In the first half of the 20th century the world had people like Hilbert, Bohr, Von Neumann, Einstein, Feynman, Fermi, Gödel, Noether, Oppenheimer, Erdos, Dirac, Poincaré, etc.

Where are these types of people today? We have Perelman and Wiles. Maybe Maldacena or Arkani-Hamed?

Was the early 20th century a unique period of fertile scientific ground just waiting to be uncovered by smart people or was there an unusually high supply of gifted scientists in that era?