Maxwell demon

noun

, Physics.

1. a hypothetical agent or device of arbitrarily small mass that is considered to admit or block selectively the passage of individual molecules from one compartment to another according to their speed, constituting a violation of the second law of thermodynamics.

Word History and Origins

Origin of Maxwell demon¹

First recorded in 1875–80; after J. C. Maxwell

Example Sentences

However, if the part of the system implementing the demon is disregarded, everything looks as if the remaining pat of the system was subjected to a Maxwell demon breaking the second law while keeping the first one intact.”

From Scientific American