Not Even Wrong

Some assorted things I’ve run across recently that may be of interest:

Talks from the annual meeting of the SLAC Users Organization.

A dialogue between Barry Mazur and Peter Pesic about imagination and mathematics.

An Op-Ed piece in today’s New York Times by my colleague Brian Greene called That Famous Equation and You.

Some sensible comments by John Baez about string theory.

A survey of the state of string field theory by Leonardo Rastelli.

A “description of some important issues in supersymmetry and string phenomenology” entitled Twenty-five Questions for String Theorists. The authors think these questions may have answers that will help connect string theory and phenomenology, although this seems to me unlikely. Serkan Cabi also has some comments on this paper.

An article about Feynman by Freeman Dyson in the latest New York Review of Books.

A talk about theoretical physics in the Netherlands.

Update: One more, a report by Paul Cook on an interesting talk by Roman Jackiw.

Zvi Bern gave a talk yesterday at the KITP in Santa Barbara entitled The S-Matrix Reloaded: Twistors, Unitarity, Gauge Theories and Gravity. He surveyed recent progress on computing perturbative amplitudes in QCD and N=4 supersymmetric Yang-Mills, some of which involves using twistor methods. The most striking thing though were his last few transparencies (here, here, and here). He notes that all previous studies of divergences in supergravity rely only on power-counting and supersymmetry, assuming that if these two principles allow a divergence to occur, it will. Actually doing the full computation to see if the divergences are there is too hard and no one has done it. Bern notes that in these arguments the extra structure seen by the recent twistor methods is not taken into account, and when one does this, so far all complete calculations show that N=8 supergravity has exactly the same degree of divergence as N=4 Yang-Mills, even though one would naively expect the supergravity amplitudes to have worse behavior. He ends by suggesting that “Serious re-examination of the UV properties of multi-loop N=8 supergravity using modern tools is needed.”

If N=8 supergravity turns out to be renormalizable, this raises an interesting question about string theory….

The International Congress of Mathematicians (ICM) takes place every four years and is the most important international conference in mathematics. The 2006 ICM will take place next August in Madrid. One thing that happens at each ICM is the announcement of the winners of the Fields Medal. This has traditionally been considered the most prestigious award in mathematics, and the closest analog to a Nobel prize in math, although the recently instituted Abel prize may now compete for this honor. The Fields medal is awarded to between two and four people at each ICM, and recipients must be under the age of 40 on Jan. 1 of the year of the ICM. I have no inside information about who will win this year, but in gossip with mathematicians two names that tend to come up are those of Grigori Perelman (for his work on the Poincare conjecture), and Terence Tao.

The other important thing about the ICM is the list of invited talks. The speakers are carefully chosen and are supposed to be people who have done the most important work in mathematics during the past four years. Looking over the list of speakers gives a good idea of who the most prominent names in the business are, as well as what are the hottest topics. It’s an especially great honor to be chosen as a plenary speaker, and the names of these have been recently announced. The invited speakers in the various sections have also been announced, one section covers mathematical physics.

Philip Anderson has a piece in the latest Nature entitled Thinking Big. It’s about the interpretation of quantum mechanics, and in it he claims that Fritz London was the first one to really have the right idea about the problem. Commenting on the Bohr-Einstein debates on the subject, Anderson says “In reading about these debates I have the sensation of being a small boy who spots not one, but two undressed emperors.” Instead of the Bohr or Einstein positions, Anderson promotes a point of view he attributes to London, who wrote a paper about it in 1939 with Edmond Bauer. He says “Taking London’s point of view, one immediately begins to realize that the real problem of quantum measurement is not in understanding the simple electron being measured, but the large and complicated apparatus used to measure it” and that “The message is that what is needed is an understanding of the macroscopic world in terms of quantum mechanics.”

I take Anderson’s point to be that the classical physics of a measuring apparatus is an “emergent phenomenon”, and understanding this is the real problem of interpreting quantum mechanics. He ends with his favorite slogan: “more is different!”.

The science magazine Seed is being relaunched, and the first issue of its new incarnation is now on the newsstands. Their motto is “Science is Culture”, and Clifford Johnson over at Cosmic Variance has an enthusiastic appreciation of what they are doing. The magazine is strikingly attractive, with impressive photography and graphics. One photo essay pairs photos with important equations.

There’s a piece by Lisa Randall promoting her recent work with Andreas Karch on what she calls the “relaxation principle”. I guess this is meant to be a sort of vacuum selection principle, contrasted to the “anthropic principle”. In her Seed article she describes what she is doing as follows :

The challenge for physicists, and the problem I tackle in my own work, is find all possible qualitatively different universes — and to search for principles that determine which of these universes is most likely to exist.

