Norman Foster Ramsey

Norman Foster Ramsey Jr. (August 27, 1915 – November 4, 2011) was an American physicist who was awarded the 1989 Nobel Prize in Physics for the invention of the separated oscillatory field method (see Ramsey interferometry), which had important applications in the construction of atomic clocks. A physics professor at Harvard University for most of his career, Ramsey also held several posts with such government and international agencies as NATO and the United States Atomic Energy Commission. Among his other accomplishments are helping to found the United States Department of Energy's Brookhaven National Laboratory and Fermilab.

Early life Norman Foster Ramsey Jr. was born in Washington, D.C., on August 27, 1915, to Minna Bauer Ramsey and Norman Foster Ramsey. His mother was the daughter of German immigrants and an instructor at the University of Kansas. His father, who was of Scottish descent, was a 1905 graduate of the United States Military Academy at West Point and an officer in the Ordnance Department who rose to the rank of brigadier general during World War II, commanding the Rock Island Arsenal. He was raised as an Army brat, frequently moving from post to post, and lived in France for a time when his father was Liaison Officer with the and Assistant Military Attaché. This allowed him to skip a couple of grades along the way, so that he graduated from Leavenworth High School in Leavenworth, Kansas, at the age of 15. Columbia awarded him a Kellett Fellowship to Cambridge University, where he studied physics at Cavendish Laboratory under Lord Rutherford and Maurice Goldhaber, and encountered notable physicists, including Edward Appleton, Max Born, Edward Bullard, James Chadwick, John Cockcroft, Paul Dirac, Arthur Eddington, Ralph Fowler, Mark Oliphant and J. J. Thomson. Soon after Ramsey arrived at Columbia, Rabi invented molecular-beam resonance spectroscopy, for which he was awarded the Nobel Prize in Physics in 1944. Ramsey was part of Rabi's team that also included Jerome Kellogg, Polykarp Kusch, Sidney Millman and Jerrold Zacharias. Ramsey worked with them on the first experiments making use of the new technique and shared with Rabi and Zacharias in the discovery that the deuteron was a magnetic quadrupole. This meant that the atomic nucleus was not spherical, as had been thought. He received his PhD in physics from Columbia in 1940

The Harvard cyclotron during construction in 1948. Shown are Ramsey (left) and Lee Davenport (right).

Ramsey's research in the immediate post-war years looked at measuring fundamental properties of atoms and molecules by use of molecular beams. On moving to Harvard, his objective was to carry out accurate molecular-beam magnetic-resonance experiments, based on the techniques developed by Rabi. However, the accuracy of the measurements depended on the uniformity of the magnetic field, and Ramsey found that it was difficult to create sufficiently uniform magnetic fields. He developed the separated oscillatory field method in 1949 as a means of achieving the accuracy he wanted. He was awarded the Nobel Prize in Physics in 1989 "for the invention of the separated oscillatory fields method and its use in the hydrogen maser and other atomic clocks". The Prize was shared with Hans Georg Dehmelt and Wolfgang Paul. He was an elected member of the American Academy of Arts and Sciences, the United States National Academy of Sciences, and the American Philosophical Society. In 2004, he signed a letter along with 47 other Nobel laureates endorsing John Kerry for President of the United States as someone who would "restore science to its appropriate place in government".

His first wife, Elinor, died in 1983, after which he married Ellie Welch of Brookline, Massachusetts. Ramsey died on November 4, 2011. He was survived by his wife Ellie, his four daughters from his first marriage, and his stepdaughter and stepson from his second marriage.