Not Even Wrong

Stanford University will officially announce later today the founding of a new research institute, with major funding from the John Templeton Foundation. Many of the faculty and research staff of the new institute will come from the present Institute for Theoretical Physics which will be shutting its doors.

Co-directors of the new institute will be Stanford faculty member Leonard Susskind, and Gerald Cleaver, who is currently head of the Early Universe Cosmology and Strings Group at Baylor University. Susskind, who is one of the co-discoverers of string theory, has in recent years been the most prominent promoter of the theory of the “multiverse”, which he describes in a recent interview. Later this month he will be giving the Einstein lecture at Brown University on the topic of String Theory and Intelligent Design. He is widely considered to be the leading candidate for next year’s Templeton Prize. Cleaver, a prominent string theorist who was a student of John Schwarz (the co-discoverer of superstring theory) at Caltech, has published more than 40 important research articles on string theory. Like Susskind, his recent interests have been in the area of string cosmology.

Next year the institute will open its doors with a year-long program on the topic of the multiverse, led by theoretical cosmologist George F. R. Ellis visiting from the University of Cape Town. Ellis, the 2004 Templeton Prize winner, explains that the traditional view of an opposition between faith and science has been made obsolete by the latest research in string theory and cosmology. Says Ellis, “In the end, belief in a multiverse will always be just that — a matter of belief, based in faith that logical arguments proposed give the correct answer in a situation where direct observational proof is unattainable and the supposed underlying physics is untestable.”

The new institute will be named the Stanford Templeton Research Institute for Nature, God and Science (STRINGS) and will collaborate with other related Bay Area organizations, including Stanford’s own KIPAC (Kavli Institute for Particle Astrophysics and Cosmology) and Berkeley’s CTNS (Center for Theology and the Natural Sciences). Steve Kahn, the director of KIPAC, welcomed the formation of the new institute saying “We’re very pleased to have such a major institution on campus led by two such prominent physicists working on cosmology. In this era of declining NSF and DOE budgets, we need to branch out from traditional approaches to science. We expect to collaborate with the new institute to help us seek funding from sources such as the President’s FBCI initiative.” Besides the physicists, several faculty from other Stanford departments will be affiliated with the Templeton institute, including computer scientist Donald Knuth, author of the recent book Things a Computer Scientist Rarely Talks About.

According to Dr. John M. Templeton, Jr., president of the Templeton foundation, “the idea for the institute grew out of our involvement with a series of lectures at Stanford in the area of biology. At those lectures the biologists pointed out to us that it was the physicists on campus who were doing work most closely related to our foundation’s interests, something we had already noticed through our Cosmology and Fine-tuning Research Program. As the latest cutting-edge research in physics has caused physicists to rethink what it means for a theory to explain experimental data, the wedge driven by Galileo between science and religion has begun to close. We’re very proud to be able to support and encourage this trend.”

Encouragement also comes from some other members of the Stanford physics department. Nobel-prize winning theoretical physicist Robert McLaughlin was quoted as saying “theoretical particle physics is just getting old and losing its youthful good looks. Even Ed Witten has given up on it. This latest plan for the cosmology/multiverse/string theory crowd to join up with Templeton reminds me of a woman deciding to become a nun when she gets too old to attract men. But if it gets them out of the physics department, I’m in favor of it. Don’t let the door hit you on the way out, guys.”

The Perimeter Institute in Canada is known as a center for research in Loop Quantum Gravity. This week they have come up with an extremely clever way to make string theorists look bad. They’ve scheduled a week of talks on String Phenomenology, ending this Friday on April Fool’s day. Most of the talks are related in one way or another to the “Landscape”, with talks by Kachru on “Landscape Architecture” and DeWolfe on “More Landscape Architecture”. If you’re in the mood for a giggle, tune into these talks tomorrow: it will be all landscape, all the time, from Michael Douglas in the morning to a panel discussion in the evening moderated by Herman Verlinde on the topic “Landscape: What Is It Good For?”. It’s quite possible the panel discussion will be very short.

John Baez has just put out a new issue of his This Week’s Finds in Mathematical Physics, dealing partly in more detail with the material about Clifford modules mentioned here a couple weeks ago. I’ve added as the first comment here something he had some trouble submitting as a comment to the older posting on this topic.

John briefly mentions a relation of all this to Bott periodicity in topology, using a very abstract homotopy construction involving spectra. A more concrete version of this can be found in Milnor’s book on Morse theory. For the relation of Clifford algebras and K-theory, the standard refererence is the 1964 paper “Clifford Modules” by Atiyah, Bott and Shapiro published in the journal “Topology”. The crucial fact they describe is how the Thom isomorphism in K-theory (which is essentially the same fact as Bott periodicity) is related to the structure of Clifford modules. Greg Landweber has recently worked out an interesting equivariant version of this story.

Greg also has a nice new paper with Megumi Harada about the K-theory of a symplectic quotient, that looks like it should imminently appear on the arXiv.

