Not Even Wrong

Frank Wilczek has a new Reference Frame piece in this month’s Physics Today. It’s about the question of whether the parameters of our fundamental physical theory are uniquely determined by abstract principles, or “environmental”. He gives two reasons for suspicion about the idea that these parameters are calculable from a fundamental theory:

1. They have complicated, “messy” values and, despite much effort, no one has come up with a good idea about how to calculate them (an exception is the ratio of coupling constants in a supersymmetric GUT). He writes:

Could a beautiful, logically complete formulation of physical law yield a unique solution that appears so lopsided and arbitrary? Though not impossible, perhaps it strains credulity.

2. Some of the values are fine-tuned to make complex structures and thus life possible:

It is logically possible that parameters determined uniquely by abstract theoretical principles just happen to exhibit all the apparent fine-tunings required to produce, by a lucky coincidence, a universe containing complex condensed structures. But that, I think, really strains credulity.

Personally I don’t see the same degree of believability problems that Wilczek sees here. On the first point, it seems quite plausible to me that there are some crucial relevant ideas we have been missing, and that knowing them would allow calculation of standard model parameters, by a calculation whose results would have a complicated structure.

On the second, it’s not at all clear to me how to think about this. Sure, the fact that our universe has highly non-generic features means that it is incompatible with generic values of the parameters, but there’s no reason to expect the answer to a calculation of these parameters to be generic. I guess the argument is that there would then be two quite different ways of getting at some of these parameters: imposing the condition of existence of life, and a fundamental calculation; and if two different, independent calculations give the same result one expects them to be related. But the question is tricky: by imposing the condition of the existence of life in various forms, one is smuggling in different amounts of experimental observation. Once one does this, one has a reason for why the fundamental calculation has to come out the way it does: because it is has to reproduce experimental observations.

Wilczek avoids any mention of string theory, instead seeing inflationary cosmology and axion physics as legitmating the idea that standard model parameters are fixed by the dynamics of some scalar fields, or something similar. This dynamics may have lots of different solutions so:

We won’t be able to calculate unique values of the parameters by solving the equations, for the very good reason that the solutions don’t have unique values.

The fundamental issue with any such anthropic or environmental explanation is not that it isn’t a consistent idea that could be true, but whether or not it can be tested and thus made a legitimate part of science. It’s easy to produce all sorts of consistent models of a multiverse in which standard model parameters are determined by some kind of dynamics, but if one can’t ever have experimental access to information about this dynamics other than the resulting observed value of the parameters, why should one believe such a theory? It is in principle possible that the dynamics might come from such a simple, beautiful theory that this could compel belief, but the theories of this kind that I have seen are definitely neither simple nor beautiful. If you want me to believe in a complicated, fairly ugly theory, you need to produce convincing evidence for it, some sort of testable predictions that can be checked. Wilczek does believe that multiverse theories may provide such predictions:

Of course, the very real possibility that we can’t calculate everything in fundamental physics and cosmology doesn’t mean that we won’t be able to calculate anything beyond what the standard models already achieve. It does mean, I think, that the explanatory power of the the equations of a “theory of everything” could be much less than those words portend. To paraphrase Albert Einstein, our theory of the world must be as calculable as possible, but no more.

One can’t argue with this: if a model make distinctive predictions, and these can be compared to the real world and potentially falsify the model, one can accumulate evidence for the model that could be convincing. Unfortunately I haven’t seen any real examples of this so far. The kind of thing I would guess that Wilczek has in mind is his recent calculation with Tegmark and Aguirre that I discussed here. I remain confused about the degree to which their calculation provides any convincing evidence for the model they are discussing.

Unlike many theorists, Wilczek personally seems to be an admirably modest sort of person, and perhaps this has something to do with why the multiverse picture with its inherent thwarting of theorist’s ambitions to be able to explain everything has some appeal for him. Over the years during which particle theory has been dominated by string theory, Wilczek has shown little interest in the subject, perhaps partly due to its immodest ambitions. But I see two sorts of dangers in the way his article ignores the string theory anthropic landscape scenario which is what is driving the interest of much of the theory community in these multiverse models. As his advisor David Gross likes to point out, accepting this scenario is a way of giving up on the perhaps immodest goal he believes theorists have traditionally pursued, and one shouldn’t give up in this way unless one is really forced to. None of these models is anywhere convincing enough to force this kind of giving up.

