Flukessa: Fluctuation Theorem Entropy
Thermodynamics & Statistical Physics arc, page 48 of 193. Back to The Pixelated Physics Universe
Who they are
Flukessa has one line, and says it often: “Second law: briefly, in my favour.”
Flukessa is a character of the Thermodynamics & Statistical Physics arc: drawn in pixels, ruled by one piece of real physics, and never allowed to break it.
The physics
Fluctuation theorem: small systems can briefly show entropy decrease with exponentially small probability.
$$ \begin{gathered} \frac{P(\Sigma_t = A)}{P(\Sigma_t = -A)} = e^{A t} \end{gathered} $$
| Symbol | Meaning | SI unit |
|---|---|---|
| $\Sigma_t$ | time-averaged entropy production rate over time t (units of k_B) | s^{-1} |
| $A$ | value of the entropy production rate | s^{-1} |
| $t$ | averaging time | s |
Sources
- D. J. Evans, E. G. D. Cohen & G. P. Morriss, PRL 71, 2401 (1993)
- G. M. Wang et al., PRL 89, 050601 (2002)
Crossovers
Flukessa meets Jarza (Jarzynski Equality). Jarza and Flukessa share a family: both are exact statements about fluctuations far from equilibrium. On average, the second law still holds for each of them.
Flukessa meets Dissipar (Fluctuation Dissipation Theorem). Dissipar reads a system's response from its equilibrium fluctuations. Flukessa's theorem extends that bookkeeping far from equilibrium. Near equilibrium, the two agree.
Wear the lore
Concept keywords: Fluctuation Theorem Entropy, Flukessa, Thermodynamics & Statistical Physics, physics lore, Pixelated Physics