spaceSpace and Physics

If Aliens Visit Earth "They Won't Be Alive", Senior Astronomer For SETI Says

James Felton

James Felton

Senior Staff Writer

clockJun 16 2021, 16:30 UTC
Aliens visiting earth

If they come, they will not be alive. Image credit: IgorZh/

The way we imagine first contact with an alien species has evolved somewhat over the decades. Sci-fi usually still goes with the classic trope of a ship arriving one day out of the blue, without so much as a quick signal communicating via mathematics.

When they do show up to Earth, they are (by and large) portrayed as organic beings. But astronomers, physicists, and the good people at the Search for Extraterrestrial Intelligence (SETI) are slowly turning away from the idea that when we meet extraterrestrial intelligence, it will be anything like us. 


In an opinion piece for the Guardian, senior astronomer for the SETI Institute Seth Shostak has argued that if E.T. were to show up on our planet, the laws of physics mean that we are likely to encounter alien intelligence unlike anything we have on Earth.

"Any aliens that trek to our planet are unlikely to be carbon-based life forms, either hirsute or hairless," Dr Shostak wrote. "Their cognitive abilities will probably not be powered by a spongy mass of cells we’d call a brain. They will probably have gone beyond biological smarts and, indeed, beyond biology itself.

"They won’t be alive."


The reason for this, Shostak says, is that it isn't an attractive prospect for organic beings to dedicate their lives and their offspring's lives to the vast amount of time interstellar travel will take. Our fastest way of traversing space would take 75,000 years to reach our nearest star, Proxima Centauri. Even if we had solid evidence of life on Proxima Centauri b – the planet discovered in Proxima Centauri's habitable zone – it would be tough to persuade someone to commit their ancestors to travel through space on a generation ship for longer than it took humanity to go from just a few thousand people to 7.674 billion.

Though alien civilizations may be significantly more advanced than us, and the vast age of the universe they may have had to work on their tech, they still have to operate within the laws of physics. If they find a way to speed up travel, it'll come with the price tag of having to use up vast amounts of energy, and even then the distances involved will likely remove the possibility that it can be done within the lifetime of biological beings.

However, he argues, if you're willing to take your time you can traverse these distances. 


"Machines," he writes, "won’t complain if they’re cooped up in a spaceship for tens of thousands of years. They don’t require food, oxygen, sanitation, or entertainment. And they don’t insist on a round-trip ticket."

His ultimate takeaway for what they'll look like is that if they are machines, "who cares?".

Shostak has previously bet that within a few decades, humans will have discovered alien life out there in the universe, which he puts down to the speed of the search doubling every seven years.


“SETI doubles in speed roughly every two years because the speed is largely dependent on computers,” Shostak told The Debrief. “So just follow Moore’s Law, and you know, I bet everybody a cup of Starbucks that we’ll find something by 2036.”

[H/T: The Guardian]

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