The Fermi paradox is the alleged inconsistency between the lack of evidence of extraterrestrial intelligence and the various high estimates for its probability. The solution to the paradox has implications for the long-term future, in particular the feasibility of interstellar colonization and the likelihood of extinction.
The expected number of interstellar civilizations observable from Earth is the product of the number of planets in the galaxy and the following three probabilities:
The probability that any given planet produces intelligent life
The probability that any given intelligent species develops an interstellar civilization
The probability that any given interstellar civilization would be detectable from Earth at this time
Since the number of planets in the galaxy is in the hundreds of billions, even very small values of the three probabilities would imply that we should see many interstellar civilizations. However, we observe none. This means that at least one of the probabilities must be extremely low.
The second probability is most concerning, since it suggests something about the future of humanity. If it is the extremely low probability, then this means either that interstellar colonization is infeasible or that humanity is extremely likely to go prematurely extinct before engaging in it.
Generally, the more highly we rate the first and third probabilities, the lower the second probability would have to be, which should decrease our credence in the possibility of humanity ever leaving the solar system.
Further reading
Boeree, Liv (2018) Why haven’t we found aliens yet?, Vox, July 3.
Bostrom, Nick (2008) Where are they?, MIT technology review, April 22, pp. 72–77.
An exploration of the Fermi Paradox as it relates to the risk of human extinction
Ćirković, Milan M. (2018) The Great Silence: Science and Philosophy of Fermi’s Paradox, Oxford: Oxford University Press.
Miller, James (2020) The Fermi paradox and x-risk, AstralCodexTen Online Meetup, August 17.
Sandberg, Anders, Eric Drexler & Toby Ord (2018) Dissolving the Fermi Paradox, arXiv:1806.02404.
Wiblin, Robert & Keiran Harris (2018) Where are the aliens? Three new resolutions to the Fermi Paradox. And how we could easily colonise the whole universe, 80,000 Hours, May 8.
An interview with Anders Sandberg.
Related entries
extraterrestrial intelligence | grabby aliens | Great Filter | non-humans and the long-term future | space colonization | space governance
Good primer on the Fermi Paradox. Just what I needed. If you look at the human race (the only example we have) it appears that a species that has advanced to the point of space travel is also at the point of damaging its ecosystem to the point of threatening its own extinction. This was the premise of a great little story called The Fermi Paradox Is Our Business Model by Charlie Jane Anders.
Even if a species manages to safely navigate this point in its development, coming up with a stable society that includes space travel, the distances in space are exceedingly vast. Perhaps when we look at space, we’re seeing many planets teeming with life that we can never get to, while they can never get to us. It might be just as well. We don’t get along well ourselves; how well can we be expected to get along with aliens?
Not that we see those planets as they are now. We see them as they were, millions of years ago.