GRG18 Day 2

Only Day 2 and I've started drinking coffee again, mostly to help down large quantities of cake. This morning started with a talk by B. Krishnan on Black Hole horizons, which moved quite quickly into definitions related to trapped surfaces from a short introduction on the need to move beyond event horizons. There are important applications to numerical relativity because one cannot locate event horizons. I confess to skipping the second talk for more coffee and cake and a pleasant conversation with a lady from Brisbane and the opal lady from the exhibition section.

Last up this morning we heard from Eisenstein on "Observing Dark Energy". He explained nicely his lack of theoretical prejudice as to the cause, but that wasn't until half way through the talk. The first half of the talk summarised in general terms a long list of evidence for apparent acceleration, including the supernovae, CMB acoustic scale, cluster abundances, cluster baryon mass fractions, galaxy-galaxy weak lensing and large scale structure. Having given the impression that he took all this as evidence for a cosmological constant, at question time he was bombarded with comments from D. Wiltshire, A. Vilenkin and I. Neupane.