The Unparalleled Genius of John von Neumann
von Neumann, Oppenheimer, Bohr, Einstein, Rutherford, Turing,  Teller, Szilard, Wigner, Meitner... the list goes on... -- how did that time produce so many people of colossal intellect?
War certainly can't be the primary factor, given that many of them were brilliant/productive even before WWI