4273-05
Reflections on Forty Years
of Optical SETI --
Looking Forward and Looking Backward
by
Charles H. Townes

Picture by Tom McDonough, The Planetary Society, 1993
Abstract
When, in early 1961, interstellar communication with lasers was first discussed, it was met with interest but not enthusiasm. The scientific community was thinking of laser powers in the kilowatt range (which had not yet been actually achieved) and telescopes of maximum diameter 200 inches. Now there are lasers of average power 106 watts, pulsed power 1015 watts, and telescopes of diameter 10 meters. Just what technology an advanced extrasolar civilization would have is still debatable, but on earth communication with lasers is growing rapidly and now "Optical SETI" seems to many a likely prospect. In addition to increased power and variety of lasers, with expectation of further growth, the easy use of short pulses alleviates the need for high spectral resolution required by CW laser communication, and gives high signal to noise ratios. Such changes in our own technology and views over only a few decades obviously stimulate open-mindedness about the state of technical developments and communication in any external civilization. And what are the resulting speculations?
Keywords
Optical SETI, 1961, lasers, communications, technology, history.
Principal Author Biography
| 1915 | Born in Greenville, S.C. |
| 1935 | Receives a B.A. and a B.S. from Furman University. |
| 1937 | Receives an M.A. from Duke University. |
| 1939 | Joins Bell Labs on West Street, N.Y.C., after receiving his Ph.D. degree in physics from the California Institute of Technology. |
| 1948 | Becomes an associate professor of physics at Columbia University. |
| 1949 | Meets Arthur L. Schawlow, who comes to Columbia University on a fellowship and works as a research assistant to him. |
| 1950 | Becomes a professor of physics at Columbia and executive director of the Columbia Radiation Laboratory. |
| 1951 | Conceives if the idea of a maser (similar ideas occur independently to A. Prokhorov and N. Basov in Moscow and J. Weber of the University of Maryland). |
| 1952 | Becomes chairman of Columbia's Physics Department. |
| 1953 | Builds the first maser with J. P. Gordon and H. J. Zeiger at Columbia. |
| 1955 | Co-authors the book Microwave Spectroscopy with Schawlow. |
| 1956 | Serves as a Bell Labs consultant in the field of solid-state masers. |
| 1957 | While serving as a consultant to Bell Labs, begins working with Schawlow on the principles of a device -- the laser -- that could operate at wavelengths a thousand times shorter than the maser. |
| 1958 | Proposes with Schawlow in a paper published in the December Physical Review that the principles of the maser could be extended to the optical regions of the spectrum using an incoherent pump source. |
| 1959-61 | Becomes vice-president and director of research for the Institute for Defense Analysis in Washington, D.C. |
| 1960 | Receives with Schawlow a patent for the invention of the laser. The first working laser is built by Theodore Maiman at Hughes Aircraft Company using ruby at 0.69 microns. |
| 1961 | Co-authors paper with R. N. Schwartz titled: "Interstellar and Interplanetary Communication by Optical Masers" an April issue of Nature. This is the first description of the optical approach to SETI. |
| 1964 | Shares the Nobel Prize in Physics with A. Prokhorov and N. Basov of the Lebedev Institute in Moscow for "fundamental work in the field of quantum electronics which has led to the construction of oscillators and amplifiers based on the maser-laser principle." |
| 1966 | Becomes Institute Professor at MIT. |
| 1967 | Becomes University Professor of Physics at the University of California at Berkeley. |
| 1986 | Becomes University Professor of Physics, Emeritus, at the University of California at Berkeley. |
| 1993 | Participated in SPIE's OSETI I Conference. |
| 2001 | Will participates in SPIE's OSETI III Conference which marks the 40th anniversary of Optical SETI. |
Principal Author Affiliation
Space Sciences Laboratory
University of California,
Berkeley, CA 94720-7450
USA
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Email: cht@isi16.ssl.berkeley.edu
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