Norman Foster Ramsey

Norman Foster Ramsey, born in 1915, American physicist and Nobel Prize winner. Ramsey, with German American physicist Hans Georg Dehmelt and German physicist Wolfgang Paul, shared the 1989 Nobel Prize in physics for inventing a highly accurate technique for studying atomic-energy oscillations, which became the basis for modern atomic clocks.

Ramsey was educated at the University of Cambridge in England, and at Columbia University in New York City, where he received his Ph.D. degree in 1940 while working with Nobel Prize-winning physicist Isidor Isaac Rabi. For several years, Ramsey worked at various institutions, including the University of Illinois, and the Massachusetts Institute of Technology (MIT) Radiation Laboratory, and then joined the faculty at Columbia University. He was a member of the group of scientists that founded Brookhaven National Laboratory in New York, and served as the first chairman of Brookhaven's physics department. In 1947 he joined the faculty of Harvard University, where he spent the remainder of his career until his retirement in 1986.

Before Ramsey's work, atomic-energy oscillations were measured by passing a beam of atoms through a constant magnetic field. However, maintaining the magnetic field at a constant level over a large area proved difficult. Ramsey used two separate magnetic fields; as a result, he achieved vastly increased accuracy in the measurements. Called the separated-oscillatory-fields method, this technique put oscillations to use in synchronizing the components of atomic clocks, providing them with their remarkable accuracy. This method also was put to use in the creation of the first atomic maser (microwave amplification by stimulated emission of radiation), which is a focused beam of microwaves (similar to the light waves that form a laser). One of the maser's many applications was in space research, where it was used to track the space probe Voyager 2.

Ramsey's other notable research includes an explanation of chemical shifts in nuclear-magnetic-resonance (NMR) experiments. These shifts in the NMR experiments were explained by the presence of electrons around the nuclei. This understanding provided the basis for magnetic-resonance-imaging (MRI) instruments used in medicine. He also studied the interactions between atomic particles, and he measured the magnetic properties of these particles.