Video of the panel discussion at Toronto is now available, so one can hear some of the context of the comments that were reported in the recent New York Times article. As reported, the audience voted 4 or 5 to 1 against the anthropic principle. Unfortunately the camera was not on the panel during the vote, so one can’t tell from this video how the panelists voted.
Some other things that weren’t reported: while Andy Strominger commented that he saw no reason for pessimism, he also said he thought the odds were against any data relevant to quantum gravity or string theory coming out of the LHC. Steve Shenker said that he was very much bothered by the fact that it was starting to look as if one could associate some sort of “quantum gravity” dual to any quantum mechanical system whatsoever, so any notion of uniqueness was completely gone.
There were several skeptical questions from the audience. Someone with a Russian accent pointed out that it was becoming increasingly difficult to argue the case for string theory in the physics community, and asked what argument he should use in its favor. The panel didn’t seem to want to address this, but Shenker finally said “Only consistent theory of quantum gravity”. The next question wasn’t really audible, but had something to do with “it’s been 20 years”. Shenker’s response was something like “most of us don’t want to think about this, we haven’t done as well as in other 20 year periods”. Later on someone asked “Can you imagine any experiment in the next 20 years that will falsify string theory”, getting no real response except “You’re not supposed to be asking that” from Shenker. Another question from the floor was about why none of the panelists had mentioned M-theory, which didn’t get much of an answer except from Nathan Berkovits who commented that in particle theory problems not solved in five years stop being discussed.
In their speculation about the future, many of the panelists invoked the possibility of having to change quantum mechanics. From the floor Witten speculated that quantum mechanics was only valid in asymptotic regions of space time, with something different needed to understand the interior. Also from the floor Susskind speculated that the splittings into different universes of the many-worlds interpretation of quantum mechanics were the same as the cosmological bubbling off of different baby universes. Several panelists responded that they had no idea what he was talking about.
The emphasis on vague ideas about the foundations and interpretation of quantum mechanics led Martin Rocek to point out that there was one field of study in physics that had gone nowhere in the last eighty years: the study of the interpretational issues in quantum mechanics. Lee Smolin rose to the defense of this field, claiming that it had led to recent ideas about quantum computers.
Also now available online are videos of the public talks by Dijkgraaf and Susskind. Susskind tells the audience that there is a “War” or “battle of intellects” going on between two groups of physicists, which he describes as being “like a high-school cafeteria food fight”. The two groups are the “As” (A for anthropic), and the “Es” (E for elegant). He describes the belief by the Es in mathematical elegance as “faith-based science”, and says that they are in “psychological denial” about the existence of the landscape, then goes on to give the standard arguments for the landscape and the anthropic use of it to “explain” the value of the cosmological constant. He refers to belief in the existence of a vacuum selection principle as analogous to belief in the Loch Ness monster. He ended his talk by claiming that the As were winning the war, with the Es in retreat.
Dijkgraaf’s talk was completely standard string evangelism, and except for a couple slides mentioning D-branes and black holes, could easily have been given, completely unchanged, twenty years ago.
