Maxwell's Demon
A tiny creature sorting fast molecules from slow ones appears to make heat flow the wrong way, for free, forever.
1867 (letter to Tait), 1871 (published in Theory of Heat)18 min read
Hungarian-American physics
Leó Szilárd
1898 – 1964
Physicist who conceived the nuclear chain reaction in 1933, drafted the letter Einstein sent to Roosevelt in 1939, and later campaigned against the weapons he had helped make possible. His 1929 paper on Maxwell's demon reduced the problem to a single-molecule engine and argued that the demon's act of acquiring information must itself generate entropy — the first quantitative link between information and thermodynamics.