spaceSpace and Physics

Hibernating Aliens May Explain Why We Haven't Found Any Other Life Yet


Jonathan O'Callaghan

Senior Staff Writer


Fred Mantel/Shutterstock

Scientists have proposed a rather interesting reason for why we haven’t found aliens yet, a problem known as the Fermi Paradox (if life is so abundant, where is everyone?). They propose intelligent aliens could be in a state of hibernation, waiting for the universe to get colder so they can be more productive.

This idea was proposed in the Journal of the British Interplanetary Society, with a pre-print available on arXiv. The paper was written by Anders Sandberg, Stuart Armstrong, and Milan Cirkovic of the Future of Humanity Institute at the University of Oxford, and picked up recently by Gizmodo.


Some people think that a civilization much more advanced than our own might become a digital race. That is to say, they’ll live as artificial intelligence inside computers, doing away with more limiting fleshy bodies. Experts including Elon Musk have suggested this is a logical progression in the far future.

If we are not alone in the universe (which we have no evidence for yet), one could therefore further propose that an advanced alien race might have gone down this route. But in order to make the most of their new digital bodies, they might not like the universe at the moment.

The temperature of the universe right now is 3 degrees Kelvin above absolute zero. That’s rather chilly, but that temperature will continue to drop as the universe expands. Sandberg and his colleagues argue that the temperature in the future could allow for 1030 more computational processes than are currently possible.

“We hence suggest the 'aestivation hypothesis',” the researchers write in their paper, adding that “the reason we are not observing manifestations of alien civilizations is that they are currently (mostly) inactive, patiently waiting for future cosmic eras.” Aestivation is basically hibernation to avoid hotter temperatures, not cooler ones.

Our universe is expanding at an accelerating rate. NASA's Goddard Space Flight Center

An advanced digital alien race might get to the point where they have fully explored a section of the universe. Finding no need to continue existence with a relatively limited processing power (processing becomes 10 times more efficient if your computer is 10 times colder), they may therefore choose to wait for a cooler age in the universe.

The authors do not necessarily think this theory is correct, not least because we have no evidence we are not alone yet. But they argue that if it turns out there is other life out there, then the theory is at least a possibility.

“[We] personally think the likeliest reason we are not seeing aliens is not that they are aestivating, but just that they do not exist or are very far away,” Sandberg wrote in a blog post. “If that hypothesis [life is rare] is not true, then aestivation is a pretty plausible answer in my personal opinion.”

What’s more, they propose a way to find aestivating aliens. If we can see unusual phenomena in the universe, such as stars failing to collapse into black holes, this might be evidence of aliens using up the energy. And if there are aliens monitoring our particular corner of the universe, then any attempts by us to travel outwards may be met with hostile resistance.


This theory will not be without its detractors. Science fiction author David Brin, for one, suggested to Gizmodo that it made little sense for a race to go into hibernation and waste processing time. The authors countered that any race would want to make the most of available energy, and thus wait for optimal conditions.

There’s no shortage of speculation these days about the Fermi Paradox, and the possibility of alien life. The fact remains though that – to paraphrase Arthur C. Clarke – we are either alone or not, and both answers are equally terrifying. Maybe, if we’re not, then there just might be sleeping aliens waiting for things to get a bit cooler.

(H/T: Gizmodo)


spaceSpace and Physics
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  • SETI,

  • aliens,

  • hibernation,

  • search for life,

  • aestivation