# Entropy: two short stories

Thermodynamics and statistical mechanics give us two alternative ways of thinking about entropy: in terms of heat flow, or in terms of the number of micro-states available to a system. John Chalker will describe a physical setting to illustrate each of these. By applying thermodynamics in a realm far beyond its origins, we can use the notion of an ideal heat engine to find the temperature of a black hole. And by applying combinatorial mathematics to hydrogen bonding, we can find the entropy of ice.