Charles Hard Townes, a professor emeritus of physics at the University of California, Berkeley, who shared the 1964 Nobel Prize in Physics for invention of the laser and subsequently pioneered the use of lasers in astronomy, died early Tuesday, 27 January, in Oakland, California (US). He was 99.
Until last year, Townes visited the campus daily, working either in his office in the physics department or at the Space Sciences Laboratory.
Townes was 35 in the spring of 1951 when, seated on a park bench among blooming azaleas in Washington, D.C., he was struck by the solution to a longstanding problem, how to create a pure beam of short-wavelength, high-frequency light.
That revelation – not much different from a religious revelation, Townes believed – eventually led to the first laser, a now ubiquitous device common in medicine, telecommunication, entertainment and science.
Then a professor at Columbia University and a consultant for Bell Telephone Laboratories, Townes had transitioned from working on radar during World War II to using shorter wavelengths of light to study the energy states of molecules, a field called spectroscopy. The problem bedeviling him was how to create an intense beam of microwave energy to use as a probe. Albert Einstein proposed in 1917 that the right wavelength of light can stimulate an excited atom to emit light of the same wavelength, essentially amplifying it, but Townes was stymied by how to corral a gas of excited atoms without them flying apart.
His revelatory solution allowed him to separate excited from non-excited molecules and store them in a resonant cavity, so that when a microwave traveled through the gas, the molecules were stimulated to emit microwaves in step with one another: a coherent burst. He and his students built such a device using ammonia gas in 1954 and dubbed it a maser, for microwave amplification by stimulated emission of radiation.
Four years later, in 1958, he and his brother-in-law and future Nobelist Arthur Schawlow conceived the idea of doing the same thing with optical light, but using mirrors at the ends of a gas tube to amplify the light to get an “optical maser.” Bell Labs patented the laser, while Townes retained the patent on the maser, which he turned over to a nonprofit. Townes’ appointment as director of research for the U.S. government’s Institute of Defense Analysis in 1959 slowed his efforts to build an optical device, opening the door for Theodore Maiman to demonstrate the first laser – light amplification by stimulated emission of radiation – in 1960.
Townes shared the 1964 Nobel Prize in Physics with two Russians, Aleksandr M. Prokhorov and Nicolai G. Basov, who independently came up with the idea for a maser.
To date, more than a dozen Nobel Prizes have been awarded for work done with lasers. Lasers are incorporated into consumer electronics and optical fibers, surveying equipment and printers, light shows and laser pointers. Lasers are used to cut metal, slice through tissue during surgery, trap atoms, and even initiate nuclear fusion.
Townes himself went on to use masers for radio astronomy, and lasers for infrared astronomy and interferometry, and promoted their use in areas as diverse as precision timekeeping – the atomic clock – and extraterrestrial communication. With the help of lasers, he and colleagues detected the first complex molecules in interstellar space and first measured the mass of the black hole in the center of our galaxy.
He also served on numerous government panels. From 1964 to 1970, at a time when many scientists questioned the value of a manned space program, Townes accepted an appointment as chairman of an ad hoc science advisory committee to NASA’s manned space program, to secure support for the Apollo moon flights from the larger scientific community and ensure that they would yield maximum benefits in scientific research. In 1981 he chaired a panel reviewing President Ronald Reagan’s planned deployment of MX missiles, and he actively advocated controls on nuclear weapons, including a test ban treaty to regulate underground weapons testing.
As with the maser, “he pursued the infrared interferometer because he saw a new technique with great possibilities,” said Ed Wishnow, who collaborated with Townes beginning in 2007. “He really had a great sense of what was possible and reasonable; he was farsighted, yet grounded at the same time.”
“Science tries to understand what our universe is like and how it works, including us humans,” he wrote. “Religion is aimed at understanding the purpose and meaning of our universe, including our own lives. If the universe has a purpose or meaning, this must be reflected in its structure and functioning, and hence in science.”
Townes was a member of the National Academy of Sciences, National Inventors Hall of Fame, South Carolina Hall of Fame and Engineering and Science Hall of Fame. He received honorary degrees from 25 colleges and universities and numerous honors, including the National Medal of Science, National Academy of Sciences’ Comstock Prize and the John J. Carty Medal, Rumford Premium of the American Academy of Arts and Sciences, Stuart Ballentine Medal of the Franklin Institute (twice), the C.E.K. Mees Medal of the Optical Society of America, the Medal of Honor of the Institute of Electrical and Electronics Engineers, Plyler Prize of the American Physical Society, NASA’s Distinguished Public Service Medal, Thomas Young Medal and Prize of the Institute of Physics and the Physical Society (England), Wilhelm Exner Award (Austria) and the 1979 Niels Bohr International Gold Medal.
He also was a member and former president of the American Physical Society, a member of the American Academy of Arts and Sciences and the National Academy of Engineering, and a foreign member of the Royal Society and the Russian Academy of Sciences. A member of the American Astronomical Society, in 1998 he was awarded the society’s Henry Norris Russell Lectureship for a lifetime of eminence in astronomical research.
Townes is survived by his wife, Frances Hildreth Townes (nee Brown), whom he married in 1941; daughters Holly Townes, Linda Rosenwein, Ellen Townes-Anderson and Carla Kessler; six grandchildren and two great grandchildren.