Nature: As the great quantum physicist Werner Heisenberg — he of the uncertainty principle — made plain, in quantum mechanics, separation of the observer from the phenomenon to be observed is not possible. But in fact, the strange idea that consciousness, intelligence and the act of observation are intertwined with physical phenomena predates Heisenberg. Specifically, James Clerk Maxwell famously introduced into his studies of thermodynamics "a being whose faculties are so sharpened that he can follow every molecule in its course", such that it could identify and siphon off the hotter (faster) molecules in a gas. 'Maxwell's demon' would thus be able to extract useful work from the system, while heat is in effect transferred from a cooler to a hotter region — in clear breach of the normal direction of heat flow from hotter to cooler encapsulated in the second law of thermodynamics.

In this week's Nature, Erez and others provide a neat link between these physical curiosities, by suggesting a way to use the quantum measurement process to control a system's thermodynamics, in the spirit of Maxwell's demon. At the heart of their concept is the quantum-physical equivalent of the old adage 'a watched pot never boils'. This is the quantum Zeno effect, which states that, if you measure a quantum system often enough, it will never be able to change its state, and so will not evolve at all.