Well, my work at the Quantum Gravity school over (see previous posts here, here and here), I hopped on a plane yesterday, in order to return to Los Angeles. It was an excellent time. I enjoyed being in Mexico again, and seeing a new part of it (see posts to come), and the school was well organized and very enjoyable. The students were very receptive overall, and I spent a huge amount of time chatting with them about physics between sessions, over lunch, and on the bus back and forth between the campus and the city (and on the excursion on Sunday for a while). A number of students seemed very interested in some of the quantum gravity phenomena that are possible to describe using string theory – surprised in most cases (since the background independence issue that keeps being waved about by some as a naive (in my view) and bluntly used principle seems to have served as a block to many) – and it was a pleasure to be able to open them up to new physical ideas. It worked pretty well because I gave them three lectures on the basics of string theory, and so could build on that material in the one to one discussions to explain more detail.
Dynamical changes of spacetime dimension is one thing that captured a lot of interest, as well as string theory’s various ways of showing in model examples how spacetime is an emergent, classical approximation to an underlying quantum description that does not have manifest spacetime geometry. The latter is something that all approaches to quantum gravity hope to realize in one way or another (since those sorts of ideas and fantasies about what quantum gravity should be appeared in the mid 20th Century), and exactly how it emerges in string theory is a beautiful story. Who knows, perhaps they will take these hints from string theory about how quantum gravity can work and develop them [...] Click to continue reading this post