The second danger is that what is happening now is worse than just giving up on a problem that is too hard. The string theory landscape anthropic scenario is being used to avoid acknowledging the failure of the string theory unification program, and this refusal to admit failure endangers the whole scientific enterprise in this area.

Update: It has been accurately pointed out to me that Wilczek does mention string theory briefly at one point in the article (“Superstring theory goes much further in the same direction”), and alludes to it at another place (when he talks about a “theory of everything”).

Someone wrote in to inform me that Alain Connes has made available at his web-site the full text of his long 1994 book Noncommutative Geometry. This is a rather amazing book, in many ways more of a research document than a purely expository work. All sorts of interesting things in it, mainly about Connes’s ideas linking the “geometry” of non-commutative “spaces” and the theory of operator algebras, much of this via K-theory.

Last week there was a conference on this topic at Vanderbilt. Connes gave talks there focusing on his recent work related to renormalization. Another main topic of the conference was zeta-functions, and recent developments related to Connes’s program for understanding more about them (and perhaps proving the Riemann hypothesis) using ideas from operator algebras and non-commutative geometry. The series of lectures by Consani provide a good introduction to modern ideas about zeta functions and motives that underly this program.

The CERN Council Strategy Group has produced two very interesting “Briefing Books” for its study of strategy for the future of particle physics in Europe.

For something kind of hilarious, see a paper from 2000 pointed out by one of the commenters here. It’s by Gordon Kane, Malcolm Perry and Anna Zytkow and entitled The Beginning of the End of the Anthropic Principle. The authors tell us that in string theory, “in principle, and eventually in practice, all of the masses are calculable, including the up and down quark masses, and the electron mass. There is not any room for anthropic variation of the masses in a string theory.” The opposite conclusion now seems to dominate string theory research, with the paper many people reference as launching the anthropic landscape that of Bousso-Polchinski written a few weeks after Kane et. al. (although Schellekens and no doubt others would claim that they had the idea much earlier).

David Gross recently gave a series of lectures at Princeton entitled “The Search for a Theory of Fundamental Reality” and they are available on-line. When introducing Gross, Curt Callan noted that Princeton University Press hopes that he’ll turn his lectures into a book that they would publish. The last lecture concerns the problems and prospects of string theory and is very similar to one commented on here a couple years ago in the first real posting on this weblog. Gross says about string theory “so far, we haven’t really calculated anything”, and goes on to give three reasons for this:

1. More and more possible compactifications have been found, all of which seem to be equally consistent.

2. Don’t understand how to handle broken supersymmetry.

3. The cosmological constant problem.

The reasons he gives for continued optimism about string theory unification despite these problems are that “we still don’t know what string theory really is”, and there is no consistent picture of cosmology that is understood within the string theory framework.

He explains the anthropic landscape scenario and how it destroys predictivity, then says that some of his colleagues have given up on Einstein’s dream of finding a unique theory with no adjustable parameters, but that he himself won’t do so until he is forced to, and he isn’t forced to yet since we don’t know what string theory is. He made his usual speculation about string theory leading to some still unknown new emergent view of space and maybe time, then went on to give three reasons for supporting continued research in the subject despite its failure to make any progress on its main problems:

1. String theory has given new insights into gauge theory and maybe it will help solve QCD.

2. String theory has given new insights into mathematics.

3. String theory has lead to new speculative phenomenological scenarios (braneworlds).

About point 3. he describes the possibility of evidence for such scenarios showing up at the LHC as “very unlikely” and even says that he is willing to take bets with anyone for any amount of money that the LHC will not see such things (perhaps he should have discussed this with the authors of the recent report that used these scenarios to try and sell the ILC…). I’ve seen this phenomenon before, but it seems to me peculiar to give as a positive argument for string theory that it leads to the study of phenomenological scenarios that you don’t believe.

