Rolf Landauer nsIn computer science, Rolf Landauer (1927-1999) was a German-born American physicist noted for

Overview
In circa 1960s, Landauer attempted to prove American chemical engineer John Neumann’s 1949 folklore lecture idiom that: [1]

“A computer operating at a temperature T must dissipate at least kT ln 2 of energy per elementary act of information, that is, per elementary decision of a two-way alternative and per elementary transmittal of one unit of information.”

Research on this subject resulted in his 1961 article “Irreversibility and Heat Generation in Computer Process”, which culminated in what has come to be known as Landauer's principle, the idea that energy has to be expended to erase information or in other words that entropy is generated in computer processing actions, in accordance with the second law.

Landauer argues in his high-cited 1961 article that: "computing machines inevitably involve devices which perform logical functions that do not have a single-valued inverse. This logical irreversibility is associated with physical irreversibility and requires a minimal heat generation, per machine cycle, typically of the order of kT for each irreversible function." [2]

This seems to be one of the first attempts to link the famous Boltzmann entropy formula S = k ln W with computational processing.

Education
Landauer completed his SB (1945), AM (1947), and PhD (1950), the latter in physics, all at Harvard University. He then worked as a physicist at the National Advisory Committee for Aeronautics at Lewis Laboratory for two years after which in 1952 he joined on as a physicist at IBM.

References
1. Bennett, Charles H. (1988). “Notes on the History of Reversible Computation”, IBM J. Res. Develop. 32(1): 16-23.
2. Landauer, Rolf. (1961). “Irreversibility and Heat Generation in Computer Process” (abs), IBM J. Res. Develop, 3: 183-91.

Further reading
● Thims, Libb. (2012). “Thermodynamics ≠ Information Theory: Science’s Greatest Sokal Affair” (url), Journal of Human Thermodynamics, 8(1): 1-120, Dec 19.

External links
Rolf Landauer – Wikipedia.
Rolf Landauer – AIP.org.

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