Not Even Wrong

Adrian Cho at Science magazine this week has an article about Craig Hogan’s project to build a “holometer” and somehow test the “holographic principle”. Since this promises some sort of experimental test of fashionable ideas about quantum gravity, it has gotten a lot of attention, including a cover story in the February Scientific American (also available here and maybe elsewhere).

This kind of thing often gets promoted as a “test of string theory”, but in this case, at least from certain quarters, that definitely isn’t happening. Cho quotes Raphael Bousso:

But some experts on the holographic principle think the experiment is completely off-target. “There is no relationship between the argument [Hogan] is making and the holographic principle,” Bousso says. “None whatsoever. Zero.” The problem lies not in Hogan’s interpretation of the uncertainty relationship, but rather in “the first step of his analysis,” Bousso contends.

Bousso notes that a premise of special relativity called Lorentz invariance says the rules of physics should be the same for all observers, regardless of how they are moving relative to one another. The holographic principle maintains Lorentz invariance, Bousso says. But Hogan’s uncertainty formula does not, he argues: An observer standing in the lab and another zipping past would not agree on how much an interferometer’s beam splitter jitters. So Hogan’s uncertainty relationship cannot follow from the holographic principle, Bousso argues.

The experiment can do no good in testing the holographic principle, Bousso says, but running it could do plenty of harm. The holometer has garnered an inordinate amount of attention in the blogosphere and in press accounts, he says, raising unrealistic expectations. “They’re not going to have a signal and then there is going to be a backlash saying that the holographic principle isn’t valid, and we’ll look like we’re on the defensive,” Bousso says. “That’s why I’m trying to get the word out [that the experiment won’t test the principle] without appearing to make excuses.”

There’s also the following from Lenny Susskind:

Not everyone cheers the effort, however. In fact, Leonard Susskind, a theorist at Stanford University in Palo Alto, California, and co-inventor of the holographic principle, says the experiment has nothing to do with his brainchild. “The idea that this tests anything of interest is silly,” he says, before refusing to elaborate and abruptly hanging up the phone.

I just noticed that the Templeton Foundation has a competition for $5 million in grants in the area of “strong emergence”, submission deadline very soon (April 16). I’m not sure I understand their distinction between “weak emergence” and “strong emergence” (classical phase transitions are weakly emergent, quantum ones strongly emergent), but they seem to intend to support real physics research, and they’re inspired by Philip Anderson’s wonderful paper More is Different. This is a refreshing contrast to some of their other ventures I’ve written about here that tend towards encouraging pseudo-science, so I hope this one is a success and they do more things like it.

Their other current funding opportunity, also with a deadline of April 16, is Breaking New Ground in Science and Religion, which is more the usual kind of thing for them. They don’t give a total number for what they intend to spend in this area, but it appears to be much less than the $5 million going to emergence.

In this week’s Nature, Abraham Loeb, the chair of the Harvard astronomy department, has a column proposing the creation of a web-site that would act as a sort of “ratings agency”, implementing some mathematical model that would measure the health of various subfields of physics. This would provide young scientists with more objective information about what subfields are doing well and worth getting involved with, as opposed to those which are lingering on despite a lack of progress. Guess what Loeb’s main example is of the “lingering on” category?

In physics, the value of a theory is measured by how well it agrees with experimental data. But how should the physics community gauge the value of an emerging theory that cannot yet be tested experimentally? With no reality check, a less than rigorous hypothesis such as string theory may linger on, even though physicists have been unable to work out its actual value in describing nature…

Theory bubbles

The study of the cosmic microwave background provides an example of how theory and data can generate opportunities for young scientists. As soon as NASA’s Cosmic Background Explorer satellite reported conclusive evidence for the cosmic microwave background temperature fluctuations across the sky in 1992, the subsequent experimental work generated many opportunities for young theorists and observers who joined this field. By contrast, a hypothesis such as string theory, which attempts to unify quantum mechanics with Albert Einstein’s general theory of relativity, has so far not been tested critically by experimental data, even over a time span equivalent to a physicist’s career.

