Video of David Gross’s talk at the Physics at the LHC 2010 conference is now available. He devotes much of the talk to reviewing predictions he made back in 1993 of what would happen by 2008, and making new predictions for what will happen by 2020.
The 1993 experimental predictions that didn’t work out could mostly be explained away by the SSC cancellation, which pushed investigation of TeV scale physics into the future at the LHC. In 1993 Gross predicted two light Higgs particle and superpartners (due to supersymmetry), new Z-mesons (i.e some new U(1) gauge fields) and “There will be cloudy evidence of superstrings.” His 1993 predictions about theoretical developments related to string theory didn’t work out very well:
String field theory will begin to be a useful tool and will illuminate the underlying symmetries of the theory. (not at all, he admits)
New mechanisms of string supersymmetry breaking will be discovered leading to new and definitive low energy models. (new maybe, certainly nothing definitive)
The conceptual revolution arising from the nonperturbative formulation of string theory will be in full swing, revolutionizing the concepts of space-time geometry. (“on its way, but it hasn’t really revolutionized our concepts“)
For 2020, Gross makes one striking non-scientific prediction: The US will join CERN and there will be a joint plan to build a linear collider at CERN.
His experimental predictions include a repeat of the 1993 ones (superpartners, new Z-mesons, and the Higgs, although now he only mentions one Higgs), except that he has now given up on even “cloudy” evidence of superstrings showing up at the TeV scale. His theoretical predictions include a much scaled back version of the 1993 theoretical predictions about string theory: “If we’re lucky, string theory will start to be a theory with predictions (right now we don’t understand it)”.
As far as supersymmetry goes, he says that he is “totally convinced that SUSY should be there, at the 50% level” and repeats his offer to take bets at 50/50 odds. One of the main motivations for this is the argument that SUSY can provide a suitable dark matter candidate, and he predicts observation of dark matter by 2020 at non-accelerator experiments.
Finally, he ends up with an attack on the anthropic explanation of the CC, and predicts that a better one will be found by 2020.
Update: See Lubos, who has a lot more energy than I do, for a transcription of Gross’s predictions.