General Relativity & Quantum Cosmology

Philosophy of physics, puzzles about the content and status of foundational principles – the logic of physicists’ basic assumptions, especially with regards to space and time, and the history of science, e.g. exactly how Einstein made his discoveries.

Quantum gravity, quantum processes in the early universe, evaporation of black holes, limits on the measurements made by real detectors (coupled to the environment), and with regards to mathematical problems, studying techniques rather than finding solutions.

I comment on rather significant recent developments that are relevant for proposals I had presented in previous PI seminars. The Fermi/GLAST space telescope has reported observations that would naturally fit previous formalizations of Planck-scale-induced in-vacuo dispersion (but also quite a few other things). And the unexplained excess noise found at the GEO600 interferometer is just of the type that had been previously described in terms of phenomenological models of spacetime foam (but may well be caused by quite a few other things). On the pure-theory side I can finally keep my promise to show that spacetime noncommutativity is a valuable tool of exploration of nonclassicality of spacetime, allowing the derivation of discretized spectra of distance, area, volume, and also providing a completely new overall geometric picture, in which amusingly the number Pi looses some of its privileges.