Reversible computing
I have often heard that erasing (not storing) data is what unavoidably consumes energy. I never heard quite so picturesque an explanation of why as this one, seen on slashdot:
For example, when a computer erases something, what it does physically is ground one part of a circuit that holds a charge, in effect converting the stored energy -- and the information it represents -- into heat, Frank said. When chips perform millions or billions of erasing and other operations in a short time, the total heat becomes substantial, limiting both the performance of the chip and the number of chips that can be packed together in a small space, he said.
