As a young man, Dr. Glauber worked at Los Alamos National Laboratory, where the atomic bomb was built. He was one of the last survivors among the scientists who saw the first bomb test in the New Mexico desert in 1945.

A longtime member of the physics faculty at Harvard University and an adjunct professor of optical sciences at the University of Arizona in Tucson, Dr. Glauber conducted work that provided a quantum explanation for the interaction between light and matter.

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In 2005, Dr. Glauber was awarded half of the Nobel Prize in physics for what the Nobel Committee described as “his contribution to the quantum theory of optical coherence.” The other half was awarded to John L. Hall and Theodor W. Hänsch for their work in precision spectroscopy.

Optical coherence is a term associated with the pure beams of light produced by lasers, and it was the development of lasers that helped prompt Dr. Glauber to develop his theory.

In part, it provides a fundamental way of explaining and distinguishing between the “coherence” of the narrow, tightly focused laser beam, characterized by its single frequency, and the light that is produced by everyday sources, which generally contain many frequencies. Sunlight, or light from an electric bulb, is divergent and is termed “incoherent.”

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Modern physics is based to a great extent on quantum theory, in which matter and energy may exist as both wave and particle. Even before quantum theory, it was recognized that light had aspects of both. But the theory provides more powerful and sophisticated explanations of that duality and of how it affects the physical world.

In the modern explanation, particles of light, known as photons, follow circumscribed laws. Quantum accounts of photons and their interactions depart from the predictability and continuity that typify earlier physics.

In the case of light, the theory involved is known as quantum electrodynamics. Light waves are a form of electromagnetic radiation, and quantum electrodynamics unites the quantum theory with electromagnetism.

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Calling him “Dr. Quantum Optics,” University of Rochester physicist Joseph H. Eberly described Dr. Glauber as “the signifier for an entire field.” Dr. Glauber “was a principal architect and builder” of quantum optics. Eberly added that Dr. Glauber was also “a passionate long-term guardian.”

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In addition to his work in quantum optics, Dr. Glauber was known for contributions to high-energy physics and statistical physics, and he had a reputation as a witty and humorous storyteller. In his Nobel lecture, he suggested a modern version of one of the early sentences of the Bible, “Let there be light.”

In Dr. Glauber’s formulation, “the good Lord said, ‘Let there be quantum electrodynamics.’ ”

Roy Jay Glauber was born in New York on Sept. 1, 1925. His mother was a homemaker trained as an elementary school teacher, and much of his early childhood was spent on the road with her and his father, a traveling salesman.

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As a child, he built model airplanes and spent days constructing a reflecting telescope. A spectroscope he built as a teenager helped him win two science fair prizes, and he was one of the first students to attend the newly opened Bronx High School of Science, which counts eight Nobel winners among its graduates.

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With the aid of a scholarship, he enrolled at Harvard in the fall of 1941; having skipped two grades at public school, he was two years younger than most of his classmates. Instruction was accelerated by the demands of World War II, and by the time he was 18 he had largely acquired the equivalent of a graduate school education.

Recruited for the Manhattan Project in 1943, he soon found himself absorbed in making calculations connected to determining the behavior of neutrons and the amount of nuclear fuel necessary to ensure an atomic explosion.

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In 1946 he returned to Harvard, completed his undergraduate studies and entered graduate school, where future Nobel Prize winner Julian Schwinger was his thesis adviser. After receiving his doctorate in 1949, Dr. Glauber spent time at the Institute for Advanced Study in Princeton, N.J, led by J. Robert Oppenheimer, one of the architects of the atomic bomb.

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He returned to Harvard in 1952 and began scaling the academic ladder at a time in which the laser was being developed, which led him to raise questions about the quantum behavior of the laser’s output. Dr. Glauber’s seminal work was published in 1963.

His marriage to Cynthia Rich ended in divorce. They had two children. A complete list of survivors was not immediately available.

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