Tuesday 13th October 2026, 6.30pm, Chipperfield Lecture Theatre
Prof. Ian Ford (University College London)
It is perfectly reasonable to be puzzled by the second law of thermodynamics with its claim that the entropy of a closed system should either increase with time or at best stay the same, mainly because the rules of dynamics according to Newton and Schrodinger do not designate a preferred direction in time. Why should entropy (whatever that is) be so selective? In 1867, motivated by this puzzle, James Clerk Maxwell invented a thought experiment that broke the second law, featuring the actions of his famous (and fictional) ‘demon’. But is the demon actually breaking the law, or just faking it? We shall review the way in which the demon operates and try to clarify what is going on. And along the way, we shall pin down what entropy actually represents.
About the speaker
Ian Ford is Emeritus Professor of Physics at UCL, and has worked on various topics in the statistical mechanics of condensed matter, particularly the nucleation of molecular clusters from metastable parent phases and the formation of polymer phases. He has most recently studied the irreversibility of quantum measurement using methods of stochastic thermodynamics. Entropy production is the common thread that links these disparate fields and his undergraduate textbook ‘Statistical Physics: an Entropic Approach’ is an attempt to demystify the concept.
The talk is free and open to all. Doors open about half an hour before the talk begins.
For directions to the lecture theatre, see here.