Unfortunately there seem to be an infinite variety of possible such universes, and examining them all could easily take up the efforts of all particle theorists for the next few centuries. There’s zero evidence for any sort of vacuum selection principle that will pick out the standard model from this infinite array of possibilities, so setting out on this path means probably abandoning any hope for ever explaining much of anything about particle physics. Karch and Randall try to give an argument for why there are 3 space dimensions, ending up with an argument for the survival of both 3 and 7 dimensional branes if one starts out with branes of all dimensions. This is a very, very long way from getting any non-trivial information about particle physics.

This issue of the magazine also has a short piece entitled “A New Force? How blogs are revolutionizing physics” by Joshua Roebke, an ex-string cosmology graduate student who now works at Seed. Joshua devotes a sizable part of his piece to telling about “Not Even Wrong” and some of the effects it has been having. Earlier this summer I had lunch with him here in New York and was encouraged to see that Seed has someone on staff with a good theoretical physics background.

Update: Lubos Motl also has a posting about the new Seed magazine. He comments on the Karch-Randall “relaxation principle”, saying that he “kind of worked on it”, but

frankly, I don’t really believe it – because of the devil hiding in the details that just don’t seem to work – much like many other proposals that have appeared in recent years.

Via For God, for Country and for Your Name Here, it seems that Alan Guth had the winning entry in a Boston contest for the messiest office. He won an office make-over, check out the before and after photographs.

There’s an interesting article by Graham Farmelo in last week’s Nature, entitled Dirac’s Hidden Geometry. Most people think of Dirac as a brilliant algebraist, but he himself claimed that his motivations and way of thinking were much more geometrical than algebraic. Farmelo’s article contains an amusing account of how Roger Penrose tried to get Dirac to explain how projective geometry had influenced his work in quantum mechanics. Dirac gave a talk about this at Boston University in 1972, but, after giving a presentation about projective geometry, stopped before explaining the relation to quantum mechanics. Penrose, the moderator, asked Dirac about the relation to quantum mechanics, and in answer “Dirac gave his trademark shake of the head, and declined to speak.”

Several historians of science have tried to figure out what Dirac’s geometrical motivations were. This question is dealt with in Olivier Darrigol’s very interesting book (which is now available on-line) From c-numbers to q-numbers: The Classical Analogy in the History of Quantum Theory. The material about Dirac and projective geometry is in chapter XI. On the same topic, there’s also an article by Peter Galison published in 2000 in the journal Representations, entitled The Suppressed Drawing: Paul Dirac’s Hidden Geometry.

After my initial success last year, I’ve retired from the business of predicting who will get Nobel prizes. This year’s physics prize will be announced in less than two weeks, on Tuesday, October 4. Anyone else want to make a prediction?

Last year there was a Nobel Prize Market, but it doesn’t seem to be in operation this year.

For the last few years Thomson Scientific has been issuing Nobel prize predictions based on citation counts. They’re not doing very well in physics, basically because every year they predict it will be Green, Schwarz and Witten. This year’s prediction is here. In 2003 they rather petulantly commented:

Most observers believe the Nobel Prize will not be awarded for theoretical work. If, however, citations reflect real influence and prizes ought to be awarded for influential work, the Nobel Committee should consider recognizing string theory and M theory, whose leading figures have been Green and Schwarz, the pioneers, and Witten, who extended their work. Witten, it should be noted, is the most-cited physicist of last two decades.

Their idea that the Nobel prize is not awarded for theoretical work is kind of strange, and wrong. Last year’s award was to theorists. The people at Thomson seem to not be able to tell the difference between theoretical work that is confirmed by experiment, and work which isn’t. So far the Nobel committee seems to be able to make that distinction, and doesn’t just count citations. Presumably this will still hold true for this year. While I won’t predict who will get the prize, I will predict that Green and Schwarz won’t get it, and if Witten does, it won’t be for his work on string or M-theory.

A correspondent points out to me that the latest issue of American Scientist has a wonderful review of Roger Penrose’s new book The Road to Reality by computer scientist, author, artist, etc. Jaron Lanier, much better than my own effort along these lines. Despite not being a theoretical physicist, Lanier does a great job of recognizing and explaining what is great about Penrose’s book. He also is dead-on about string theory (“mob mentality”, “pompous triumphalism”).

The same issue of American Scientist also has a very good review by Lee Smolin of Gravity’s Shadow: The Search For Gravitational Waves by Harry Collins. It also contains a nowhere near as good review by yours truly of Sneaking a Look at God’s Cards, a book about interpretational issues in quantum mechanics by Giancarlo Ghirardi.