Planck had received his PhD for an analysis of the second law of thermodynamics. Like Mach and Ostwald, he disapproved of Boltzmann’s insistence on the reality of atoms and molecules and that their behavior underpinned the second law. In 1882, he explicitly declared Boltzmann was wrong, writing, “The second law of the mechanical theory of heat is incompatible with the assumption of finite atoms.… A variety of present signs seems to me to indicate that atomic theory, despite its great successes, will ultimately have to be abandoned.”
