Caption: At the tomb of Boltzmann.

Ludwig Boltzmann (1844--1906) was a pioneer of thermodynamics, statistical mechanics, 2nd law of thermodynamics, and entropy---the precise measure of disorder.

Boltzmann's most famous formula for entropy (and the most concise formula for entropy) is engraved on his gravestone:

      S = k ln(W) ,

where S is entropy, k is Boltzmann's contant (k = 8.6173324(78)*10**(-5) ≅ 10**(-4) eV/K), ln is the natural logarithm function (same as log in this context), and W is the number of microstates (see Wikipedia: Entropy: Statistical Mechanics).

And another thing: if you wake up some morning thinking that everything is an illusion, then you might be a Boltzmann brain.

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