In 1951, physicist Charles Townes was lost in thought on a park bench in Washington, D.C., pondering a years-long puzzle: how to create an intense beam of light – short in wavelength and high in frequency – with far-reaching practical uses. Albert Einstein had theorized that it could be done, but no one had yet managed the feat.
On that bench, surrounded by blooming azaleas, the solution came to Townes, then a 35-year-old Columbia University researcher. It involved a flash of bright light, a population of excited ammonia molecules and a mechanism for limiting the wavelengths they could then emit.
On the back of an old envelope, he “just scratched it out,” he said of his brainstorm.
A few years later, he and two colleagues had designed and built a device they called a maser, with the “m” signifying microwave energy.
When the microwaves were replaced by light waves, the laser was born.
Townes, whose invention brought him the 1964 Nobel Prize in physics and spawned advances in nearly every area of modern society – including home entertainment technology, medicine, cosmology and commerce – died Tuesday in Oakland while on his way to a hospital, according to UC Berkeley, where he spent the last five decades of his career. He was 99.
“He was one of the most important experimental physicists of the last century,” UC Berkeley astrophysicist Reinhard Genzel said in a statement. “His strength was his curiosity and his unshakeable optimism, based on his deep Christian spirituality.”
Townes once said he regarded his “revelation” on the park bench as a sign of the interplay between spiritual belief and scientific inquiry. In 2005, he received the prestigious Templeton Prize for Progress Toward Research or Discoveries about Spiritual Realities.
Few other modern inventions have had the wide-ranging effect of the laser. Lasers are at the core of the CD and DVD players in the home, the bar-code scanner in the supermarket, range-finders and altimeters used by the military, speed detectors used by state troopers and a host of other commercial products.
In medicine, their uses include laser scalpels, smoothing the skin, removing tattoos, reattaching retinas and shaping the cornea to eliminate the need for glasses. In astronomy, they are used for measuring distances and examining cosmological phenomena in deep space. In industry and government, they are used for high-speed transmission of data over fiber-optic cables.
More than a dozen Nobel Prizes have relied on work done with lasers.
Physicist Theodor W. Hänsch of Germany’s Max Planck Institute for Quantum Optics, upon learning that he would receive a Nobel for using lasers to study the properties of atoms and molecules, said, “We all together stand on the shoulders of our giant, Charlie Townes.”
The technology has become so common that the term laser, an acronym for “light amplification by the stimulated emission of radiation” coined by Townes and his students, has become generally understood throughout society – even though few understand the principles behind it.
The idea of stimulated emission of radiation at the heart of the laser was put forth by Einstein in 1917. He reasoned that the absorption of radiation of a particular wavelength by atoms would stimulate them to emit radiation of the same wavelength.
Townes’ essential contribution was to identify and create conditions in which large numbers of atoms were in an unstable state in which they would emit more energy than they absorbed.
Microwaves can have wavelengths as long as a few feet, but Townes was working with wavelengths of about half an inch and seeking still shorter ones, which would have more uses. But electronic devices that might generate such short wavelengths were too small to produce sufficient power for any foreseeable application.
Townes reasoned that developing electronic amplifiers would not work and started to imagine using molecules, which produce radiation when they vibrate at high speeds.
Back at Columbia, his colleagues were skeptical and urged him to abandon the project. But he and physicist Arthur Schawlow, a collaborator and friend who later became his brother-in-law, forged ahead. They built the first maser in 1954.
The pair used the same concepts to design a device that would emit light at frequencies one-100,000th as short as microwaves. They published their design in the December 1958 issue of the journal Physical Review and obtained a patent in 1959.
Other scientists fell on this new idea avidly. In 1960, Theodore Maiman of the Hughes Research Institute in Malibu built the first working laser, largely based on the Townes-Schawlow design.
Townes shared the Nobel Prize in 1964 with Nicolay Gennadiyevich Basov and Aleksandr Mikhailovich Prokhorov of the Soviet Union, who also made significant contributions to the development of the maser and laser.
The invention of the laser was also claimed by Gordon Gould. As a Columbia University graduate student he drew up a design for the laser on his own in 1957 but did not file for a patent until 1959.
This Los Angeles Times story was written by The Sacramento Bee’s Charles Piller when he worked there. Thomas H. Maugh II contributed.