Information is Physical

MAY 01, 1991

There are no unavoidable energy consumption requirements per step in a computer. Related analysis has provided insights into the measurement process and the communication schannel, and has prompted speculations about the nature of physical laws.

DOI: 10.1063/1.881299

Rolf Landauer

Thermodynamics arose in the 19th century out of the attempt to understand the performance limits of steam engines in a way that would anticipate all further inventions. Claude Shannon, after World War II, analyzed the limits of the communications channel. It is no surprise, then, that shortly after the emergence of modern digital computing, similar questions appeared in that field. It was not hard to associate a logic gate with a degree of freedom, then to associate kT with that, and presume that this energy has to be dissipated at every step. Similarly, it seemed obvious to many that the uncertainty principle, $ΔEΔt∼ℏ,$ could be used to calculate a required minimal energy involvement, and therefore energy loss, for very short $Δt.$

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More about the Authors

Rolf Landauer. Thomas J. Watson Research Center, Yorktown Heights, New York.