When Ernest Rutherford introduced him to the Danish Nobel laureate Niels Bohr at a university conference, he was delighted and the conversation with him restored his confidence in his own abilities and skills. He decided to pursue theoretical physics.

He chose to go to the world center of theoretical physics - the University of Göttingen, where he continued his studies with one of the founders of quantum mechanics, Max Born. At the university he also met many other prominent figures, including Werner Heisenberg, Enrico Fermi, Edward Teller, Pascual Jordan, Wolfgang Pauli, Paul Dirac.