Where were we?
This year we have Darwin's 200th birthday and the 150th anniversary of the publication of On the Origin of Species. It's a natural time for thoughts to turn to issues about the origins of life and the trajectory of biological evolution. It was in that context that I found myself, this week, thinking again about the Fermi paradox and the mysteries of the Drake equation, after some discussion of these over on Richard Dawkins' site. The discussion on Dawkins' site got a bit acrimonious, for some reason, but I'm sure we can avoid that here.
At the end of Part 1., I left the Fermi paradox with questions about the fate of technological civilisations. Do they self-destruct? Do they become unrecognisable to us? Or does the rate of technological progress flatten out, in which case we are not approaching a technological singularity – rather, we are somewhere on the steep part of a sigmoid curve.
Deeper into Drake's equation
I suspect that the evidence that we're on a sigmoid curve is pretty much illusory. E.g., the evidence from science fiction is probably just evidence of limits to our imaginative capacities. Still, it's not a scenario that can be ruled out (and it seems just as possible to me as the technological singularity scenario). It's certainly conceivable that at least some kinds of technological progress flatten out. At 1 per cent of the speed of light it would take us over 400 years to reach the nearest stars. We don't know how much longer to reach the nearest worlds that could easily be colonised. We tend to think that the problems will be solved in millions of years of future progress, but we may not be good at working out what problems can and cannot be solved, at least easily enough to be worth the effort, even over very long tracts of time.
That said, I'd prefer to look for an explanation deeper in the Drake equation, which uses several variables to calculate the number of technologically advanced species in our galaxy. The variables include the average rate of star formation, the fraction of stars that have planets, the fraction of planets that can potentially support life, the fraction of these that actually develop life, the fraction of these where intelligent life evolves, the fraction of these that develop civilisations that send detectable signs of themselves into space, and the length of time that such civilisations exist.
Some of the fractions that feed into the Drake equation may be very small indeed, so small as to make technologically advanced species, and the civilisations they create, incredibly rare. It's consistent with what we now know that the conditions required for life to form are extremely fortuitous and unusual. It may need very rare combinations of environmental factors. And even then, you can have life staying at levels of neurological complexity that don't lead to technology.
We know that life can stay at levels of intelligence well below our own pretty much indefinitely. If not for one or more catastrophic events at the end of the Cretaceous Period, including the bolide impact that caused the Chicxulub Crater, Earth might still be dominated by dinosaurs, which might not have developed any impressive levels of intelligence. They hadn't done so in the previous 150-odd million years, so there's no reason to think they would have in the past 65 million years.
We really need to know a lot more, and we soon reach a point where people are relying on nothing more than hunches. With that disclaimer, my hunch is that the evolution of a technological civilisation to our sort of level or beyond is a statistically improbable event. I.e., it is an event that takes place quite infrequently in an average galaxy. I can't be much more precise about what "quite infrequently" means, except to say that I wouldn't be at all surprised if human beings were the only species in our galaxy to have created technological civilisations.
There's a lot of things we'd need to know before we could say anything more confidently, or more precise, than that. E.g., we'd need a well-corroborated theory of the origin of life to give us an idea of how rare the conditions for it really are. We just don't have one. We have a well-corroborated theory of how life diversifies - neo-Darwinian evolutionary biology - but not of how it gets started. The best we have is an idea of what sort of theory would be a workable account of abiogenesis – some kind of theory of early kinds of self-replicating molecules that were able to develop into the building blocks for the kinds of life forms from which we, and the rest of contemporary life on Earth, all eventually diversified.
There are so many unknowns about all this that I think we're a long way from being able to deduce any pessimistic conclusions about humanity's future. Even if life itself is more common in the universe than appears so far, the evolution of human-level intelligence might be very rare indeed. Even if technological change ends up following a sigmoid curve, we don't know how to unpack the detail of that – it might mean that space travel at appreciable fractions of the speed of light is going to turn out more difficult than we commonly assume … but, for all that, our ability to transform our capacities may reach levels far beyond what is current. We can't predict the future, though we can forecast and consider various possibilities and scenarios.
Meanwhile, I'm still waiting for my alien civilisation. I'm also waiting for my jet car. If it doesn't turn up before I shuffle off this mortal coil, I don't know if that's a reason for pessimism or optimism.
Where has the damn thing gone?
Russell Blackford is an Australian philosopher. He has published extensively (novels, short stories, academic monographs and articles, and book reviews) and is editor-in-chief of The Journal of Evolution and Technology. His home blog is Metamagician and the Hellfire Club.