In 1926, Enrico Fermi published “On the Quantization of the Perfect Monatomic Gas,” in which he exploited the Pauli exclusion principle, formulated just a year earlier, for a system of particles. The article immediately received widespread attention. The international conference commemorating the centenary of Alessandro Volta’s death (Como, 1927) was attended by leading scientists such as Bohr, Planck, Heisenberg, Pauli, and Sommerfeld; the latter gave a lecture explaining the application of Fermi’s statistics to conduction electrons in metals, contributing to the Italian physicist’s fame. Heisenberg apparently introduced Fermi to Pauli with these words: “I present to you the application of the exclusion principle.” In 1926, Paul Dirac addressed the same problem and independently developed a slightly different method that reached the same conclusions. Fermi, reading Dirac’s paper, was puzzled to see that there was no reference to his work and wrote him a letter on October 25: “In your interesting paper on the theory of quantum mechanics you propose a theory of the ideal gas based on the Pauli exclusion principle. Now, a theory of the ideal gas which is practically identical to yours was published by me early in 1926. Since you have not seen my paper, I imagine, I beg you to take it into consideration.” Dirac immediately sent Fermi an apologetic message and always referred to it, from then on, as Fermi-Dirac statistics, attributing much of the authorship to the Italian physicist. Dirac later explained: “When I leafed through Fermi’s paper, I remembered that I had seen it before, but had completely forgotten about it. Unfortunately, I have a rather bad memory; things can slip my mind completely if I don’t immediately realize their importance. When I read Fermi’s paper, I didn’t understand its relevance to all the fundamental problems of quantum mechanics: it seemed to me to be a completely unrelated work. It had just slipped my mind, and when I wrote my paper on antisymmetric wave functions, I had no memory of it at all.”