The problem of course is that of deciding who gets to make evaluations of what’s a healthy field and what isn’t. People with a lot invested in a dying or dead subject have strong incentives to misrepresent the situation (see, for example, the famous Monty Python Dead Parrot sketch). Loeb implicitly compares the current situation with string theory to that following the financial crisis, which was worsened by the ratings agencies assigning AAA ratings to debt not far from default.

Senior scientists might seem the people best suited to rate the promise of research frontiers. But too many of these physicists are already invested in evaluating the promise of these speculative theories, implying that they could have a conflict of interest or be wishful thinkers. Having these senior scientists rate future promise would be akin to the ‘AAA’ rating that financial agencies gave to the very debt securities from which they benefited. This unseemly situation contributed to the last recession, and a long-lived bias of this type in the physics world could lead to similarly devastating consequences — such as an extended period of intellectual stagnation and a community of talented physicists investing time in research ventures unlikely to elucidate our understanding of nature — a theory ‘bubble’, to borrow from the financial world.

The problem of how to get scientists and academics to rigorously evaluate what works and what doesn’t is a difficult one. In particle physics, success has led to making progress harder to come by, so just noticing a lack of progress at the rate of earlier times is not enough. String theorists are right to point out that developing ideas to the point that the theory can be compared usefully to experiment could be a difficult goal that may take a long time to get to. They’re wrong though not to acknowledge the fact that they’re not getting closer, but rather farther and farther away. And misrepresentations about the state of a subject can victimize young students and researchers, induced to devote crucial parts of their lives to something not worthwhile.

I’m rather skeptical about Loeb’s faith in mathematical models to provide objective guidance. The AAA ratings assigned to dubious mortgate-backed securities were the product of mathematical models, defective ones. If you let me design the model, I can come up with one that will justify whatever conclusion I want. In the end, outcomes will depend on the quality of the judgment and decisions of those the community chooses as its leaders. Throughout academia, bad ideas live on, and good ones don’t get the recognition they deserve. At the same time, in many fields those put in positions of responsibility live up to them and often do a remarkable job of countering the forces promoting stagnation as well as providing a positive vision that drives real progess.

As for Loeb’s idea about a web-site where young scientists could go to get information about the health of a field, I remain skeptical about prospects for one that implements a mathematical model. However, a website devoted to honest and informed discussion about what is going on in a field and whether it is healthy, providing a place for students and others to listen to and participate in debate, helping them make up their own minds, seems to me an excellent idea…

Update: I just noticed that Loeb had a paper on the arXiv last year spelling out his proposal in more detail.

A report from India:

‘CERN need not spend so much on LHC experiment’

Father of String Theory and noted physics scientist Holger Bech Neilsen of Denmark has said that contributions from the Large Hadron Collider (LHC) at CERN are over-rated and that there is no need for spending so much on the experiment.

Interacting with the students and faculty of National Institute of Technology (NIT), Warangal, here on Monday, Prof. Neilsen said that he discouraged spending huge funds on such research projects.

When asked how he would justify the need for unification, considering the fact that individually theories such as quantum mechanics and gravitation have been showing good results, he said that there was no ardent need for a unified theory of everything but that such a theory would bring about new perspectives of understanding the world around us.

Prof. Neilsen who was nominated twice for the Nobel Prize was here at NIT on a two-day visit at the invitation of the students.

The picture with the article show a blackboard where Nielsen has been explaining superstring theory to the students. The talk supposedly was on April 2, so presumably this wasn’t an April 1 performance. I guess he’s right: since string theory says nothing about LHC physics, the machine is kind of pointless.

Update: A commenter points to this video interview with Nielsen made during his trip to India.

This week at Caltech there’s a workshop celebrating the 35th anniversary of N=4 Super Yang-Mills theory. George Musser of Scientific American is covering the workshop here. He reports that N=4 Super Yang-Mills is being describe as the “Darth Vader theory”, I guess by Nima Arkani-Hamed. The conjectural 6d (2,0) superconformal theory gets called “the Emperor Palpatine of theories”.

