So, I'm back from the first day at the conference and have to say I'm very fortunate for my first ever conference to be so huge. I was also lucky to have a postdoc from my department sat next to me, who pointed out all the 'famous' people to me! I'll give a brief summary, although I won't even attempt to write detailed notes here on the talks!
The opening talk of the conference was given by Alan Guth. I have to say he was a good choice, not only since he's one of the fathers of inflation, but he's also a really good speaker. He began with a brief description of the conference that took place 25 years ago. He dug out the schedule, and his handwritten notes from that conference; pointing out that in the first week of the last conference there were 10 talks, compared to 11 in the first day this year, which he attributed to inflation (the first of many "jokes" about inflation!) The notes he said he will make available at this URL, http://ctp.lns.mit.edu/~guth/VEUmemories.html , presumably sometime next week. Then he spoke about the successes of inflation, and also explained the answer to a question I asked spacetiger for references for the other day; namely that of eternal inflation. The "bottom line" of his talk was that we have never had a model of the universe that both works so well, but is also so mysterious.
The second speaker was another of the greats (I'm sure I'm going to use that phrase a lot in this summary!); namely Alexei Starobinsky. His talk was mainly on stochastic inflation. He spoke well for the first part, but then was rushed towards the end: it's a bit of a shame really, since I could have sat and listened to him for hours! He stressed the need for new observational evidence, and said that going back to the history of the universe is possible, but we require new measurements of some new "light scalars."
Next was Demos Kazanas. He spoke about cosmological inflation from a personal perspective, detailing his career in the field. Then we had morning coffee break (which I welcomed, since I'm not used to these early mornings!)
The first speaker after the break was Stephen Hawking, answering the question 'why did the universe inflate.' His talk was mainly on the no boundary condition and a semiclassical approximation to the wavefunction of the universe. I have to say that listening, and seeing Prof Hawking give a seminar made me in awe of him. He answered a question at the end of his talk, which took him a while to "type" out into the voice synthesiser, and it just hit me that this guy does everything in his head. If he did have the physical capabilities of the rest of us, then he'd be an extraordinary scientist, but to be able to do what he does without writing anything down, or even being able to quickly converse with people is utterly amazing. He is clearly devoted to science, because seeing the amount of effort it takes him to talk shows that it would have been a lot easier for him to give up years ago. Anyway, he concluded that 'volume weighting gives a high probability of a large amount of inflation.
Next up was Andrei Linde who spoke about the general inflationary paradigm, models of inflation (inflaton+curvaton) and alternative models (ekpyrotic/cyclic scenario). He concluded that string theory can describe inflation in the early universe as well as inflation now; and that eternal inflation and string theory have joined each other in the landscape.
After lunch, Katsuhiko Sato spoke about supernovae data, and multiproduction of universes. He commented on three papers that he had published before Guth, and then discussed how 'mushroom' wormholes start a multiproduction of universes. After him Paul Steinhardt discussed inflationary and cyclic models of the universe. He pointed out some problem with inflation (unpredictability, persistence of memory, geodesic incompleteness, entropy problem), and then sought a model that didn't have these problems; namely the cyclic or ekpyrotic model. He ended by pointing out observational predictions of the model regarding gravitational waves and non-gaussianity.
Slava Mukhanov gave the next talk, on cosmological perturbations: theory vs observations. He discussed the need to amplify the quantum fluctuations in an expanding universe, and discussed how they transfer from the Planckian scale to the galactic scale through Hubble expansion.
The talk immediately after tea was by Jim Bardeen, entitled 'Backreaction as an explanation for DE?' Now, I've read a few of his papers, and have to say that I found them pretty tough, so expected his talk to be difficult to understand. It didn't turn out to be too bad; he discussed gauge choices and gauge invariant quantities. He then mentioned some of the recent backreaction papers like those by Wiltshire and Kolb et al. He then spoke of the counter arguments to these, from Wald, Flanagan. To conclude he said that 'Newtonian gravity is a good description in the presence of large perturbations, and that there is no significant backreaction.'
Next up was Henry Tye, talking about "brane inflation: an update." I found this talk very interesting. He started by discussing how inflation exhibits itself in the string environment, then went on to discuss in more detail one of these ways; namely brane inflation. He mentioned brane antibrane scenarios, and the annihilation of the branes ending inflation. Then, he spoke about possible non-gaussianity from two models of inflation: multifield inflation and DBI (Dirac-Born-Infeld) inflation. Finally, he mentioned how one may use the gauge theory/gravity duality in order to 'measure' the warp geometry of the throat in the bulk.
The final talk was by Ian Moss, who was meant to talk about the Hartle-Hawking state but, since both authors were talking about this, changed his talk to "Thermal Fluctuations. " Basically, this entailed looking at thermal fluctuations instead of density fluctuations. HE outlined a theory (which I'll skip over) and concluded that the there is a way to determine this model from multi-scalar field theories.
And, that was the end of the first day. I have to say I'm pretty tired, but had a brilliant day. And, looking at the schedule for tomorrow, it looks like more of the same high quality!
