacua at all because string theory conspires against dS vacua.

The suggestion here is basically that effective field theories on a deSitter background are in the Swampland, so can’t be derived from string theory. Since we seem to live in a deSitter space, the obvious conclusion to draw from this is that string theory is falsified: it can’t be the fundamental theory we are looking for. The authors discuss various unconvincing ways to try and avoid this conclusion.

By the way, the authors make the usual flawed argument that “the string theory landscape is just like the Standard Model”:

This kind of criticism is, however, misguided [10, 11]. One might compare with quantum field theory, where there is an infinity of fully consistent theories. Experiments are needed to pick the right one, and parameters must be fitted. When this is done the theory still has enormous predictive power, and no one would claim that the Standard Model is useless. One could argue in a similar way concerning the string landscape.

They also claim:

Paradoxically the critics of string theory and the proponents of the string landscape all agree on one thing: the landscape exists and we more or less know its properties.

At least this string theory critic has never agreed on this. I don’t believe “string theory” is a well-defined enough framework to answer the question of what all its ground states might be, or to properly characterize them. If you accept conjectures about the theory put forward by the landscapeologists, all evidence is now that the set of ground states they identify is so large as to make predictions impossible. The argument against string theory is that there are two possibilities here: either the theory is too poorly understood to tell us what its ground states are, or it does tell us something, and there are too many ground states to make useful predictions. Either possibility leads to the same conclusion that this is a failed idea.

It is rarely acknowledged just how serious the problem of a lack of a definition of “string theory” really is. To get some idea of how bad this problem is, one can consult one of the main references in this paper, a survey of the Landscape and the Swampland, based on Vafa’s 2017 TASI lectures (this paper also discusses the idea that deSitter is not in the Swampland). Claims are often made that AdS/CFT resolves the problem of defining a non-perturbative string theory of quantum gravity, but in the paper one finds:

We can now ask the question if using this AdS/CFT correspondence gives a non-perturbative definition of string theory. The motivation for this is that we can give a non-perturbative definition of SYM theory, for example by lattice regularization, whereas the holographic quantum gravity dual theory in AdS has no complete definition. The fact that the CFT side, i.e. the non-perturbative definition of SYM, gives in principle, a non-perturbative definition of the AdS side, is of course true. But this may be not very useful for deeper questions of quantum gravity. In fact the regime that the gravity side is weakly coupled is big corresponds to when the SYM is strongly coupled. In fact ‘t Hooft was trying to use string theory as a solution to the gauge theory question at strong coupling and not the other way around!…

we find ourself back at the beginning: we want to know fundamentally, what is quantum gravity? It should describe the quantum fluctuations of the metric. From a brief analysis of the standard Einstein-Hilbert action, we see that fluctuations of the metric at the Planck scale should become very violent, leading to potential changes in the topology of the spacetime [103, 104]. This leads naturally to the idea that quantum gravity should be equivalent to summing over all spacetime topologies and geometries:
$$Z_{QG} \sim \sum_{\text{top. and geo.}} e^{-S}$$
In general we have no idea about what description will lead to the correct sum over geometries and topologies. We only do know that there should be some mechanism that washes out the Planck scale fluctuations to produce a smooth space at lower energies. It seems that this description must come from some new fundamental principle, rather than from some duality such as mirror symmetry or AdS/CFT. This lack of knowledge of describing the gravity side quantum mechanically is “the missing corner” in our understanding of string theory.

In both this survey and the new paper, the tactic of trying to remove the Landscape to restore the predictivity of string theory hits up against the obvious problem: you’re left with no theory at all (the equation above, with an undefined sum and an undefined action, is the essence of no theory).

Posted in Swampland | 21 Comments