Maser and laser inventor Charles Townes died yesterday at age 99, after a nearly 80-year career. University of California at Berkeley professors reported that the Nobel Prize and IEEE Medal of Honor winner was still working in his office or laboratory daily as recently as last year. Colleagues called him “one of the most important experimental physicists of the last century” and say his passing marks the end of an era.
I interviewed Townes in 1991 when he was 76, an age at which many would have at least contemplated retirement, but not only was he still as busy as ever, working six days a week and often into the evening, he had just moved into a new area of research—using infrared spatial interferometry for astronomy. “It is a tough thing to do, but I think quite important,” he told me at the time. “In the long run it could open up a very exciting field.” It did indeed, and he published papers on the subject, built a laser interferometer for the Mt. Wilson observatory, and advanced the field for decades.
Townes also told me that throughout his career he kept burnout at bay by taking a complete break once a week—he never even let a thought about physics into his head on Sundays (good advice for any of us). Here’s what else he told me about discovering the maser and laser and the importance of changing research topics before becoming stale.
[The following was first published in "Innovative Genius," a special report in IEEE Spectrum, December 1991]
In just 15 minutes in the spring of 1951, Charles Townes created the basic design for the maser. He scribbled his calculations on a scrap of paper, and put the scrap in his pocket, all the while sitting on a park bench in Washington, D.C., admiring a garden of azaleas. (He was slower inventing the laser, whose gestation lasted nine months.)
Townes was sure his maser design would work—he had spent five years struggling with ideas for producing extremely short radio waves for spectroscopic use. But outstanding scientists initially insisted his theory was wrong, he said, including Niels Bohr and John von Neumann. A few colleagues misinterpreted the application of the uncertainty principle; others simply doubted the scheme’s technical feasibility.
Such opposition might have stalled a less confident researcher but Townes said, “I didn’t find it upsetting at all.” On another occasion he remarked, “I don’t mind people telling me that I’m wrong. I have to try to examine for myself what is right.”
The implementation of the maser would not be easy, he did grant that. It was fall before he, as a professor at Columbia University, New York City, finally found a graduate student he thought could handle it and was interested in the gamble—James Gordon. Later, a bright young postdoctoral fellow, Herbert Zeiger, joined the project. Even then, after 2 ½ years of work, he recalled, the past and present physics department chairmen came to his office and said, in effect, “Look, you know this isn’t going to work, both of us know it’s not going to work, you’re wasting money and should stop.”
Townes disagreed, and the two left him alone (the job took three more months). The maser quickly found uses as a very precise oscillator and clock and also as an amplifier of microwaves more sensitive than any previously known.
“Disagreement is often important in the scientific process and calls for self-examination,” Townes told IEEE Spectrum, “but it doesn’t usually disturb me, although in a few cases I remember it being a nuisance.”
He credits his parents with his capacity for being comfortable with unpopular views. They had a strong religious orientation, he said, and were quite ready to adopt a different position from the rest of society. “They didn’t speak out against people who disagreed with them, but simply tried to consider what was right or wrong, and it was very clear that they expected us to be different when necessary,” he told us.
Townes’s work on the maser led to the laser—after a sabbatical in Europe and Japan and a few years researching the ammonia beam and solid-state masers. With masers operating in the 1-2-cm wavelength region, Townes wanted a device that would generate still shorter waves.
For some time in the mid-1950s, he waited for inspiration, but when it did not strike again, he decided to sweat out a reasonable way to reach his goal. After wrestling with the pertinent equations, he realized that it would be practical to abandon the pursuit of incrementally shorter wavelengths in favor of much shorter wavelengths—even the visible light range—where much more was already known.
About nine months’ work with his brother-on-law, Arthur Schawlow, a Bell Laboratories researcher, completed the theory and design for the laser. Townes then started lab work with a student, but bowed out upon being appointed director of research for the Institute for Defense Analyses in Washington, D.C., a position he felt conscience-bound to accept. Townes received a 1964 Nobel Prize for his efforts and Schawlow a 1981 Nobel for closely associated work.
The maser and laser were by no means the sole focus of Townes’s career. In fact, he has been loath to stay in any specialty for long. “Once a field is well established, I don’t feel the need to do it any more,” he told Spectrum. “It’s just not as interesting to me to run with a crowd. It’s more useful and much more fun to open up a new field.”
