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.
