Equation 3 · Part 2 · The Arrow of Time and the Engine of Evolution
Symbol T
What this part means
the temperature.
Its job in the formula
T is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
Full expression→Symbol T→Article meaning
Where the article explains it
Rolf Landauer’s 1961 analysis established that any logically irreversible operation — one whose output does not determine a unique input, such as resetting a one-bit memory from either of two states to a single standard state — must, in an isothermal environment at temperature T , dissipate at least a fixed minimum quantity of heat to the surroundings: = T 2 per bit erased [ 3 ] .
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 variable is a named place for a value. Its letter is a local label: x can mean position in one formula and a data point in another.
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Sources cited in the surrounding passage
These citations provide research context; check each source for the exact claim it supports.