Are We Alone in the Universe? (On Science Friday

by JOEL N. SHURKIN

According to one account, a small group of physicists at the University of Chicago were having lunch one day in 1950 with physicist Enrico Fermi, joking about the many newspaper articles reporting visits from UFOs. In one story a group of neighborhood kids had apparently stolen garbage can lids and tossed them like Frisbees in front of people’s windows. Neighbors thought the whizzing disks were otherworldly visitors.
 
Fermi, known to colleagues as “The Pope” because he seemed infallible, sat quietly for a few seconds while the laughter subsided and then asked, “Where is everybody?” He meant extraterrestrials.
Given the vastness of the cosmos, it seems incredible that Earthlings could be the first technological society. Assuming that intelligent life on other planets is common, Fermi supposed that the time any ambitious society would need to colonize the galaxy was a mere tens of millions of years—a small fraction of the much older Milky Way’s age. So, colonization should have happened by now. But we don’t see any evidence, such as feats of astroengineering, for example. “This struck Fermi as an interesting conundrum,” writes Seth Shostak, a senior astronomer at the SETI (Search for Extraterrestrial Intelligence) Institute, in an email. The quandary became known as Fermi’s Paradox.

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