After his talk, a questioner asked him if string theory might turn out to just be unsuccessful (i.e. wrong), to which Gross responded “String theory can’t be wrong (or even killed)”. He elaborated by saying that it couldn’t be wrong because it was related via AdS/CFT to N=4 supersymmetric Yang-Mills, which was in turn was related to the standard model. Somehow he felt this was an argument that string theory couldn’t be wrong, only incomplete. He acknowledged that recently he had come to the point of view that string theory was not something that led to unique predictions about the world, but that it is incomplete. In this view, string theory is just a framework, like QFT, and some new ideas need to be added to it to turn it into something that really relates to the real world.

Someone asked him about LQG, and he responded by saying that he doesn’t usually comment on LQG in a polite audience, that it wasn’t very successful, didn’t connect to GR, and was not of any interest to physics.

He ended with some pessimistic comments about the possibility that the scientific community might lose the will to go on at some point in the future as it became more and more difficult to get information about shorter and shorter distance scales, or moments closer and closer to the big bang.

Update: There’s an article entitled Hard Landscape by J.R. Minkel in the June 2006 Scientific American. It deals with the Denef-Douglas work showing that finding a vacuum in the landscape with sufficiently small CC is likely to be a computationally intractable NP hard problem.

“The Douglas-Denef paper is surely a problem for drawing conclusions about what the landscape predicts,” asserts Thomas Banks of U.C. Santa Cruz.

Update: Besides the well-known Theoretical Particle Physics Jobs Rumor Mill which deals with tenure-track hiring, there’s now the Theoretical Particle Physics Postdoc Jobs Rumor Mill, which deals with postdocs. This year I count among the postdoc hires 31 string theorists, 12 phenomenologists and 5 hard to characterize, with several major institutions that hire multiple post-docs still only hiring string theorists. The rumors I’ve been hearing that only phenomenologists are getting jobs seem to be complete bunk.

Update: heppostdoc points out that the Postdoc Jobs Rumor Mill is very new and the data is incomplete. Probably complete data would show postdoc hires not as heavily weighted towards string theory.

Update: There’s a conference going on near Washington this week entitled From Quantum to Cosmos: Fundamental Physics Research in Space. Mark Trodden is blogging from the conference over at Cosmic Variance.

Update: Eric Weinstein, who continues to conduct his research in mathematics and physics from within the financial industry here in New York, will be giving a talk at the Perimeter Institute on Wednesday at 2pm, with the title “Gauge Theory of Economics”. Here’s his abstract:

The close relationship between geometry and fundamental physics can be seen from surveying the basic equations underlying the known forces of nature. What has made these repeated appearances of gauge fields and curvature tensors particularly striking in recent years is lack of any comparable applications outside of the Standard Model and General Relativity. In this talk we will pose the question of whether Yang-Mills theory is simply a unifying principle with application well beyond its current use by exhibiting unreasonably effective applications of Gauge Theory beyond those familiar in the Natural Sciences. Armed with these examples, we will then revisit the question about what is most truly special about the Standard Model and Relativity.

Over the last week or so I’ve heard privately from several very different parties with complaints about the comment section here. The general feeling is that it would be more useful and attract more serious contributions if the level of uncivil, disrespectful ad hominem attacks was much lower. One contributing factor mentioned is that anonymity allows people to behave in uncivil behavior that they would not engage in if their names were publicly attached to their words. On the other hand, the worst offender in this is someone who is not anonymous.

I’d be curious to hear thoughtful comments by others about this. My own feeling at the moment is that the criticism is accurate: the uncivil atmosphere here keeps many serious people who would have something interesting to contribute from doing so. The anonymity is probably part of this problem, although given the current unhealthy situation in particle theory, some people have very legitimate reasons for keeping their comments anonymous.

In many ways I think the comment section has been a success, but it could stand a lot of improvement. Unfortunately I don’t know of any really successful models out there to follow. Among the more active blogs by physicists, Cosmic Variance does a good job of keeping a civil discussion going, but it is rarely about physics these days. Jacques Distler’s Musings has high-level content in its postings, but no one has submitted a single comment about physics there in over a month and a half. The comments at Lubos Motl’s Reference Frame are as uneven as the blog’s proprietor.

