Maxwell's demon
From Conservapedia
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Maxwell's demon is a hypothetical being invoked in a thought experiment that illustrates the second law of thermodynamics. In the thought experiment there is a gas-filled container with two chambers and a small trap door in the partition between them. The 'demon' opens and closes the door to collect faster moving gas molecules in one chamber and slower ones in the other chamber, creating a difference in temperature between the two chambers. It is named after James Clerk Maxwell who developed the thought experiment.
