Philosophy of Physics Seminar (Thursday - Week 1, TT26)

Abstract: The past decade has seen a substantial philosophical debate on the status of black hole thermodynamics (BHT). In response to Dougherty and Callender, Wallace has argued that “black holes are thermodynamic systems in the fullest sense”, but there remain clear disanalogies, such as the lack of a pressure-volume term in the first law and the apparent non-extensivity of BHT. In this talk I will advocate for a recent proposal, based on York’s quasi-local thermodynamics, that defines the pressure and volume of a black hole “holographically” by enclosing the black hole in a cavity. This strengthens the case for BHT, as it both completes the first law with a proper pressure-volume term and shows that various black holes do indeed become extensive in the large-system limit, as is expected for usual thermodynamic systems. I include an in-depth discussion of the notion of extensivity in equilibrium thermodynamics, and argue that its application to black holes forces us to conclude that extensivity depends both on the equilibrium branch and thermodynamic representation considered.

Registration: If you do not hold a university card, please contact the seminar convenor or admin@philosophy.ox.ac.uk at least two working days before a seminar to register your attendance.