I already delete quite a few comments on grounds of lack of civility, but tentatively plan on trying to raise that standard by deleting a larger fraction of uncivil comments, especially if they are posted anonymously. It would help if people could keep the following in mind when posting comments:

1. Please consider abandoning anonymity and posting under your real name, unless you have a good reason for not doing so.

2. Please take much greater care to keep comments civil and respectful. Ad hominem argument about the ignorance and lack of intelligence of people you disagree with has no place here.

3. Please ignore silly comments when they appear. Maybe I’ll also think they are silly and just adding to the noise and will get around to deleting them, maybe not. But in any case you’re not adding anything by submitting a comment criticizing the silliness, but instead are adding to the hostility level.

Constructive comments are welcomed. One thing to keep in mind is that I already am spending more time on this than I should, suggestions that involve a lot more work on my part are non-starters.

The string theory anthropic landscape point of view has now become so widely accepted and entrenched in the particle theory community that various people are making their claims about having had the idea first. The standard first paper that people generally reference is Leonard Susskind’s February 2003 The Anthropic landscape of string theory, which now has 243 citations. Susskind claims credit at least for the “Landscape” terminology in his recent book.

Last month Dutch string theorist Bert Schellekens posted a paper on the arXiv entitled The Landscape “avant la lettre”, in which he claims credit to some extent for the idea. He is quite enthusiastic about the Landscape as a paradigm shift and a new way of doing physics:

… I think even today we are only in an intermediate stage of a very slow shift of opinions regarding the objectives of our field. Although landscape ideas and even the anthropic principle are now at least discussed, it seems to me that the importance of the landscape is still severely underrated. I have tried to express my enthusiasm about the recent progress during seminars, but apparently with little success.

Schellekens claims that:

My own thoughts in this direction started around 1987. The year before I had published a paper with Wolfgang Lerche and Dieter Lust. Like other authors at the time, we found large numbers of four-dimensional chiral string theories, but much more than others we made a point of strongly emphasizing the non-uniqueness of the result.

He goes on to say that already back then it was clear to him that string theory was sending the message “if we find one vacuum we are going to find a huge number of them.” He recalls that when he was working at CERN in the years before 1992 he was promoting the anthropic string theory landscape idea and encountering a lot of resistance, often from people who now tell him that they had always been saying this kind of thing.

In 1998, at the occasion of his inauguration at the University of Nijmegen he gave a speech on this subject in Dutch. In the arXiv preprint Schellekens reproduces the Dutch text of his speech, together with an English translation. He notes that he used the Dutch word “landschap” in the text, although he mostly referred to the landscape using the Dutch word for a “mountain range”.

Schellekens admits that string theory may not be correct, but he says that string theory implies the landscape, so for string theory to be correct the landscape must exist. His only comment indicating that this might be a problem for string theory is that

…the unexpectedly huge size of the landscape is making it a lot harder to convince ourselves of that.[e.g. the correctness of string theory]

He does admit that back in 1998 he expected the size of the landscape to be much smaller than it now appears to be, smaller than the 10⁸⁰ vacua that, uniformly distributed, could cover all possible values of the standard model parameters to the accuracy that we can measure them. So he expected that one would be able to somehow check string theory by seeing if one of the vacua agreed with the real world. Now that the number of vacua seems to be vastly greater than this, eliminating any reasonable hope of checking string theory this way, for some unfathomable reason his enthusiasm for the idea is undiminished if not intensified.

If you just can’t get enough of landscape discussion, there are recent blog entries on the topic by Sabine Hossenfelder and Alejandro Satz.

Update: The last-gasp hope for getting a prediction out of the landscape is that there is some useful structure in the landscape, so that it doesn’t densely cover all possible standard model parameters. Washington Taylor and Michael Douglas have been looking for such a thing amongst vacua, trying to find some correlations between properties of these vacua. For more about this, see Taylor’s web-page. Lubos has a blog posting about all this, in which Taylor explains the philosophy:

If we find 5 models with features X and Y of the standard model which all have feature Z which is not yet observed it is not very definitive. If we look in different parts of the string theory landscape and find that all 10²⁰ models we know how to construct with features X and Y of the standard model have feature Z also it begins to carry some weight as a possible prediction.

