Albert Einstein liked coming to Leiden, the Dutch city particularly known for its venerable university. Vienna-born theoretical physicist Paul Ehrenfest, professor at Leiden University since 1912, was one of his closest friends. 1
Last July Rowdy Boeyink, a history-of-science student, stumbled across a long-lost, handwritten Einstein manuscript in the Ehrenfest Library of Leiden University’s Lorentz Institute for Theoretical Physics. The manuscript was part two of a paper entitled “Quantum Theory of Monatomic Ideal Gases,” which Einstein presented at a 1925 meeting of the Prussian Academy of Sciences. 2
That paper has a special significance. It contained Einstein’s last great discovery—Bose–Einstein condensation, as the effect came to be called. Unearthed amid the celebrations of the Word Year of Physics, the centenary of Einstein’s 1905 annus mirabilis, the 16 handwritten pages attracted international media attention. 3 That same month, Boeyink also found among Ehrenfest’s papers typescripts of two more Einstein papers—one from...
