Maxwell's Demon

Maxwell's Demon

Having read of Sir Michael Atiyah’s commitment to raising the profile of James Clerk-Maxwell in Scotland, RSE Fellow, Professor David Leigh contacted the Society to voice his support and to share information about related work he is pioneering.

Professor Leigh and his team at the University of Edinburgh’s Chemistry department have achieved the experimental realisation of a version of the famous ‘thought-experiment’, Maxwell’s Demon, conceived by Clerk-Maxwell nearly 140 years ago.

Professor Leigh and his team at the University of Edinburgh’s Chemistry department have achieved the experimental realisation of a version of the famous ‘thought-experiment’, Maxwell’s Demon, conceived by Clerk-Maxwell nearly 140 years ago.

Professor David Leigh

Professor Leigh explains: What we’ve made is a molecule with two compartments separated by a molecular ‘trapdoor’. Located in one of the two compartments is a molecular ring. When light is shone on the system, a mechanism operates such that if the ring is in the left-hand compartment the trapdoor opens momentarily and the ring can sometimes pass through to the right-hand compartment by Brownian motion before the trapdoor closes. If the ring is in the right-hand compartment, however, the trapdoor rarely opens, even when the light is shining.

The net effect is that for an ensemble of molecules the rings tend to accumulate in the right- hand compartment, driving the statistical distribution away from thermodynamic equilibrium just like in Maxwell’s celebrated thought experiment. The big difference between our ‘real’ system and Maxwell’s imaginary one, of course, is that our experimental set-up requires an input of energy (light) which means our molecules are not some kind of perpetual motion machine, they need a fuel just like any other engine. Indeed, the reason for doing this sort of research is not to try to violate the Second Law of Thermodynamics, but rather to come up with new motor-mechanisms for artificial nanomachines.

Many believe that nanotechnology will have the same sort of impact on our society and economy as the steam engine, the transistor and the internet. We believe these sorts of molecular machines will help power this revolution.

 

 

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