The Paradox of Boltzmann's Theory

In the late 19th century, Boltzmann proposed successfully that thermodynamics was not fundamental because matter was made of atoms. The laws of thermodynamics could be explained as being emergent from the behavior of atoms where the atoms follow fundamental laws of motion. But there was a paradox inherent in his reasoning which people at the time identify. And this was worked out by the iron fest, Paul and Tatania Ironfest,. who were dear friends of Einstein around 1905, 1908, or somewhere around then.