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
German-American condensed-matter physics
Rolf Landauer
1927 – 1999
IBM physicist whose 1961 paper established that logically irreversible operations — above all, erasing a bit — carry an unavoidable thermodynamic cost of at least kT ln 2 of heat per bit. His slogan, "information is physical", became the organising principle of the physics of computation.