Book excerpt: Most scientists and engineers are familiar with the name Josef Stefan primarily from the Stefan-Boltzmann law, which relates the amount of energy transferred by radiation to the absolute temperature raised to the fourth power. Stefan determined this law from experimental data, and it was later theoretically verified by his former student, Ludwig Boltzmann. However, it is interesting to know that this is the same Stefan who lent his name to the solid-liquid phase change problem, and concepts related to molecular diffusion and convective motion driven by surface evaporation or ablation. Stefan counted among his students Sigmund Freud, who was so inspired by his physics instructor that he incorporated scientific methods into psychoanalysis. This invaluable book details not only Josef Stefan’s original contributions in these areas, but the current state-of-the-art of his pioneering work.