Hi, On the context of Maxwell's Demon, it's accepted that Landauer's principle (the erasure of a bit of information requires kTln2 of work) gives a solution to the paradox. The erasure of a bit of information can be seen as the modulation of a double well potential, as in the right side of the red line in the picture. It's also accepted that measurement can be done without energy expenditure. This was stated by Bennett, who proposed a measuring system just like the one on the left of the red line. Don't worry about the system itself: the important part is that the process can be represented by a double well potential being modulated just like it's drawn next to it. Well, as far as I can see, both double well potentials undergo the same procedure, yet the left one describes a process with supposedly no energy expenditure and the right one a process with kTln2 of energy expenditure. What am I missing?