In the definition of a differential manifold in General Relativity (GR) the Hausdorff condition is typically assumed. In my talk I will investigate the consequences of dropping this condition. I will argue that there are good reasons to regard non-Hausdorff manifolds as basic objects of GR, together with Hausdorff manifolds. However, it is not clear whether they can be regarded as physically reasonable basic objects of GR. I will argue that some of the objections to their physical reasonability can be refuted if we understand them as representing a bundle of alternative spacetimes. This interpretation is supported by a theorem stating that every non-Hausdorff manifold can be seen as a result of gluing together some Hausdorff manifolds.
After the talk all are welcome for dinner at Brown's (at your own expense) - please let James Read know by Wednesday 13th February if you would like to attend.
Philosophy of Physics Seminar Convenors for HT19: James Read and Simon Saunders