Minsta möjliga energi ändra 1 --> 0

One of the consequences of the second law of thermodynamics is that a certain amount of energy is necessary to represent information. To record a single bit by changing the state of a system requires an amount of energy no less than kT, where T is the absolute temperature of the system and k is the Boltzman constant. (Stick with me; the physics lesson is almost over.)

http://www.schneier.com/blog/archives/2009/09/the_doghouse_cr.html