Charles Bennett nsIn hmolscience, Charles Bennett (1943-) is an American computational molecular dynamics researcher noted, in computer thermodynamics, whose name is oft-cited in discussions about information, energy, and entropy.

Overview
In circa 1970, Bennett came across one of German-born Rolf Landauer’s 1961 paper on an attempt to prove experimentally American chemical engineer John Neumann’s 1949 folklore lecture comment that:

“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.”

Bennett then began working on this problem on his own and in 1973, in his own words, “showed that general purpose computation can be performed by a logically and thermodynamically reversible apparatus, one which is able to operate with arbitrarily little energy dissipation per step because it avoids throwing away information about past logical states.” This statement, however, seems to be a mistranslation of thermodynamics, according to which the second law states that all natural processes are irreversible.

In the 1970s, he did work on constructing or theorizing about an “irreversible computer”, i.e. one that does not show an entropy increase during computation processes, such as in the erasure of one bit of information.

His 1988 article “Notes on the History of Reversible Computation”, gives a fairly decent summary of the history of the overlap of ideas on information, entropy, and computer processing theory.

In 1982, Bennett proposed a reinterpretation of Maxwell’s demon, attributing its inability to break the second law to an irreducible thermodynamic cost of destroying, rather than acquiring, information.

In 1987, Bennett gave an artistic rendition of Szilard's demon. [3]

Soul weighting
See main: Soul weight
American chemical engineer Gerard Nahum 1988 article “A Proposal for Testing the Energetics of Consciousness and its Physical Foundation” cites Bennett, along with Claude Shannon (1949) and Alvin Weinberg (1982), as being justification for the view that the following expression:

 \Delta Q_{bit} \le - T k \ln 2 \!

quantifies heat loss per loss of bit of information in the nervous system, and uses this equation as a means to justify the idea that the soul of the person can be quantified and measured at the time of death. [2]

Education
Bennett competed his PhD in 1970 on molecular dynamic studies, specifically computer simulation of molecular motion, at Harvard University.

References
1. Bennett, Charles H. (1988). “Notes on the History of Reversible Computation”, IBM J. Res. Develop. 32(1): 16-23.

Further reading
1. Bennett, Charles H. (1982). “The Thermodynamics of Computation: a Review”, Int J Theor Phys, 21: 905-40.
2. (a) Shannon, Claude and Weaver, W. (1949). The Mathematical Theory of Communication. University of Illinois Press.
(b) Bennett, Charles H. (1982). “The Thermodynamics of Computation: a Review”, Int J Theor Phys, 21: 905-40.
(c) Weinberg, Alvin M. (1982). “On the Relation between Information and Energy Systems”, Interdisc Sci rev, 72: 47-52.
(d) Nahum, Gerard. (1998). “A Proposal for Testing the Energetics of Consciousness and its Physical Foundation (25-pgs)”, Presented at an international meeting in Tuscson, AZ called Tuscon III: Towards a Science of Consciousness.
(e) ibid, Nahum. (2005). “A Proposal for Testing the Energetics of Consciousness and its Physical Foundation (33-pgs)”, Submitted for review to Consciousness and Cognition.
(f) Nahum, Gerard. (2010). “A Proposal for Testing the Energetics of Consciousness and its Physical Foundation”, Journal of Human Thermodynamics, 6: 1-25, March.
3. Bennett, Charles H. (1987). “Demons, Engines, and the Second Law”, Scientific American, 257(5): 108-116, Nov.

External links
Charles Bennett (computer scientist) – Wikipedia.
Charles H. Bennett (publications) – Research.IBM.com.

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