Pauling’s guide to quantum physics was Arnold Sommerfeld, whose institute at the University
of Munich was a nerve center for new ideas about the structure of atoms. Short and
slight, but still a commanding figure with his waxed moustache and dueling scar, Sommerfeld
had a knack for turning out some of the best scientific minds of his day. He corresponded
with all the leading physicists, was visited by many, and made his classes into exercises
in cutting-edge thinking.
When Pauling arrived in Munich on his Guggenheim Fellowship in 1925, Sommerfeld’s
institute was abuzz with news of a radically new approach toward understanding the
atom that had been proposed by one of Sommerfeld’s former students, a young physicist
Heisenberg. Conceived during a rapturous solo vacation on a windswept island in the
North Sea, Heisenberg’s approach replaced all physical ideas about the atom with pure
mathematics. His work caused a furor among traditional physicists, who thought it
absurd to form a theory without a physical picture of the atom behind it.
But then, just as the Paulings were settling into a tiny Munich apartment, a seemingly
new, very different approach was presented by one of Heisenberg’s critics, the Austrian
physicist Erwin Schrödinger. The two competing theories were the subject of heated
debate during the entire time Pauling was in Europe. But he quickly decided which
one appealed to him most.