So far, as you might expect, since there is no known reason for such correlations, they haven’t found any. Lubos reports:

Wati’s result in his particular examples was that there was virtually no information in the correlations: the difference was one bit and the distributions of different quantities were essentially independent Gaussians.

and goes on to rant:

Surely the physicists have not been working for 30 years to extract 1 bit of information – whose probability of being correct is moreover 50 percent. Even if there were any correlation, I would probably find such a correlation physically uninteresting. We know for sure that some of these correlations would agree with those observed in the real world, and some of them would not.

What will you do with this probable outcome? Will you overhype the “successful” patterns as evidence that the landscape reasoning is good, while you will be silent about the “unsuccessful” ones? I would count this activity as a part of astrology or catastrophic global warming theory, not physics. It’s frustrating to see that this is what is apparently being intended.

I wonder whether the people who were producing the very convoluted microscopic theories of the luminiferous aether in the 19th century really believed that this was the way to say anything new about physics – or whether most of them did these things just to do something and keep their jobs. Einstein took over in 1905 and showed not only that the aether was a ludicrous fantasy – but moreover, the absence of the aether is one of the basic principles that underlies his relativistic revolution in physics. Today, all of us – except for those in loop quantum gravity – know that the aether is a silliness that is not realized physically and that was never well motivated.

My feeling about the random model building and random model guessing is somewhat analogous to the random construction of the aether from gears and wheels. We’re missing something and we should not fool ourselves into thinking that we’re not.

Update: The Harvard physics department seems to be having quite a few seminars on the Landscape, and one participant reports:

A funny aspect of these discussions is that one can’t quite distinguish which of the considerations are jokes and which of them are meant seriously. At least I can’t distinguish them.

Some rather strange things are going on at the arXiv, especially in the hep-th section:

Besides the usual string theory papers, which just get more and more pointless as time goes on, some very weird things have started to appear on hep-th. Last night, there was a new paper entitled Amplitude for existence of spacetime points that makes no sense to me. It’s by Monica Dance, who seems to have no academic affiliation, but does have a Hotmail account. Not clear why the hep-th moderator allows this kind of thing. One explanation would be that earlier this year she put Symmetry limitations on quantum mechanical observers, and conjectured link with string theory on hep-th, an equally nonsensical document which presumably was all right because it had “string theory” in the title. Maybe once you get one paper about “string theory” on hep-th, you become an “active researcher” and can put whatever you want there.

Actually, to get to be an “active researcher” according to the arXiv, as long as you’re studying string theory, you don’t need to even ever have written a paper at all. Recall that arXiv trackbacks to this blog have been banned on the grounds that I’m not an “active researcher” (for more about this, go here). But this hep-th paper has a trackback to this blog entry by Nicola Ambrosetti. Ambrosetti’s blog contains some fine entries and having trackbacks to it makes good sense, but he appears to be a student at Neuchatel who has never written a paper, so I would have guessed that according to arXiv standards he wasn’t yet an “active researcher”. Maybe standards are different when your blog entries have titles like Barton Zwiebach Rules!.

Over the last few months I’ve written quite a few blog postings that discuss arXiv papers. In many cases I happen to think that either the posting or the discussion in the comment section is something that someone interested in the paper might find worthwhile. In the case of postings about string theory papers (here and here), non-string theory papers, and non-string theory papers claiming to be string theory papers, no trackbacks to my blog were allowed. This is what I expected, but for some mysterious reason, a trackback to this blog entry about a paper critical of string theory was allowed. So, it seems that the arXiv is allowing trackbacks to my blog entries only when they are about papers criticizing string theory.

None of this makes any sense to me, so I tried politely writing to the arXiv person at Cornell that my logs showed had examined my blog entry just before their trackback system generated a trackback to it, asking about what was going on. No response to that inquiry, as to all my other inquiries about arXiv trackback policy. To find out what their policy now is, I guess I’ll just have to wait for the relevant authorities to get around to posting a blog entry or writing a comment at some blog somewhere, since that seems to be their preferred manner of dealing with this issue.