John also mentions some recent work of Dror Bar-Natan, Thang Le and Dylan Thurston on the Duflo isomorphism. This is a beautiful story, and also has a relation to Clifford algebras that John doesn’t mention. For this, see Eckhard Meinrenken’s talk at the 2002 ICM in Beijing.

Last week the 2005 International Linear Collider Workshop was held at SLAC, and the talks are available on-line. At the conference it was announced that Barry Barish of Caltech would lead the Global Design Effort for the International Linear Collider. The hope is to finish a design for the ILC in 2007, have a site chosen in 2008 and construction done by 2015, allowing the ILC to run at the same time as the LHC for several years, with each machine providing data that could help decide how best to use the other one.

This schedule seems overly optimistic to me. Because of the huge US deficits, getting the kinds of increases in the DOE budget needed to build the ILC in the US looks quite difficult, and, even if this were possible, funding constraints would probably stretch out the construction schedule. In Europe, CERN is devoting all its resources for a while to the LHC, and is backing an alternate, more speculative linear collider technology called CLIC. The most likely course of events seems to be that people will be waiting to see what the LHC finds and how the CLIC technology works out before fully committing to a new linear collider. If so, a decision about what to build and where to build it would probably not take place until almost 2010, with another decade probably required to actually construct the machine.

At the SLAC conference, the main theoretical talk was one by Savas Dimopoulos on New Models about his work with Arkani-Hamed on split supersymmetry and models where both the cosmological constant and the weak scale are anthropically determined aspects of the “Landscape”. There increasingly seems to be a disconnect between the experimentalists planning experiments at the LHC and ILC, whose plans often revolve around the search for low-energy supersymmetry, and the string theory inspired theorists, who are spending their time wandering around the landscape. From the landscape point of view, it seems that low-energy supersymmetry is extremely unlikely.

For more from theorists wandering around the landscape, see the talks at this week’s Workshop on N=1 Compactications at the Fields Institute in Toronto. The talks from this workshop are starting to become available on-line. Next week there will be even more of this at the Fields Institute, as it hosts a Workshop on String Phenomenology.

It’s now been exactly one year since I first set up this weblog. At the time I thought the number of those sharing my interests would be very small and hardly anyone would be looking at whatever I put up here. Things have turned out very differently, with an ever increasing number of connections. I started gathering statistics in May of last year. Here’s the average number of connections to the main page per day (there’s a similar number of connections to other pages, from Google searches and links from elsewhere).

May 2004 146
June 2004 240
July 2004 281
August 2004 336
September 2004 315
October 2004 514
November 2004 514
December 2004 572
January 2004 735
February 2005 955
March 2005 (first half) 1109

I’ve enjoyed and learned a lot from many of the comments posted here (at last count there have been 2728, concerning 168 different postings), but a recurring problem has been that many people would like to turn the comment section into a discussion forum for their own personal speculative ideas about physics. This threatens to completely overwhelm discussion of the topics I’m actually posting about. This morning I had to delete several several such comments from different people. Please do not post comments here of this kind. Get your own weblog and do it there. If every so often you want to post a link here to something you’ve written of this kind elsewhere, that’s fine.

It’s been quite a year, especially as the story of string theory just gets weirder and weirder. I have no idea what will happen during the next year, but I’m looking forward to finding out.

A paper appeared on the arXiv last night entitled Primordial Inflation Explains Why the Universe is Accelerating Today by Rocky Kolb of Fermilab, together with Sabino Matarrese, Alessio Notari and Antonio Riotto. There’s also a Fermilab press release about it today.

I’m no expert on the subject, and would love to hear the opinion of someone who is. As near as I can figure out the idea is that what is really responsible for the effects that have been ascribed to a cosmological constant is a “cosmological perturbation” of the gravitational field. This is supposed to be a perturbation that expanded during the inflationary period so that its wavelength is now larger than the Hubble radius. According to the authors, this predicts a different magnitude vs. red-shift relation than the standard cosmological constant does, so their idea should in principle be testable.

If they’re right, this certainly will cause a huge problem for the whole “Landscape” business, which has advertised as its greatest success the “prediction” of a non-zero cosmological constant of the right order of magnitude.

Today’s San Francisco Chronicle contains an article about string theory entitled “Theory of Everything” Tying Researchers Up In Knots. It’s by science writer Keay Davidson, and is about the most skeptical article on string theory I’ve seen in the mainstream press. The lead sentence is:

“The most celebrated theory in modern physics faces increasing attacks from skeptics who fear it has lured a generation of researchers down an intellectual dead end.”

Davidson contrasts Michio Kaku’s very pro-string theory point of view in his new book Parallel Worlds, with the much more skeptical views of Lawrence Krauss, who evidently has a book entitled “Hiding in the Mirror: The Mysterious Allure of Extra Dimensions” coming out in September. He also got comments about the current state of string theory from quite a few different people, including yours truly. The article contains a link to this weblog.

