In case you were wondering, cannibalistic space probes are probably not the reason we haven’t seen aliens yet, according to a UK researcher.
In a paper slated for publication in the International Journal of Astrobiology, and available in the pre-print library arxiv, computational astrophysicist Duncan Forgan explores one possible solution to a question that challenges our beliefs about humanity and our place in the universe – where is everyone?
People stargazing on a dark night sometimes idly mull over this question. Countless exoplanets spin around other stars, so it isn’t far-fetched to assume life – in particular, intelligent life – must have arisen on at least some of these worlds.
A fraction of these lifeforms should have developed the advanced technology to send out interstellar spacecraft, and although travelling such vast distances across space would take a long time, the universe has been around for billions of years – so why haven’t we seen any trace of aliens yet?
This question is known as the Fermi Paradox, named for the Italian-American physicist who approached the problem with some mathematical rigour in 1950.
The paradox is strengthened when considering the possibility of exploring the galaxy using self-replicating probes – also known as von Neumann machines, after the mathematician who proposed the technology in the 1960s.
An advanced civilisation could launch a single probe with the capability to mine raw materials from other planets and asteroids in order to build a replica of itself. The probe and replica would then travel onwards to different solar systems to duplicate themselves again, and by repeating this process their population would grow exponentially.
In a relatively short space of time – perhaps as little as 10 million years – the galaxy would be teeming with these exploratory machines.
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