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Space Topics: Search for Extraterrestrial IntelligenceThe Search for Extraterrestrial Intelligence: A Short HistoryPart 1: A Signal from the Stars It was the summer of 1967 and Jocelyn Bell, research student in radio astronomy at Cambridge, was having a bad day. As part of her doctoral dissertation she was monitoring a new radio telescope, scanning the skies for signs of interplanetary scintillation and quasars. But while the research was going well, some unexplained "scruff" kept appearing in her charts. At first, Bell and her advisor, Tony Hewish, thought that the signal must be some sort of Earthly radio interference. Such disturbances are normal in radio astronomy. But try as they might, Bell and Hewish could not eliminate the signal. It was coming from somewhere in the galaxy. Upon closer analysis they found something even more remarkable about the signal: it pulsated at precise regular intervals, 3 and 2/3 of a second apart. What natural radio source in the galaxy would send a signal with such accuracy and precision? In 1967 nobody knew, and the researchers began to suspect that possibly the source wasn't natural at all. Could it be that they were receiving a transmission from an alien civilization? Only half jokingly they began referring to the source as "LGM," standing for "little green men."
As word of the discovery spread, more and more astronomers began converging on the Cambridge observatory. To satisfy the growing interest, Jocelyn Bell had to spend more and more of her time tracking the strange signal and looking for others like it. She was not pleased: "Here was I" she recalls thinking, "trying to get a Ph.D. out of a new technique, and some silly lot of little green men had to choose my aerial and my frequency to communicate with us!" The LGM signal turned out to have nothing to do with alien civilizations. Within a year several similarly pulsating objects were detected. Their source, it was widely acknowledged, was rapidly spinning neutron stars, which were appropriately designated "pulsars." Radioactive neutron stars are very unpromising places to search for intelligent life. Nevertheless, it is not altogether surprising that for a while, Bell and Hewish seriously considered the possibility that their signal was a transmission from an alien world. The 1960s, after all, were the height of the "Space Age." Only a decade removed from the Sputnik, astronauts and cosmonauts were breaking new paths in space, each trying to outdo the other. Unmanned missions were being launched to the planets, and the race for the moon was about to reach its climax. The popular imagination was saturated with space exploration, with television series like "Star Trek" and " Lost in Space" dominating the airwaves. Is it surprising that radio astronomers came to wonder whether the signals they were detecting originated with otherworldly intelligence? Most significantly, perhaps, the search for alien civilizations was becoming scientifically respectable. Thanks to a small but growing cadre of scientists and engineers devoted to searching the skies for an alien signal, talk of advanced civilizations on other worlds was no longer reserved to science fiction buffs. The Search for Extra-Terrestrial Intelligence (SETI) was turning into a legitimate scientific enterprise, utilizing the most advanced technologies available and supported by some of the leading astronomers in the world. When Bell and Hewish considered the source of their signal, they did not need to look far: in their very field of radio astronomy, SETI was a significant and growing presence. It would have been surprising if they hadn't wondered whether they had accidentally stumbled upon the alien signal their colleagues were so ardently searching for. How did this transformation come about? How did the stuff of science fiction become the subject of real "hard" science? --Amir Alexander |
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