Perhaps slides from the talks will be posted at some point. Witten will close the workshop tomorrow with a talk not about Darth Vader or the Emperor Palpatine, but about “Superstring perturbation theory revisited”.

Update: Clifford Johnson reports on the conference here.

Update: Someone at the conference confirms that the “Darth Vader” description came from Arkani-Hamed, who in his talk said something like:

“The relation between 4D N=4 SYM and the 6D (2, 0) theory is just like that between Darth Vader and the Emperor. You see Darth Vader and you think “Isn’t he just great? How can anyone be greater than that? No way’.Then you meet the Emperor”.

Update: A couple reports from the conference banquet. During his presentation Dan Freedman unveiled his new textbook on Supergravity (see here) and offered to sell copies to those attending the conference at 20% off. Stephen Hawking was there. He’s in Pasadena for his yearly visit and to appear in an episode of “The Big Bang Theory”. The show’s writers and producers are very excited about the “Darth Vader/Emperor Palatine” thing and planning on working it into the show’s script. Afterwards Hawking invited many people to join him and some of the cast of the show on a trip out to his favorite club in San Bernadino.

Update: Given that the previous update was written on April 1, readers might want to have some suspicions about whether it is completely accurate.

Update: Some slides from the talks are now available here.

Theoretical physics, as practiced in the mainstream media, seems to be moving from a mania about multiverses to a religious battle over nothingness. On one side we have physicist Lawrence Krauss, with his best-selling new entry into the atheism book sweepstakes: A Universe from Nothing. Krauss is backed by Richard Dawkins, who compares the book’s devastating effect on religion to that of Darwin’s.

On the other side we have philosopher David Albert, backed by a million dollars from the Templeton Foundation (see more here), who has a review out this morning in the New York Times characterizing Krauss as “pale, small, silly, nerdy” (his ideas, not him, I think).

The big debate here is over what one means by “nothingness”, which seems to me characterizable as nothing of interest. I guess though that there is a lot of money to be made in the nothingness business. The next opportunity for a big payday from nothingness will be on Thursday, 11 AM GMT, when Templeton will announce who gets this year’s $1.7 million dollar prize. I’ve no idea who will get it, just that it won’t be Krauss.

In the years before the LHC start-up, one heavily promoted claim that “yes, string theory can too make predictions, and here’s what it predicts the LHC will see” was based on a class of models known as “F-theory”. Detailed superpartner mass spectra were produced and shown around the world at conferences and departmental colloquia. For an example, take a look at figures 3 and 29 of this paper.

Early LHC results showed that nothing like these mass spectra corresponds to reality. For the latest such results, see Resonaances, which describes new SUSY limits from ATLAS, now wildly out of agreement with the F-theory “predictions”.

At this week’s F-theory Workshop, there seems to have been little acknowledgement of this failure. I didn’t notice either any reference to the fate of the “predictions”, or even an attempt to come up with new, updated ones. The closest I could find was this comment by Michael Dine in a discussion of the state of F-theory phenomenology”:

A lot of us I think are resigned to the idea that maybe there’s supersymmetry and it’s going to look tuned, or maybe there’s not low energy supersymmetry. I think a challenge I’ve always said for string theory is to try and think about theories without supersymmetry and that has proven to be hard. But you know, that’s certainly a direction which maybe we’re being confronted with.

So, the long-standing ideology that supersymmetry stabilizes the weak scale, and seeing its effects will finally give evidence for string theory unification looks like it is crumbling. With this hope gone, string theory unification becomes a completely unpredictive subject, with no hope of connection to experiment. One has an infinite array of mathematically highly complex models one can spend time studying, but it’s hard to characterize doing so as any recognizable form of physical science.

This situation hasn’t slowed down string phenomenologists, who will follow up the F-theory workshop with a summer school for graduate students to train them in the failed techniques of the subject. I have a hard time understanding why any sensible graduate student would want to attend such a thing, or why any responsible advisor would encourage them to do so.