"A so-called logically reversible computation, in which no information is erased, may in principle be carried out without releasing any heat. This has led to considerable interest in the study of reversible computing. Indeed, without reversible computing, increases in the number of computations per joule of energy dissipated must come to a halt by about 2050, because the limit implied by Landauer's principle will be reached by then, according to Koomey's law."