It has produced one of the most consistent sets of negative results in the history of science. For more than 60 years, researchers have tried to find a single convincing piece of evidence to support the idea that we share the universe with other intelligent beings. Despite these decades of effort, they have failed to make contact of any kind.
But the hunt for alien civilisations may be entering a new era, researchers believe. Scientists with Breakthrough Listen, the world’s largest scientific research programme dedicated to finding alien civilisations, say a host of technological developments are about to transform the search for intelligent life in the cosmos.
These innovations will be outlined at the group’s annual conference, which is to be held in the UK for the first time, in Oxford, this week. Several hundred scientists, from astronomers to zoologists, are expected to attend.
Astronomer Steve Croft, a project scientist with Breakthrough Listen, said: “There are amazing technologies that are under development, such as the construction of huge new telescopes in Chile, Africa and Australia, as well as developments in AI. They are going to transform how we look for alien civilisations.”
Among these new instruments are the Square Kilometre Array, made up of hundreds of radio telescopes now being built in South Africa and Australia, and the Vera Rubin Observatory that is being constructed in Chile. The former will become the world’s most powerful radio astronomy facility while the latter, the world’s largest camera, will be able to image the entire visible sky every three or four nights, and is expected to help discover millions of new galaxies and stars.
Both facilities are set to start observations in the next few years and both will provide data for Breakthrough Listen. Using AI to analyse these vast streams of information for subtle patterns that would reveal evidence of intelligent life will give added power to the search for alien civilisations, added Croft.
“Until now, we have been restricted to looking for signals deliberately sent out by aliens to advertise their existence. The new techniques are going to be so sensitive that, for the first time, we will be able to detect unintentional transmissions as opposed to deliberate ones and will be able to spot alien airport radar, or powerful TV transmitters – things like that.”
The importance of being able to detect civilisations from the signatures of their everyday activities is supported by astrophysicist Prof Adam Frank of the University of Rochester in New York. “By searching for signatures of an alien society’s day-to-day activities – a technosignature – we are building entirely new toolkits to find intelligent, civilisation-building life,” he writes in his new book, The Little Book of Aliens.
All sorts of technosignatures have been suggested as indicators of the presence of alien civilisations, from artificial lighting to atmospheric pollution. Some scientists have even suggested that alien civilisations could be spotted from the solar panels they have built. Solar panels absorb visible light but strongly reflect ultraviolet and infrared radiation, which could be detected using a powerful telescope.
However, this would only be possible to spot if vast tracts of a planet’s surface had been covered in solar farms and hundreds of hours of observing time were committed to such a search, says astrobiologist Lewis Dartnell, writing in the latest edition of the BBC’s Sky at Night magazine.
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Other alien efforts to trap solar radiation could be even more elaborate and conspicuous, however. The US physicist Freeman Dyson once proposed that some civilisations might be advanced enough to build vast arrays of solar panels encircling their home stars. These great orbiting edifices – known as Dyson spheres – would be detectable from Earth, and several candidates have been proposed, including Boyajian’s star, in the constellation Cygnus, whose output of light is sporadic and unpredictable. Some suggested this could be being caused by a Dyson sphere, though recent observations have ruled out the possibility.
The hunt for alien civilisations has been a cornerstone of cinematic sci-fi spectaculars from E.T. to Contact, Arrival and District 9. However, extraterrestrial life forms have remained the stuff of fiction, despite efforts which began in earnest in 1960 when astronomer Frank Drake used a 26-metre radio telescope to search for possible signals from the stars Tau Ceti and Epsilon Eridani. None were detected – a state of affairs that has continued despite vast increases in the power and sophistication of modern telescopes.
Whether this stream of negative results continues remains to be seen. Croft remains optimistic that we will soon succeed in making contact. “We know that the conditions for life are everywhere, we know that the ingredients for life are everywhere.
“I think it would be deeply weird if it turned out we were the only inhabited planet in the galaxy or in the universe. But you know, it’s possible.”
