### Abstract

When we drive a physical system away from a state of thermal equilibrium by forcing a change in one of its variables -- e.g. when we push a piston into a gas, or when we stretch a single molecule using optical tweezers -- then we perform a certain amount of work, W, on the system.

Over the past decade, a number of results -- collectively known as nonequilibrium work theorems (NWT's) -- have revealed that equilibrium information is subtly encoded in the statistics of W, even when the system is driven significantly far from equilibrium.

In my three lectures I will present an introduction to these theoretical results, as well as to their applications in the context of experiments and numerical simulations aimed at estimating thermodynamic properties of complex systems. The first lecture will present a general overview of these results. In the remaining two lectures I plan to cover a number of topics, including: useful mathematical tools for deriving and analyzing NWT's; practical issues regarding the applications of these results; generalizations of NWT's, and their relation to Fluctuation Theorems; and the connection of NWT's to deeper issues of macroscopic irreversibility.