I was dubious of the value of a new “sci.physics.strings” newsgroup when it was first proposed, but now must admit it seems to have been a great idea It started up a week or two ago, and quickly someone asked the seemingly innocuous question of how many different possible vacuum states were expected in string theory. This is a hugely controversial issue among string theorists, largely because recent evidence is that the number is definitely astronomically large, and this makes it very unlikely that current ideas about string theory can ever be used to predict anything about the real world.
A lot of the discussion revolves around the “KKLT” proposal for constructing a large number of these vacuum states. The acronym is the initials of the authors, three of whom are at Stanford: Shamit Kachru, Renata Kallosh and Andrei Linde. Also at Stanford is Lenny Susskind, who has been spending the last year or so going around giving talks on the “Landscape of String Theory”. It’s hard to believe this, but Susskind’s claim is essentially that the lack of predictivity of string theory is a good thing, since it allows so many possibilities that anything can happen. One can then invoke the “Anthropic Principle” to explain why the world is the way it is. It seems that Susskind is even writing a book about this wonderful “discovery”.
Amazingly enough, the thread about this on sci.physics.strings, entitled “Conceptual question”, has brought a public attack on the “Stanford propaganda machine” by a well-known European string theorist (Wolfgang Lerche), a detailed defense of his ideas by one of the KKLT authors (Kachru), contributions from the inimitable Lubos Motl from Harvard, and, while I was writing this, a defense of the anthropic principle from Joe Polchinski just appeared, which attacks the “cult of monovacuism” embodied by David Gross and Ed Witten.
Thanks are due to the creators of this newsgroup. Pass the popcorn!