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Equation 9 · Part 2 · From Origins to Frontier: A History of Stochastic Thermodynamics and Complex Systems

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ΔF\Delta F
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What this part means

Capital delta attached to a quantity marks a difference between two values of that quantity; the article’s sign convention determines the order.

Its job in the formula

Capital delta attached to a quantity marks a difference between two values of that quantity; the article’s sign convention determines the order.

The passage around this formula

The next structural advance did not concern the demon at all; it concerned a much older and more general problem — how to extract equilibrium information from a process driven arbitrarily far from equilibrium. In 1997, Christopher Jarzynski published “Nonequilibrium Equality for Free Energy Differences” in Physical Review Letters [ 3 ] . The Jarzynski equality states that if a system is driven from one equilibrium state to another along some protocol, performing a fluctuating amount of work W on each repetition, the equilibrium free energy difference Δ\Delta F between the two states can be recovered exactly from an exponential average over the work distribution:

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Learn the underlying idea

Addition combines quantities; subtraction measures the signed difference between them. Parentheses show what is combined before the rest of the expression is evaluated.

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Sources cited in the surrounding passage

These citations provide research context; check each source for the exact claim it supports.