Posts tagged #Information
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Maxwell's demon, taken seriously
An imaginary being watching a single molecule seems to extract work out of nothing, in defiance of the second law of thermodynamics. Dissolving the paradox took a century and a new idea: information is physical. Shannon's entropy of messages and Boltzmann and Gibbs's entropy of molecules answer the same question, Landauer's principle fixes the exchange rate between the two, and Szilárd's engine puts it to the test: how much a bit weighs, where it ends up when it is erased, and why there is no free lunch either way.