We know that the Search for Extraterrestrial Intelligence (SETI) is often strapped for cash. But what if the aliens out there trying to reach us, rather than being far superior technologically and beaming signals in all directions, are actually starving scientists, too?
In a pair of papers in Astrobiology, three members of the Benford family—Gregory, an astrophysicist and sci-fi author; James, president of Microwave Sciences; and James’ son Dominic, of NASA—ponder the possibility of E.T. trying to reach us on a budget, and say that we might have to revise the way we hitherto have watched.
Aliens wishing to communicate would probably broadcast at frequencies between 1 and 10 gigahertz, where there is less astronomical background noise than in other wavebands. Most SETI projects tune in to the “cosmic water hole” waveband between 1.42 and 1.72 gigahertz. The reasoning goes that alien astronomers might expect earthly scientists to be looking there anyway as this is the frequency of radiation emitted by interstellar hydrogen and hydroxyl clouds [New Scientist].
If you’ve been expecting to hear from a far-off alien civilization, don’t hold your breath, suggests Frank Drake, the founder of Search for Extraterrestrial Intelligence (SETI)–the odds of ET phoning Earth may be diminishing. And your digital TV might well be to blame.
Speaking at a meeting of the Royal Society in London, Drake said that digital transmissions are effectively “gagging” the planet. In the fast-fading analog age, TV and radio signals transmitted around the world escaped into space. At present, the Earth is surrounded by a 50 light year-wide ”shell” of radiation from analogue TV, radio and radar transmissions, he said [The Telegraph]. Those signals reach distant stars, which means that if someone is home at any of those stars, they could heard us.