It's back to basics with a consideration of Maxwell's demon and his
attempts to subvert the second law by telling us the outcome of a
measurement so that we can exploit, thermodynamically, the consequent
reduction in our ignorance. This time, the framework is stochastic
thermodynamics, where entropy production is defined in terms of the
probabilities that the dynamics generate a path and its time-reversed
counterpart. The bottom line is that work has to be performed by the
demon, with potential energy dissipated as heat, in order to acquire the
knowledge that can subsequently be exploited. The management of our
ignorance by the demon is entirely in line with the second law, and
without any need to appeal to a final resetting of the demon's memory
along the lines proposed by Bennett in 1982.