Laser inventor Charles Hard Townes, professor emeritus of physics at the University of California, Berkeley, turns 99 on July 28, and an adoring campus is throwing him a long-overdue birthday party.
Only now nearing retirement – he plans to shutter his physics department office this summer, but will continue to make daily visits to his office at UC Berkeley’s Space Sciences Laboratory – Townes’ career highlights include a 1964 Nobel Prize in Physics for discovering the laser, ground-breaking astronomical research, wide-ranging admiration for his efforts to reconcile science and religion, 31 honorary degrees and 38 awards.
Townes and his wife, Frances, will attend the 2 p.m. birthday party on Monday, July 28, though Townes now needs a wheelchair and oxygen to get around campus. His birthplace, the city of Greenville, S.C., and his current home town, Berkeley, Calif., have issued proclamations declaring the day “Charles H. Townes Day.”
“Charles Townes embodies the best of Berkeley; he’s a great teacher, great researcher and great public servant,” said UC Berkeley Chancellor Nicholas Dirks. “As we celebrate this 99-year milestone and a career spanning nearly 80 years, we can only be impressed by the range of his intellectual curiosity, his persistence and his pioneering spirit.”
“Berkeley is quite open minded, it lets you do what you want to do,” Townes said in a recent interview. “It’s a great place to do interesting things and a great university. I have a good time doing physics; it’s not work, it’s just fun.”
Revelation
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 long standing problem, how to create an pure beam of short-wavelength, high-frequency light.
That revelation – not much different from a religious revelation, Townes believes – eventually led to the first laser, a now ubiquitous device common in medicine, telecommunication, entertainment and science.
Credit: Elena Zhukova
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.
From maser to laser
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 non-profit. 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 rival 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 ad 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 time keeping – 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.
“As soon as he believes that the biggest, most fundamental and difficult questions in a field are answered, he leaves the tidying up to other people and goes somewhere else to search for answers,” said Walt Fitelson, who has worked with Townes for more than 40 years. “He is an amazing scientist, amazing educator, and amazing human being.”
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.
Southern born
Born in 1915, Townes attended Furman University in Greenville, graduating 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.
Nevertheless, Townes continued this work after accepting a faculty position at Columbia University in 1948, where he built the maser with graduate student James Gordon and post-doctoral researcher Herbert Zeiger. In 1961, after a brief tenure at the Institute for Defense Analyses, he was appointed provost and professor at MIT. He continued his research on quantum electronics and moved into the new field of infrared astronomy. In 1967 he was named a UC Professor-at-large based on the UC Berkeley campus.
“He came to Berkeley because it gave him the opportunity that almost no one else would, to look for complex, polyatomic molecules in space, which most people didn’t believe were there,” Fitelson said.
Newly arrived at UC Berkeley, Townes soon learned of plans by young professor William “Jack” Welch to build a short-wavelength radio telescope, and offered some of his start-up funds to build a maser amplifier and microwave spectrometer so the telescope could be used to search for evidence of complex molecules, like ammonia, in space. Told by many, including the astronomy department chairman, that such molecules could not possibly survive in space, Welch and Townes persisted and in 1968 proved them wrong. They were the first to discover three-atom combinations – ammonia and water vapor – near the center of the Milky Way Galaxy. Others soon discovered even more complex molecules, providing evidence for a host of chemical reactions taking place in young and dying stars and giving credence to the idea that molecules from space could have seeded Earth with the building blocks of life.
“This was my first foray into astronomy, and the discovery was a big boost for me,” Welch said. “And it was all his idea. Charlie is just a terrific guy.”
Welch and Townes went on to discover the water maser in space.
First evidence for black hole at center of Milky Way
In a UC Berkeley lab staffed mostly by students, Townes moved on again to pioneer the field of infrared astronomy, essentially looking at sources of heat in outer space, and precision infrared spectroscopy. He developed a novel infrared detector incorporating a precision CO2 laser, which made it easier to study this wavelength of light without contamination from hot sources all around us. His infrared studies of the center of the galaxy with Reinhard Genzel, now professor of physics at UC Berkeley and director of the Max Planck Institute for Extraterrestrial Physics, revealed in 1985 swirling gas clouds that could only be orbiting a massive object, presumably a black hole. That discovery was later confirmed by Genzel and others.
Credit: Taran Singh
Townes subsequently built an interferometer, again using lasers, that combined infrared light collected by three separate telescopes into high-resolution images normally obtainable only with a much larger telescope. This Infrared Spatial Interferometer Array, housed in movable trailers at the Mt. Wilson observatory outside Los Angeles, can measure the diameters of stars that appear only as points of light in most telescopes. He and his colleagues have conducted long-term studies of the dust disks around old stars and the changes in aged red giants such as Betelgeuse, and are preparing the telescopes to look for possible infrared laser signals from newly discovered planets circling nearby stars, in search of extraterrestrial civilizations.
As with the maser, “he pursued the infrared interferometer because he saw a new technique with great possibilities,” said Ed Wishnow, who has collaborated with Townes since 2007. “He really has a great sense of what is possible and reasonable; he is farsighted, yet grounded at the same time.”
“Charlie has created an incredible legacy here at Berkeley, and his accomplishments have direct impact on many different fields in the physics department,” said physics chairman Steven Boggs. “We have been fortunate to have had the privilege of his wisdom and insight for so much of his long and prestigious career.”
Throughout his life, Townes maintained an interest in the intersection of science and religion. His seminal 1966 article, “The Convergence of Science and Religion,” established him as a unique voice — among scientists, in particular — seeking commonality between the two disciplines.
“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, which is awarded for contributions to “affirming life’s spiritual dimension.”
“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 married Frances Brown In 1941, and they raised four daughters.
What’s Townes’s secret to a long life? “Good luck is one, but also just having a good time,” he told an interviewer in 2005. “I’d say the secret has been being able to do things that I like, and keeping active.”