This was a trait of his from childhood on. His earliest scientific interest was natural history. As children in Greenville, S.C., he and his older brother would catch insects and animals and collect leaves and rocks, classifying and displaying them carefully. But while he thought about studying biology in college, his brother “was so good at it I decided I shouldn’t try to compete.”
Anyway, as a 16-year-old freshman at Furman University in Greenville, S.C., he discovered mathematics and, net year, physics. Though he made the latter his specialty, because it had more to do with the real world than mathematics, physics was not a standard major at Furman, and by his last year Townes was teaching himself from a textbook. As a graduate student, he became involved in nuclear physics at Duke University, Durham, N.C., in 1936 and then at the California Institute of Technology in Pasadena until 1939. For his graduate thesis, he measured the spins of atomic nuclei. He had hoped for a postdoctoral fellowship at a top university, but Bell Laboratories made him his only offer.
Accepting, for a year he dipped into basic research areas before being assigned to radar navigation and bombing system design for the war effort. It was this work that suggested to him that microwaves could be used for high-resolution spectroscopy—a wholly novel idea that he began exploring in 1946, publishing papers and receiving several patents on the use of molecules for electronics.
His move from Bell Labs to Columbia University in 1948 did not affect his research. “I finally closed the book on microwave spectroscopy in 1955 by writing a book on it, “ Townes punned to us. “We had explored most of the physics, the field had developed and it was time for me to move on and do something else.”
The something else was masers and lasers, interrupted by the two-year stint in Washington. Next Townes moved on to the Massachusetts Institute of Technology (MIT) in Cambridge. He did some research, but as provost was mainly an administrator.
Meanwhile, lasers had become a hot subject, one he felt no longer needed him, though he was impressed by the rate of their development. “I knew from the beginning that it was going to be important, because it married the fields of optics and electronics,” he said, “though some people kidded me that the laser was an idea looking for an application.”
In short, it was time for another change—to radio and infrared astronomy. At several other points Townes had eyed the field, but more pressing interests had intervened. “I felt that astronomers were missing good bets by neglecting to look for stable molecules in interstellar regions and in not fully using new technologies to work in the infrared and microwave regions,” he told Spectrum.
He had in fact predicted the molecules’ existence in a 1955 paper written during his sabbatical. But apart from his brief studies then, he knew little about astronomy. So stepping down as an administrator at MIT, he spent a year studying the subject, largely at neighboring Harvard. Then in 1967 he moved to the University of California at Berkeley, to teach physics and begin what became an extensive program of experimental research in astronomy.
One of his first efforts was to look for those stable molecules in space. With other colleagues at Berkeley he found ammonia and then water, which, to his surprise and delight, was producing powerful natural masers in space. This work demonstrated for the first time the presence of dense molecular clouds—another field Townes left when it rapidly turned popular.
He turned to mid- and far-infrared spectroscopy, particularly of the galactic center. There measurements by Townes and colleagues have shown the presence of a very massive object, presumably a black hole. Most recently he has switched to infrared spatial interferometry with the goal of obtaining angular resolution on astronomical objects one or two orders of magnitude higher than has been previously possible at infrared wavelengths. “It is a tough thing to do, but I think quite important,” Townes said. “In the long run it could open up a very exciting field.”
All these changes of direction have kept Townes fresh despite long hours. (He works many nights and most Saturdays.) He finds it stimulating, too, to exchange ideas with other researchers. He developed the maser, for example, he said, in a laboratory where others were working on molecular beams. Also, several weeks before his sudden insight, he had heard a German researcher give a talk on high-intensity molecular beams, and he had recently read a seemingly unrelated paper on negative temperatures.
He has held burnout at bay, Townes believes, with rule he has kept through his career: he does not even think about physics on Sundays. “Whenever I start, I tell myself, wait a minute, worry about that tomorrow,’” Townes said. “Taking a complete break like that keeps me refreshed.” During those hours, he dabbles in a variety of hobbies, from hiking to scuba diving, none of which, he said, he takes seriously.
“Physics,” admits the 76-year-old scientist, “is my only permanent hobby.”
For more about Townes, including audio clips of interviews, check out the IEEE Global History Network’s oral history.
