Philosophy of Physics Seminar (Thursday - Week 1, MT24)

Abstract: The 'Past Hypothesis', as advocated by David Albert and Barry Loewer, is the hypothesis that the world came into being in whatever particular low-entropy highly-condensed big-bang sort of macrocondition it is that the normal inferential procedures of cosmology will eventually present to us. I consider some hypotheses about what that macrocondition is likely to be given what cosmology has already presented to us, and explore the consequences of these hypotheses for the broader ('Mentaculus') project of grounding physics and the special sciences in the Past Hypothesis. My main conclusion is that current cosmology suggests a unique, pure quantum state (the local quantum vacuum, or 'Bunch-Davies vacuum') for the initial state of the Universe, in which case statistical-mechanical probabilities emerge from quantum probabilities without any need for an intervening statistical postulate.