Update: I did get an e-mail response from someone at Cornell about my enquiry about trackbacks. It didn’t address the question of how hep-th trackbacks are now being moderated, but did point out that the trackback system is still in an experimental state, that they have recently had significant personnel changes, and that sorting out the trackback system hasn’t been one of their highest priorities.

Update: Lubos is even more out there than usual with his comments on this. It seems that my objections to the Dance paper are an example of sexism.

If you just can’t get enough of pictures of mathematicians, head over to the Oberwolfach Photo Collection. This is a huge collection, which I recently ran across when trying to locate something by Graeme Segal. It also includes a photo of a frequent contributor here.

The AMS has put quite a few whole books on-line. Recently they added the three-volume set A Century of Mathematics in America here, here, and here. Another interesting volume is Mathematics into the Twenty-First Century, which includes some wonderful survey articles, including a very long series on Lie theory by Roger Howe, and one on Geometry and Quantum Field Theory by Witten.

Terrance Tao has a sort of research blog.

In the category of interesting-looking work that I haven’t yet had time to read carefully and think about, here are two papers on an approach to studying pure Yang-Mills theory, by Freidel and Freidel and collaborators.

Update: A correspondent suggests I mention another famous mathematician whose photo is on the Oberwolfach site.

HEPAP today released a new publication designed to convey to the general public excitement about prospects for particle physics in the coming years. It’s entitled Discovering the Quantum Universe, and it has a companion web-site. Both the web-site and the document itself are beautiful and impressive productions. The web-site also contains the earlier 2004 HEPAP report Quantum Universe, which was mentioned in one of the earliest posts of this blog. The newer document is based on an earlier version from last summer, and one of its main goals is to make the case for a linear collider. In some sense this is promotional material for the conclusions recently reached by the EPP2010 panel. Also part of the promotional activity today is a briefing for members of Congress that will include a talk by my colleague Brian Greene.

While I hope that this all has the intended effect of getting the public, the Congress and the Administration excited about particle physics and willing to support it at the level necessary to fund a new generation of machines and experiments, as you might guess I have my doubts about the wisdom of some of the material included in this report. Unlike the EPP2010 report, which oversold string theory a bit, this report oversells it a lot, with language like:

… preliminary studies have looked at the ability of linear collider experiments to detect the telltale harmonies of strings. Here linear collider precision is essential, since the string effects appear as small differences in the extrapolated values of the superpartner parameters. A combined analysis of simulated LHC and ILC data shows it may be possible to match the fundamental parameters of the underlying string vibrations.

The inclusion of this kind of language seems to me to be misleading and irresponsible. Ten years from now when we have real LHC data, know that the ILC can’t tell us anything about string theory, and are asking the US government to put up large sums to finish the ILC, we’ll have to hope that the relevant decision makers didn’t get convinced by this report that the ILC is a machine designed to get information about string theory.

Update: More about this at Cocktail Party Physics.

The Dibner Institute and Burndy Library at MIT will soon be closing, with the Burndy collection moving to the Huntington Library in California near Caltech. The Dibner Institute is devoted to research in the history of science and technology, and I mentioned it a couple years ago here. Among the interesting things the Dibner has on-line are copies of lecture notes on quantum electrodynamics from Freeman Dyson in 1951 and Fritz Rohrlich in 1953.

Stony Brook announced yesterday that Jim Simons will be making a $25 million dollar donation to the university, focused in the area of mathematics and physics. This is a great deal of money for a math or physics department, and it is the largest single cash donation ever made to any of the SUNY institutions.

Simons was responsible for building up the Stony Brook math department, which he joined as chair in 1968. About his hopes for what his donation will do, he says:

During the past thirty years mathematics and physics have grown increasingly intertwined. This is particularly true in the cases of string theory, quantum field theory and cosmology, which have all depended upon and stimulated advanced work in geometry and topology. Buttressed by its close relationship with Brookhaven National Laboratory and building on a fine faculty already in place we believe our gift can help propel Stony Brook into the very top rank in these central fields.