New technology means we can look for alien intelligence far further afield
SETI, the search for intelligent life beyond Earth, is having a bit of a moment. New techniques – including the ability to do what’s called commensal observing, monitoring for signals when telescopes are doing other things – have hugely increased the sensitivity of searches. Along with the expansion of observing programmes this makes possible, SETI scientists are thinking about searching in new ways, looking for laser signals among the stars, for signs that might betray the presence of very advanced civilisations, and for deliberate signals sent to coincide with major astronomical events, such as supernovae. Even searches for alien spacecraft lurking in the Solar System, which might be revealed by the next generation of telescopes, are being taken somewhat seriously.
We are also looking further than ever before. In this month’s paper, Carmen Choza, a student in Chicago working with the Breakthrough Listen team, uses data from the giant Green Bank telescope in West Virginia to search for signals coming from beyond the Milky Way. This is ‘traditional’ SETI, looking for narrowband signals broadcast over a small range of wavelengths with a radio telescope, but it is the most sensitive search ever attempted for intelligence beyond our own Galaxy.
Sending strong signals
Of course, any signal seen over intergalactic distances would have to be very powerful indeed. Assuming the aliens aren’t beaming a signal directly to us, but rather broadcasting blindly into the cosmos, the team conducting experiments reckon they would find signals over 1026 (a hundred million billion billion) Watts. Using the classification scheme introduced by Soviet astronomer Nikolai Kardashev in the 1960s, the team reckon that only Type II civilisations – those capable of harnessing all the energy from their star – would get close, but it still seems worth checking if they’re there.
As we’re not sure what sorts of galaxy might be amenable to int
