ABSTRACT
In pursuit of scientific inquiry into the physics of the universe, one encounters a phase at which reversibility plays an important role. Quantum mechanics and the Maxwell’s Demon are some salient indicators of this intriguing facet of Nature. Equally intriguing, a pursuit of scientific inquiry into the thermodynamic limits of computing also leads to the role of reversibility in terms of information represented in physical processes. A provocative discussion by Charles Bennett titled “Is Information Physical or Physics Informational?”
highlights, among other things, this uncanny yet critical relation [Bennett, 2005]. Thus, strangely, reversibility appears in the center of both concepts (see Figure 4.1): the informational aspects of phenomena in physics and the energy limits in the physics of computation. Historically, the former was investigated in great depth in relation to physical systems as varied as steam engines and astrophysical bodies. Along the way, principles that transcend almost all technology-specific details evolved in the form of concepts such as entropy and laws of thermodynamics. Much later, the latter appeared when the physical needs of information processing were investigated in the context of energy-efficient computation.
