The idea that matter is made of indivisible particles (átomos in Greek) goes back to Democritus (5th century BC), but for over two thousand years it remained a philosophical speculation, without any experimental basis. The first step towards a physical theory was taken by Daniel Bernoulli in 1738, who was the first to propose that the pressure of a gas is due to particle collisions with the walls: this is the seed of kinetic theory (Simonyi 2012, ch. 4).
The idea was taken up and formalised only a century later by Rudolf Clausius (1857) and James Clerk Maxwell (1860), who derived the statistical distribution of molecular speeds. Ludwig Boltzmann (1844–1906) brought the theory to completion by linking entropy to the number of microstates:
Tragically, Boltzmann took his own life in 1906, a few years before Jean Perrin’s experiments on Brownian motion (1908) definitively confirmed the existence of atoms (Brandt 2009, ch. 5).
Historical context
Bernoulli (1738) → Clausius (1857) → Maxwell (1860) → Boltzmann (1872) → Perrin (1908). Over two thousand years passed from the philosophical insight to the experimental proof: kinetic theory is one of the longest bridges between idea and measurement in the history of science. See also Riferimenti bibliografici.
Links
Topics: Teoria cinetica dei gas Concepts: Entropia
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