Philosophy of Physics Seminar (Thursday - Week 1, MT23)

Philosophy of Physics

Working inside the control-theoretic framework for understanding thermodynamics, I develop a systematic way to characterize thermodynamic theories via their compatibility with various notions of coarse-graining, which can be thought of as parametrizing an agent's degree of control of a system's degrees of freedom, and explore the features of those theories. Phenomenological thermodynamics is reconstructed via the `equilibration' coarse-graining where a system is coarse-grained to a canonical distribution; finer-grained forms of thermodynamics differ from phenomenological thermodynamics only in that some states of a system possess a free energy that can be extracted by reversibly transforming the system (as close as possible) to a canonical distribution. Exceeding the limits of phenomenological thermodynamics thus requires both finer-grained control of a system and finer-grained information about its state. I consider the status of the Second Law in this framework, and distinguish two versions: the principle that entropy does not decrease, and the Kelvin/Clausius statements about the impossibility of transforming heat to work, or moving heat from a cold body to a hotter body, in a cyclic process. The former should be understood as relative to a coarse-graining, and can be violated given finer control than that coarse-graining permits; the latter is absolute, and binds any thermodynamic theory compatible with the laws of physics, even the entirely reversible limit where no coarse-graining is appealed to at all. I illustrate these points via a discussion of Maxwell's demon.

With speaker’s consent, talks will be recorded and published on YouTube. Our channel is:

https://www.youtube.com/c/OxfordPhilosophyofPhysics/videos

If you wish to join the dinner following the talk, please email Oliver Pooley: oliver.pooley@philosophy.ox.ac.uk.


Philosophy of Physics Seminar Convenors for MT23: Oliver Pooley, Patrick Duerr and Henrique de Andrade Gomes  | Philosophy of Physics Group Website