The field of nuclear physics depends upon a working knowledge of atoms and atomic structure. In 1937, Isodor Isaac Rabi was the first to observe the effect known as nuclear magnetic resonance (NMR) in atoms of silver. Before this time, scientists knew that atomic nuclei spun, but no reliable process yet existed by which the magnetic strengths of atoms could be measured. Rabi's discovery paved the way for modern nuclear physics.

Rabi had taken a sample of silver and vaporized it. The vapor was shot through an alternating magnetic field; this caused the spinning nuclei within the metal's atoms to "wobble," much like a spinning top, which wobbles as gravity pulls on it. He then introduced a radio signal, varying the frequency until the silver atoms' nuclei all reversed their spin spontaneously; this reversal of spin is called nuclear magnetic resonance, since it...