Norman Foster Ramsey, Timekeeper of the Atom


In the autobiography that he wrote on the occasion of obtaining the Nobel Prize, he acknowledged that his initial interest in science was stimulated by reading an article on the quantum theory of the atom, but that at that time he did not imagine that physics could reach be a profession; a profession that he exercised step by step. He initially obtained his degree in Mathematics at Columbia University in New York and later, helped by this university, he moved to Cambridge (United Kingdom), where he obtained a second degree, this time in Physics. In England he had the opportunity to work at the Cavendish Laboratory, where he met many of the promoters of atomic physics.

Norman Foster Ramsey Jr. (Washington, 1915), who died on November 4 at the age of 96, was awarded the Nobel Prize in Physics in 1989 for the invention of the method of separate oscillatory fields, thanks to which the development of the atomic clock was feasible . Ramsey's work currently benefits from devices as heterogeneous as GPS navigation systems, radio telescopes or magnetic resonance diagnostic devices. Ramsey shared the award with Hans Dehmelt and Wolfgang Paul.

Back in Columbia, he began his doctoral thesis under the supervision of Isidor Rabi (Nobel Prize in Physics in 1944), who in 1937 was a pioneer in developing a method for measuring the magnetic properties of atomic nuclei. That time was extremely important for the progress of all nuclear technology, but in the case of Rabi's experiment, as in many others aimed at measuring very short times, his discoveries transcended the nuclear field and served as the basis for the important development that Atomic and molecular physics has experimented since the 1970s.

Rabi himself applied his magnetic resonance technique to the study of atomic structure and its characteristic frequencies, but it was Ramsey who made a decisive contribution to its practical application. He introduced an improvement based on the use of two separate fields that induce atomic oscillations in two different regions that, by interfering with each other, provide a very high resolution image. In other words, the application of these external fields allows us to clearly read the oscillation frequencies of atoms and transform them into images or precise witnesses of the passage of time.

Ramsey devoted the last years of his scientific career, until his retirement in 1986, to Harvard University. The two most important technological applications based on his discoveries are nuclear magnetic resonance and the atomic clock. The former has become a medical diagnostic technique of the first magnitude, whose application is nowadays common in traumatology, but which, in combination with other tomography, is providing images of brain dynamics that promise important advances in the early detection of degenerative diseases of the brain. brain; the second led to the development of the cesium atomic clock, which in 1967 was adopted as a time measurement standard.

Although the image of a scientist obsessed with discovering the essential properties of matter and their practical applications perfectly defines Ramsey's personality, his biography has a lesser-known extra-scientific aspect: his courageous confrontation with Senator McCarthy's witch hunt during the years fifty. Ramsey was one of the few prominent investigators to testify on behalf of several colleagues accused of communism. "All of that was against people's rights," he declared.