Some of the string theory critics quoted are just inherently opposed to any new mathematical approach to fundamental physics, something I have no sympathy with. One of these is Stanford’s Robert Laughlin, who makes the point that string theorists are trying to camouflage the theory’s increasingly obvious flaws by comparing the theory to “a 50-year-old woman wearing way too much lipstick.” Because of Laughlin’s extreme anti-mathematical theory views on the one side and those of his colleagues like Lenny Susskind on the other, “The physics department at Stanford effectively fissioned over this issue” says Laughlin. He goes on to say “I think string theory is textbook ‘post-modernism’ (and) fueled by irresponsible expenditures of money.” For the record, I’m no more of a fan of Laughlin’s views about particle theory than I am of Susskind’s.

Some of the quotes from defenders of string theory are a bit strange, with none of them addressing the fundamental problem the theory is facing these days as it becomes obvious that it can’t predict anything. John Schwarz is quoted as saying “string theory is the only approach that has the potential for explaining dark energy” which is kind of peculiar since it is well-known that superstring theory naturally leads one to expect a value for this energy density that is off by 120 orders of magnitude. The only way around this seems to be the “landscape” argument, in which you essentially give up any hope of ever predicting anything. The other defenders of string theory quoted in the article mainly try and claim that twenty years of work on the theory is still nowhere near enough, that it is way too early to be able to evaluate it yet. They don’t give any indication of how much longer we should wait for such an evaluation, but if twenty years isn’t long enough, it sounds like they hope this won’t occur while they’re still alive.

Update: For a very different take on this, see Lubos Motl’s posting.

John Baez had a weblog long before the term was even invented, and for many years now has been consistently putting out interesting current material about math and physics under the title This Week’s Finds in Mathematical Physics. The latest edition has a beautiful explanation of the structure of modules of the Clifford algebra.

Traditionally one thinks about geometry in n-dimensions in terms of n-dimensional vectors and tensors built by taking tensor products of vectors. These are all representations of the general linear group GL(n), or if one has a metric, the othogonal group SO(n) of transformations that preserve the metric. However, it turns out that there are representations more fundamental than vectors, the spinor representations. These require a metric for their definition, and are projective representations of SO(n), or true representations of the double-cover Spin(n). When one tries to construct spinors, one quickly runs into a fundamental algebraic structure associated with a real n-dimensional vector space: the Clifford algebra C(n). Spinors occur as “modules” of the Clifford algebra, i.e. vector spaces that the Clifford algebra acts on. The structure of these possible Clifford modules is rather intricate, with a certain eight-fold periodicity. Baez gives a beautiful explanation of part of this story.

Physicists generally complexify everything in sight (i.e. assume all numbers are complex), which makes things much simpler. Then the story is periodic with period 2 instead of 8, and Clifford algebras are just one or two copies of a complex matrix algebra of k by k matrices, where k is some power of 2. Clifford modules (including the spinors) in this case are just complex vector spaces of dimension k, and tensors built out of these. One good place to read about all this, together with its relation to the index theorem, is in the book “Spin Geometry” by Lawson and Michelson, but there are by now lots of others.

If one believes in a deep relation between physics and geometry, these Clifford modules should somehow come into play in the structure of the most fundamental physical theories. To some extent this is already in evidence in the way spinors and the Dirac operator occur in the standard model. There are also tantalizing relations between the idea of supersymmetry and the Clifford algebra story. Many, many people have been motivated by this kind of idea over the years to try and use Clifford algebras to come up with a fundamental particle theory, one that would explain the structure of the standard model. While some of these attempts have very interesting features, none of them yet seems to me to have gotten to the heart of the matter and used this kind of geometry to give a really convincing explanation of how it is related to the standard model. Some crucial idea still seems to be missing.

Last week Shamit Kachru gave a colloquium at Fermilab with the title String Theory and Cosmology. The scariest part was the beginning when he noted that what he would be talking about was work due to 500-1000 theorists and he put up a couple slides listing many of them.

He spent the first part of his talk laying out the “Landscape” story, somehow neglecting to mention that it was ugly, completely unpredictive, and told us nothing at all about the properties of the world today. He then moved on to discuss branes and cosmology, not making clear that branes explain absolutely nothing about the early universe or cosmology, although they do give you a new slogan he has come up with:

“Big bang as brane damage”

There were a couple questions at the end, with no one standing up and asking if this was a bad joke or something. I’m curious if anyone from Fermilab can explain to me what a typical experimentalist’s reaction is to this kind of talk:

1. Are they impressed by this stuff and don’t realize they’ve been fed a load of pointless nonsense for an hour?

2. Are they smart enough to realize they’ve just sat through an hour of pointless nonsense, but are too polite to say anything about this at the end of the talk?

3. Are they so smart they know in advance this will be an hour of pointless nonsense, so don’t even attend, and are off somewhere else getting real work done?