Neils Bohr

It was 1943, and a man sat nervously in the belly of a British military plane, flying over Nazi-occupied Europe. The stakes then were higher than they had ever been.

His coat concealed no weapon or codebook, but something far more dangerous — his mind. His name was Niels Bohr, and he had just escaped from Denmark, smuggled out of the reach of the Nazis, whose war machine had long taken an interest in scientific genius.

Bohr was a quiet revolutionary. The sort of person who always seemed more at home with equations than with people, yet when he talked could light up a room.

He possessed a barely believable knack for spotting the invisible. He gazed upon the atom—not as a physicist eager to unlock its secrets but as a philosopher questioning the very nature of reality.

To understand what Bohr did, you need to know what the world was like without him. Physics was having an identity crisis in the early 20th century.