> According to current theory of physics, every computation needs at least a certain amount of energy. This is not, strictly speaking, true. You are talking, I

> According to current theory of physics, every computation needs at least a certain amount of energy. This is not, strictly speaking, true. You are talking, I believe, about Lanadauer's principle [1]. This states that it is the destruction of entropy that costs energy. There are computational methods that can theoretically avoid these energy losses [2]. In fact, Lanadaer theorized about reversible computing in his original paper [3]. Bremmerman's limit, mentioned below, is more applicable. 1. http://en.wikipedia.org/wiki/Landauer%27s_principle http://en.wikipedia.org/wiki/Landauer%27s_principle 2. http://en.wikipedia.org/wiki/Reversible_computing http://en.wikipedia.org/wiki/Reversible_computing 3. http://www.cc.gatech.edu/computing/nano/documents/Bennett%20-%20The%20Thermodynamics%20Of%20Computation.pdf http://www.cc.gatech.edu/computing/nano/documents/Bennett%20...