>I wonder what the limit of computing power per joule is Today you're going to learn that the universe puts a hard limit on this known as "Launder's principle"

>I wonder what the limit of computing power per joule is Today you're going to learn that the universe puts a hard limit on this known as "Launder's principle". To derive it in short, the (information) entropy on the input side of a single traditional logic gate is 2 bits, but on the output side it is just 1 bit. This seems to imply that the (physical) entropy of the computer would go down after the computation, because your computer had more possible physical states it could be in at the time of input than it seems to have at the time of output. But this is impossible as it violates the 2nd law of thermodynamics. To resolve the contradiction, each logic gate must be putting the missing bit of entropy on an untracked non-computational degree of freedom within the physical system. In other words the untracked "missing" information is encoded as seemingly random waste heat, and dumped into the environment at room temperature. https://en.wikipedia.org/wiki/Landauer%27s_principle https://en.wikipedia.org/wiki/Landauer%27s_principle