Harold Francis Weaver, a pioneer of radio astronomy who discovered the first microwave laser, or maser, in space, passed away peacefully in his Kensington, California, home on April 26 at the age of 99.
Weaver was a professor emeritus of astronomy, the founder of UC Berkeley’s Radio Astronomy Laboratory and its director from 1958 until 1972 and a former chairman of the Department of Astronomy.
As a young astronomer at the University of California’s Lick Observatory near San Jose, and starting in 1951 as a member of the UC Berkeley astronomy faculty, Weaver became keenly aware of the potential of radio astronomy, which at the time was a young field. Many objects in space give off radio waves, from gas clouds and stars to galaxies, and today astronomers even observe microwave background radiation to infer the early history of the universe shortly after the Big Bang.
After several years of proposal writing, talking to administrators and searching for funds, Weaver founded the Radio Astronomy Laboratory in 1958. Two of his colleagues were Samuel Silver, a professor of electrical engineering and the namesake of the campus’s Space Sciences Laboratory, and Luis Alvarez, a physicist and winner of the 1968 Nobel Prize in Physics.
The lab dedicated its first telescopes, including an 85-foot dish – at the time, one of the world’s largest – in June 1962, in Hat Creek Valley in Northern California, far from radio noise that would have interfered with observations. Using the dish, Weaver and his colleagues discovered the first astrophysical maser – microwave amplification by stimulated emission or radiation, the radio equivalent of a laser – which had only been realized on Earth eight years earlier by the late UC Berkeley physicist and Nobel laureate Charles Townes.