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Equation 3 · Part 1 · The Arrow of Time and the Engine of Evolution

Symbol k_B

kBTk_{\mathrm{B}}T
kBk_{\mathrm{B}}

What this part means

kBk_B is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

Its job in the formula

kBk_B is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

The passage around this formula

Charles Bennett used Landauer’s bound to close a hole that had troubled physicists since Maxwell first imagined a demon who could sort fast and slow molecules without doing work. Bennett’s 1982 review argued that a demon can, in principle, measure a molecule’s state without inevitable dissipation — measurement per se can be made close to thermodynamically reversible if implemented carefully. What the demon cannot do is remember indefinitely: with a memory of finite capacity, a demon that keeps operating must eventually erase old records to make room for new ones, and it is that erasure, governed by Landauer’s bound, that generates the entropy needed to save the second law [ 4 ] . Bennett’s…

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A subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.

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Sources cited in the surrounding passage

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