For as long as people have looked up at the sky and wondered, we’ve thought about whether there is anybody living up there? A thousand years ago or more we thought that the gods lived in the heavens but today we look, and listen with our radio telescopes to see if we can find any sign of alien intelligences out there.
After all there are simply so many stars in just our own galaxy the Milk Way, the latest estimate by astronomers is about 200 Billion! So even if only a very, very, VERY few stars have planets with civilizations on them there should be at least a hand full of other intelligent, technological species out there.
In 1961 the astronomer Frank Drake even thought up an equation to ‘estimate’ the number of civilizations ‘N’ there should be in the Milky Way. The equation starts with the number of stars in the galaxy, 200 billion and then multiplies that by a number of different factors:
P=The fraction of stars that have planets. Recent observations by the Kepler space telescope and other planet finding searches put this at least at 10% and perhaps as high as 50%.
G=The fraction of planets that are in the so-called ‘Goldilocks Zone’ where liquid water can exist. Here on Earth wherever there is liquid water there is life so biologists think that liquid water is essential to life. At present we have very little data about the value of G but based on our own solar system it’s around 20%.
L=The fraction of planets with liquid water where some form of primitive life does arise. Biologists have no idea what the value of this could be; some say it is probably as small as a few percent while others argue it could be as large as 90%.
I=The fraction of planets with some form of life where an intelligent, technically advanced species eventually evolves. The value of this fraction, your guess is as good as anybody’s.
So the Drake equation looks like this:
N=200Billion * P * G * L * I
And again, even if F, G, P, and I are all quite small when multiplied by 200 billion there should still be a dozen or so intelligent species in the Milky Way. Which again begs the question, why haven’t we found any yet?
Oh, my mistake, I forgot one last factor. You see when Drake thought up his equation he also considered the average lifetime of an intelligent, technological species, the factor ‘T’. After all, even if we don’t like to think about it species do go extinct. The trilobites all went extinct, the dinosaurs went extinct, so did the wholly mammoths. If an intelligent species lived on another planet 100 million years ago but has since gone extinct then we certainly wouldn’t be receiving radio signals from them today!
Recently a diverse group of thinkers, including space engineers, political scientists and just some smart people have taken a good look at that last factor and wondered, what if T is really small? What if being an intelligent, technological species is actually a short road to extinction? Remember out of the 4.5 billion years that Earth has existed our civilization has only been here for 10,000 years, a mere flicker of time. We have no real evidence that intelligent species survive any longer than non-intelligent ones do. Maybe they actually don’t survive very long at all.
Evolutionary biologists talk about ‘survival strategies’, having a bony, internal skeleton would be one example. That certainly is a good survival strategy, there are thousands of vertebrate species on Earth and they’ve been around for at least 450 million years. What about flying as a survival strategy, again there are tens of thousands of flying insects, birds, bats and there used to be flying reptiles as well.
So is intelligence a good survival strategy? You would think so at first sight. After all we now dominate this planet as no other single species ever has. We are so dominate that we’re even killing off thousands of other species, destroying whole ecosystems while we covert the planet to suit our pleasures of today and pay no attention to what the world is going to be like tomorrow.
By now I guess you see where I’m going with this. Do intelligent species actually destroy themselves by developing technologies they haven’t got the wisdom to properly use? The researchers, led by Jet Propulsion Labouratory engineer Jonathan H. Jiang, have christened this idea ‘The Great Filter’ that filters out, eliminates those species that allow their own technology to destroy them.
This idea isn’t completely new; back in the 1960s a lot of people were afraid that a nuclear war would destroy humanity. In the original Star Trek series Captain Kirk several times described the threat of nuclear war in the 20th century as “Our weapons outgrew our wisdom”. That line would be an early version of the Great Filter concept.
And the researchers do include a nuclear war as one of the possible ways that an intelligent species could destroy itself. The paper, which has been published on Cornell University’s Arxiv pre-print site, see link below, https://arxiv.org/ftp/arxiv/papers/2210/2210.10582.pdf, goes further however, including other man-made threats to ourselves like climate change and pollutants such as plastics and cancer causing forever chemicals.
Now the researchers also included one possible extinction cause that I’m going to have to argue against. In science fiction the idea of an Artificial Intelligence (AI) that supplants humanity is familiar from such movie series as The Terminator and The Matrix, and with the continuing development of cybernetics it is a definite possibility. However any such scenario would only represent one intelligence being replaced by another, perhaps better adapted intelligence. Such an event, whether here on Earth or on another planet would not cause the extinction of intelligence on that planet. Therefore I don’t think that AI should be included in the Great Filter.
With that one exception I find the paper’s analysis to be depressingly logical. The threats we are causing by our own selfishness and stupidity are real and growing. That’s why the Doomsday Clock maintained by the Bulletin of Atomic Scientists has recently been reset to a mere 100 seconds before midnight. There simply isn’t much time left for us to acquire the good judgment we need to solve all the problems we have created for ourselves. The wisdom we need to safely pass through the Great Filter.
That dilemma could, indeed probably is true for all intelligent species anywhere in the cosmos. As we sit warm and comfortable here on Earth it’s easy to ignore the fact that the Universe is actually a very hostile place for life. And maybe it is even more hostile to intelligence.