Some Thoughts on SETI and the Fermi Paradox

The Fermi Paradox, named after the physicist Enrico Fermi, asks why humans have had no contact with, and found no trace of, alien civilisations, given that even conservative estimates of how many such civilisations should exist suggest that our galaxy should be teeming with them. The Search For Extraterrestrial Intelligence (SETI) has been ongoing for several decades now, but no unambiguous artificial signal from space has ever been detected.

One answer to the paradox is that they just aren’t out there, which would mean that our planet is the first to develop a technological society. Alternatively it might mean that such societies destroy themselves quite early on, in which case Humanity’s life expectancy may be on the short side.

Another popular answer is that relatively backward cultures like ours are insulated from galactic society, so as to let us develop at our own pace.

This reminds me of those occasional discoveries of a tribe in the Amazon rainforest, isolated from the rest of the world. Should we make contact with them, potentially ruining their pristine existence? Personally I would be gutted to discover that an advanced civilisation had been treating humanity in this way—isolating us from their advanced culture and science. Particularly medical science. (Though if they ever read this, I point out that I’d be more than happy to let bygones be bygones.)

I wonder, though, whether the reason we haven’t picked up radio signals from aliens is that a technologically advanced civilisation quickly finds a better way of communicating than through broadcasting radio waves.

I could just throw words and phrases around at this point, sounding like techno-babble from an episode of Star Trek, so that’s what I’ll do. Perhaps they use beams of neutrinos instead of radio, or gravity waves? That would be bad news for SETI, as our ability to detect either of those is still pretty basic, impressive though it is to be able to do it at all.

However, what if advanced civilisations do still use radio, but in a focused beam form? I don’t know how feasible this is, but armed with the confidence that only large amounts of ignorance can provide, it seems to me that if you can do it for visible light with a laser, and given that light and radio are just different wavelengths of electromagnetic radiation, radio beam technology sounds like a mere engineering detail for a sufficiently advanced culture.

If an alien race is communicating between the stars with some form of focused radio beam, we on Earth wouldn’t be able to pick it up unless Earth happened to be in alignment with the beam’s source and intended target. So maybe, when thinking about candidate stars to point SETI at, we should look out for alignments between two candidate stars and Earth.

By happy chance humans have reached the point where we know the orbits of increasing numbers of exoplanets—planets outside our solar system. As an inhabited star system might feature interplanetary messaging, we could also concentrate on times when two exoplanets orbiting the same star are in alignment with Earth.

I’ve been hoping that humans would discover alien life ever since I was a child watching Lost in Space. Half a century later, I would settle for finding microbes on Mars, but I’m still hopeful I’ll live long enough to learn that the human race is not alone in the galaxy.

My Thoughts on the Fermi Paradox

Enrico Fermi famously asked why, if our galaxy really does contain other intelligent, technologically capable species, we haven't seen any trace of them. Against the great age of the galaxy, the time required for a civilisation to explore every single star system in it is relatively small, so we should have encountered a probe or something by now. That we haven't would imply that in fact intelligent life is not very common.

Speaking personally, I would very much like there to be intelligent extra-terrestrial life. I largely grew up on Science Fiction, so the possibility of humanity one day making contacts with aliens featured highly in my formative years. Ironically, I automatically assumed that ET would be friendly towards Humanity, despite this rarely being the case in SF films and books.

To rebut the Fermi Paradox I used to reason that ET would very likely be thousands or even millions of years more advanced than us, and so would have little interest in making contact with a such primitive species as we would seem to them. Indeed, they might not even recognise us as being intelligent enough to be contactable. A second line of defence was that perhaps we have observed evidence of them, but have wrongly constructed naturalistic theories to explain the evidence.

Recently a third possibility has occurred to me. I wonder if we're being a bit parochial in our assumptions about what an advanced civilisation would do. Sure, it seems natural to us that they would expand out from star system to star system, building that Galactic Empire I used to read about, but maybe your needs and aspirations change as your civilisation advances. When our culture looks into the future we typically have a time frame of no more than a few decades. Many of our politicians seem to look little further than the next election, so that's probably not surprising. I'd hope, though, that this would change eventually. A sufficiently advanced culture might conquer problems like ageing and death, and start to think on a far longer scale. When your potential lifespan might be measured in millions of years, and remote possibilities morph into inevitabilities, you might become rather risk-averse. Galaxies contain supernovas, wandering planets, and who knows what other perils. Sure, their advanced technology might allow them to, say, relocate away from a star that would one day explode, or maybe even dismantle the star to stop it going off at all. But an easier solution might be just to leave the stars behind.

I wonder now if the missing alien civilisations aren't to be found in intergalactic space, millions of light years from anything that could harm them. According to David Deutsch in his book The Beginnings of Infinity (an excellent book, by the way), the density of matter is thin indeed out there, but a volume the size of the Solar System would still contain over a billion tonnes of matter, mostly Hydrogen. A sufficiently advanced civilisation, perhaps one that has moved from organic lifeforms to some form of miniaturised cyber-existence, might manage quite well.

'Might' seems to be the operative word in this post, so I'll permit myself to finish with another piece of even wilder speculation. Maybe a sufficiently advanced civilisation gets the option of abandoning ordinary matter completely, and migrates to dark matter. Then passing threats can be ignored as they'll just pass straight through you.

Additional: maybe this is how you'd do it.