In the first half of the 20th century, a considerable number of famous scientists emigrated from Hungary to the United States, including physicists Eugene Wigner, Edward Teller, and Dennis Gabor and mathematicians Theodore von Kármán, John von Neumann, Paul Halmos, George Pólya, and Paul Erdős. Most were Jewish refugees from Nazi Germany, but they had surprising further similarities — many had been born near Budapest, had shown an early interest in chemistry, and had studied physics at German universities before emigrating to America. One of their number, Leo Szilard, joked that he knew the reason: They were all descended from...