Charles Hard Townes, one of the giants of modern physics and inventor of the laser, died early Tuesday, January 27. A professor emeritus of physics at the University of California, Berkeley, he was 99 and in failing health. He shared the 1964 Nobel Prize in Physics for inventing the laser and subsequently pioneered the use of lasers in astronomy. Until last year, Townes visited the Berkeley campus daily, working either in his office in the physics department or at the Space Sciences Laboratory.
Townes was born on July 28, 1915, in Greenville, SC, attended Furman University, and graduated summa cum laude in 1935 at the age of 19 with a BS in physics and a BA in modern languages. He was a member of the swim team, the football band, and the college paper. He completed an MA in physics at Duke University in 1936 and moved to Caltech, from which he obtained his Ph.D. in 1939. His thesis involved isotope separation and nuclear spins.
He immediately joined the technical staff at Bell Labs in New Jersey, where he stayed through the war designing radar bombing systems. He then began applying his expertise in microwaves to spectroscopy, which he foresaw as providing powerful new tools for probing the structure of atoms and molecules and for controlling light. Bell Labs eventually terminated the program, however, seeing little application for it.
At age 35, in the spring of 1951, Townes was seated on a park bench among blooming azaleas in Washington, D.C., when he was struck by the solution to a longstanding problem: how to create a pure beam of short-wavelength, high-frequency light. That revelation eventually led to the first laser.
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 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.
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 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 the Milky Way galaxy.
He also served on numerous government panels. From 1966 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.
Townes, a longtime member of the First Congregational Church of Berkeley, often emphasized the importance of faith in his life. “My own view is that, while science and religion may seem different, they have many similarities, and should interact and enlighten each other,” Townes wrote in a statement upon accepting the 2005 Templeton Prize. “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 is survived by his wife, Frances Hildreth Townes, whom he married in 1941; daughters Holly Townes, Linda Rosenwein, Ellen Townes-Anderson and Carla Kessler; six grandchildren and two great grandchildren.
Source: UC Berkeley