The String Vacuum Project, described as “a large, multi-institution, interdisciplinary collaboration”, that has been established over the last few years, is having its Kick-Off Meeting next month at the University of Arizona. This group had submitted grant proposals to the NSF for funding of such a project in the past, but I don’t know if they ever managed to get NSF or other funding. They motivate the project by claiming that
Given that relatively large numbers of string vacua exist, it is imperative that string phenomenologists confront this issue head-on…
In this context “relatively large” involves numbers like 10500, 101500, etc.
Bert Schellekens has a web-site devoted to promoting the Anthropic Landscape, where he argues that
The String Theory Landscape is one of the most important and least appreciated discoveries of the last decades.
Besides the web-site, he has slides from two general talks on-line (here and here). In the talks he compares string theorists to the famous Emperor parading in no clothes, except what he is criticizing is those string theorists who have been unwilling to acknowledge the existence and importance of the anthropic landscape. He’s critical in particular of
those people claiming that they have always known that String Theory would never predict the standard model uniquely, but that they did not think this point was worth mentioning.
His modernized version of the fable of the Emperor goes as follows:
Many years ago, there lived some physicists who cared much about the uniqueness of their theories. One day they heard from two swindlers that they could make the finest theory which was absolutely unique. This uniqueness, they said, also had the special capability that it was invisible to anyone who was stupid enough to accept anthropic thinking.
Of course, all the townspeople wildly praised the magnificent unique theory, afraid to admit that anthropic thoughts were inevitable, until Lenny Susskind shouted:
“String theory has an anthropic landscape”
It’s not clear who he would identify as the “two swindlers”….
According to Schellekens, the “string vacuum revolution” is on a par with the other string theory revolutions, but most people prefer to overlook it, since it has been a “slow revolution”, taking from 1986-2006. The earliest indications he finds is in Andy Strominger’s 1986 paper “Calabi-Yau manifolds with Torsion”, where he writes:
All predictive power seems to have been lost.
and in one of his own papers from 1986 where the existence of 101500 different compactifications is pointed out.
Schellekens claims that “string theory has never looked better”, but he completely ignores the main question here, the one identified by Strominger in 1986 right at the beginning. If all predictive power is lost, your theory is worthless and no longer science. What anthropic landscape proponents like him need to do is to show that Strominger was wrong; that while string theory seems to have lost all predictive power, this is a mistake and there really is some way to calculate something that will give a solid, testable prediction of the theory. The String Vacuum Project is an attempt to do this, but there is no evidence beyond wishful thinking that it can lead to a real prediction. Schellekens has worked on producing lots of vacua and describing them in a “String Vacuum Markup Language”, and in his slides describes one construction that involves 45761187347637742772 possibilities. These possibilities can be analyzed to see if they contain the SM gauge groups and known particle representations, but this is a small number of discrete constraints and there is no problem to satisfy them. The problem is that one typically gets lots and lots of other stuff, and while one would like to use this to predict beyond-the-SM phenomena, there is no way to do this due to the astronomically large number of possibilities.
He lists goals for the future (“Explore unknown regions of the landscape”, “Establish the likelihood of SM features”, “Convince ourselves that the standard model is a plausible vacuum”), but none of these constitutes anything like a conventional scientific prediction that would allow one to test to see if what one is doing has any relation to reality. In the end, he comes up with the only real argument for the String Vacuum Project and other landscape research, that of wishful thinking:
… and maybe we get lucky.
Update: There’s a story about the String Vacuum Project in this week’s Nature by Geoff Brumfiel. It includes skeptical comments from Seiberg and yours truly, as well as Gordon Kane’s claim that:
evidence supporting string theory could emerge “within a few weeks” of the [LHC]’s start-up.
Update: At the blog Evolving Thoughts, there’s a discussion of whether theoretical physicists have now taken up a “stamp-collecting” model of how to do science. I point out that this is stamp-collecting done by people who don’t have any stamps, just some very speculative ideas about what stamps might look like.