spaceSpace and Physics

Scientist Suggests Why We May Not Have Heard From Aliens Yet


Jonathan O'Callaghan

Senior Staff Writer


Could life be locked under Saturn's moon Enceladus? NASA/JPL-Caltech

A scientist has taken a fresh look at the Fermi Paradox – essentially, why haven't we found aliens yet? – and suggested that one explanation is that most life could be sealed off from the outside.

Writing in the Journal of the British Interplanetary Society (a pre-print is available on arXiv), David Clements from London’s Imperial College tackled the oft-repeated paradox that if life was common, it’s a bit surprising we haven’t found anything yet.


“We conclude that the necessities of life – liquid water and sources of energy – are in fact quite common in the Solar System, but most potential sites are beneath the icy surfaces of gas giant moons,” he writes.

“If this is the case elsewhere in the Galaxy, life may be quite common but, even if intelligence develops, is essentially sealed in a finite environment, unable to communicate with the outside world.”

In the paper, he notes that water is essential for life, and it may be located beneath icy moons like Jupiter’s Europa and Saturn’s Enceladus. In theory, he notes, they could host “much larger ecosystems than the one that is present on the Earth.”

And he says that life appears to have emerged quite rapidly on Earth when the conditions were suitable. This suggests that “life can emerge wherever there is a compatible environment,” and may hint that there are discoveries waiting to be made.


Speaking to Newsweek, Clements said there were “a number of missions and observing facilities coming up over the next 10-20 years that will significantly boost our ability to detect life elsewhere.” These include missions like NASA’s Europa Clipper, or the James Webb Space Telescope (JWST).

None of these are likely to find life directly, however. Moreover, they will simply give us a better picture of what sort of habitable environments, if any, exist in our Solar System and beyond. Actually finding life may be a little bit more tricky.

At any rate, Clements says this all relates to the Fermi Paradox because “we know that species that live in water can evolve to a high level of intelligence.” So peering into these oceans could help us resolve the problem, but therein also lies an issue.

“We are left with the rather chilling prospect that the galaxy may be filled with life, but that any intelligence within it is locked away beneath impenetrable ice barriers, unable to communicate with, or even comprehend the existence of, the universe outside,” he said. Lovely stuff.


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