There’s almost too much to keep track of the last couple days on the string theory controversy front:
Burton Richter of SLAC has a Reference Frame piece in the latest Physics Today entitled Theory in particle physics: Theological speculation versus practical knowledge. Richter shares my point of view that the Landscape studies currently popular in string theory are not science:
To me, some of what passes for the most advanced theory in particle physics these days is not really science. When I found myself on a panel recently with three distinguished theorists, I could not resist the opportunity to discuss what I see as major problems in the philosophy behind theory, which seems to have gone off into a kind of metaphysical wonderland. Simply put, much of what currently passes as the most advanced theory looks to be more theological speculation, the development of models with no testable consequences, than it is the development of practical knowledge, the development of models with testable and falsifiable consequences (Karl Popper’s definition of science)…
The anthropic principle is an observation, not an explanation… I have a very hard time accepting the fact that some of our distinguished theorists do not understand the difference between observation and explanation, but it seems to be so…
What we have is a large number of very good people trying to make something more than philosophy out of string theory. Some, perhaps most, of the attempts do not contribute even if they are formally correct.
The issue of Nature that just came out today has an article about the controversy by Geoff Brumfiel with the title Theorists snap over string pieces: Books spark war of words in physics. He describes Lubos Motl’s reviews of the Smolin book and mine on the Amazon web-site, and quotes Polchinski and Susskind. The reaction of string theorists to the books is said to be:
Few in the community are, at least publicly, as vitriolic as Motl. But many are angry and struggling to deal with the criticism. “Most of my friends are quietly upset,” says Leonard Susskind, a string theorist at Stanford University in California.
The books leave string theorists such as Susskind wondering how to approach such strong public criticism. “I don’t know if the right thing is to worry about the public image or keep quiet,” he says. He fears the argument may “fuel the discrediting of scientific expertise”.
Susskind will be giving a public lecture October 17 at UC Davis on String Theory, Physics and the “Megaverse”.
Polchinski avoids the problems associated with the failure of string theory as a unified theory, and promotes in a somewhat overhyped way the idea that string theory explains the RHIC data.
Finally, Smolin makes an offer to string theorists that I feel I should try and match, hoping they will read his book to better understand exactly what he has to say:
If they don’t want to buy it, tell them to get in touch with me and I’ll send them a copy.
One thing Brumfiel gets a bit wrong is that my problem with string theory is not quite what he says “a fear that the field is becoming too abstract and is focusing on aesthetics rather than reality.” The problems I see are rather different, with mathematical abstraction one of the few tools still available to theorists trying to make progress.
The same issue of nature contains an editorial Power and Particles lustily repeating much of the standard hype about string theory, noting that there are problems, but ending with:
Critical-mindedness is integral to all scientific endeavour, but the pursuit of string power deserves undaunted encouragement.
The editorialist definitely does not seem to be of the opinion that alternatives also deserve to be encouraged.
Finally, lots of reviews of Lee Smolin’s book:
Unburdened by proof by George Ellis, also in Nature. Ellis takes the opposite point of view from the Nature editorialist, calling for more research on alternatives to string theory.
A loopy view by Michael Duff, in Nature Physics. Duff is extremely hostile to Smolin’s book, sneering at Smolin and claiming that his book will “leave the reader rooting for strings” (funny, but this doesn’t seem to have been its effect on most reviewers…). Duff agrees that there are problems with string theory, but claims that the problems Smolin correctly identifies are exactly the ones that he himself first identified back in 1987. String theorists like Duff seem torn between claiming that criticisms of string theory are crackpot nonsense, and that they themselves made them first. He goes on to furiously attack various straw men, accusing Smolin of “denying that any progress has been made!” (something I don’t think Smolin does at all), and answering the criticism that string theory makes no predictions despite more than twenty years of effort by discussing how theories that did make predictions have sometimes taken a long time to be confirmed (or remain unconfirmed).
The string theorists were scammed! by Peter Shor on Amazon.
The Trouble With Physics by Sean Carroll at Cosmic Variance. If I can find the time, I may write about some of my problems with this review as a comment over there.