Seminar: Heather Demarest

Heather Demarest is a professor of philosophy at the University of Colorado, Boulder.

Title: “Macrostates, Natural Kinds, and Statistical Mechanics”

Abstract: The second law of thermodynamics states that entropy (almost) always increases over time. However, different systems do this in very different ways. In some systems, like boxes of gas, entropy increases smoothly and uniformly. In other systems, such as refrigerators, crystals, trees, zebras, and human brains, entropy decreases in parts of the system, while increasing in other parts. A zebra (together with its environment) does not violate the second law, but there is an important sense in which the zebra resists (or perhaps more accurately, exploits) the second law. The zebra maintains or reduces its entropy by shunting its extra entropy into its environment. This is possible because the zebra consumes highly ordered, low-entropy energy (grass) and excretes higher entropy waste (heat and manure). In this paper, I defend a metaphysical account of this difference in terms of multiple realizability—the fewer microphysical realizers a kind has, the more it is able to resist the second law. I make this notion precise with functional information (Hazen 2007; Wong 2023) of macrostates in the phase space of statistical mechanics.