Maxwell’s Demon: May the Force be With You

5 February 2007

Imagine being able to aim a pen at a small object, albeit a very, very small object, and moving the object along a sloped hill with an invisible ‘force.’ Such a possibility, once the domain of science fiction, is now within the realm of possibility thanks to a discovery by scientists in Scotland who have built a ‘nanomachine’ envisioned 150 years ago.

The nanomachine is modeled after a theoretical piece of engineering known as Maxwell’s Demon, named after the famous scientist by the same name, James Clerk Maxwell. Over a century ago he envisioned the possibility of a small, molecular demon-like creature that had the capability of trapping molecules as they moved along a certain direction. Specifically, he imagined two chambers filled with molecules, some moving at a rapid speed (thus creating heat), and others moving at a slow speed (thus creating cooler temperatures). The chambers would be separated by a gate, and a small ‘demon’ would act as a gatekeeper, with his sole purpose to trap the faster moving molecules into one chamber, and leaving the slower moving molecules in the other chamber. Thus, heat would exist in one chamber, and cold in the other, creating the perfect setup for a steam engine.

Well, through Nanotechnology, scientists have created an invention that approximates Maxwell’s vision. Physicists at the University of Edinburgh created a device that traps molecules as they move along a certain path, much as Maxwell predicted. The device is based on light to generate the initial energy. Future applications of the device would be for laser technology, where you could trap molecules in such a way as to create a ‘force’ in front of an object to move it along. Thanks to Nanotechnology, Maxwell’s demon has come of age.

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