Most of our experiments so far have used large radio antennas in an effort to eavesdrop on radio signals transmitted by other societies, an approach that was dramatized by Jodie Foster in the 1997 movie Contact. Unlike other alien potboilers, Contact’s portrayal of how we might search for extraterrestrials was reasonably accurate. Nonetheless, that film reinforced the common belief that SETI practitioners paw through cosmic static looking for unusual patterns, such as a string of prime numbers. The truth is simpler: We have been searching for narrow-band signals. “Narrow-band” means that a large fraction of the transmitter power is squeezed into a tiny part of the radio dial, making the transmission easier to find. This is analogous to the way a laser pointer, despite having only a few milliwatts of power, nonetheless looks bright because the energy is concentrated into a narrow wavelength range.
The search for alien artifacts continues, along with the search for signals:
The appealing thing about artifacts is that finding them is not time-critical. In contrast, to search for signals, you need to activate your instruments at the right time. It doesn’t help to look for radio pings, laser flashes, or neutrino bursts if E.T. reached out to touch us during the reign of the dinosaurs or will do so a hundred million years from now. Artifacts have no such synchronicity problem. That said, looking for artifacts has its own bummer factors. Anything beyond our solar system would need be truly huge to be visible; cousins of the starship Enterprise would be very difficult to find. More.
Question: Does the prediction mean they’ll stop looking in 2036? Or that any conclusions will be drawn if that date passes? We surmise no:
SETI is not a traditional science problem in which a hypothesis can be falsified. We can never prove that the aliens are not out there, only that they are. But our ability to search improves with every technological innovation. I compare the situation to the year 1491. European civilization had been around for 2,500 years, yet the Americas were not on any map. Mesoamerican civilization, for its part, had been around for about as long, but also was ignorant of what lay over the oceans. With a glimpse and a shout from a sailor on the Pinta, everything changed.
The analogy is flawed. The Europeans were not looking for the Americas; they ran into them while looking for China, which they knew existed. But they didn’t know how accessible it was via the Atlantic.
But never mind, it’s good to see someone putting numbers to a prediction. At least one specific thing is available for discussion.
See also: Could ultraviolet light mean life throughout the universe?
But surely we can’t conjure an entire advanced civilization?
How do we grapple with the idea that ET might not be out there?