Call me weird, and many have, but I have long been fascinated by the Fermi Paradox. Now a couple of Australian scientists claim to have found a partial resolution.
Enrico Fermi was an Italian-American physicist who worked on the making of the atomic bomb. He once said, in the context of the search for extra-terrestrial intelligence (SETI), that the question was not, is there anyone out there, but where is everybody?
This is a subject that has puzzled scientists ever since it became possible to detect any signs of civilisation around nearby stars from their radio emissions. (Sorry, this one is a bit science-heavy, but as I say, it fascinates me.)
We know that the chemical building blocks for life are everywhere. We know that the home galaxy contains 400 billion stars, many of them not unlike the Sun. Surely somewhere life must evolved, and if so, should have eventually developed into a technological civilisation
We know today that the paradox is even more baffling because we know, as Fermi did not, that extra-solar planets exist, having found many hundreds of them. Some, in his time, had theorised that the solar system was a one-off. We now know that planets may be the rule around stars, rather than the exception. There is still no one out there.
There have been any number of solutions put forward to the Fermi Paradox. There is the Shotgun Hypothesis – something or someone is deliberately wiping out technological civilisations as they emerge, for whatever reason.
The most accepted solution is the Great Filter Hypothesis. Something prevents the development of life from getting beyond a certain stage. Some think the Great Filter may still be ahead of us, and that technological civilisations may inevitably be doomed to fail in their early stages, by war, resources depletion, whatever.
Now two astrobiologists – such a discipline exists, this is a subject taken seriously by scientists – from the Australian National University have evolved their own version of the Great Filter. We know that when life emerged on Earth, conditions were entirely hostile. It took the interaction of that primitive life with the Earth as it was then to create more favourable conditions, releasing greenhouse gases and modifying the atmosphere to make it suitable for more advanced life. This is the so-called Gaian Hypothesis.
The two scientists from Australia suggest that that modification of the atmosphere may not be automatic. It may not happen, even after primitive life emerges. This may be the Great Filter which prevents life from developing elsewhere, or more likely, making it less common. They point to Venus and Mars, where conditions were once more favourable but where the process never took place. Mars is frigid, Venus an overheated hell.
I would say this goes so far, but not far enough. My own thesis, which I have thought about for years, is that life may or may not be common. If I were looking in the solar system, I would look not on Mars but under the frozen surface of Europa, one of the Gallilean moons of Jupiter, where there is a liquid ocean of water.
Life probably exists, then, but I suspect intelligence may be very rare, the sort of intelligence that develops the use of tools and ultimately a technological civilisation. It may be a rare fluke of evolution, like a peacock’s tail, that only emerges under particular evolutionary pressures that seldom occur.
The dinosaurs were around 200 million years, some walked upright with hands containing fingers and what looked like opposable thumbs, but none evolved an intelligence sufficient to develop technology of the sort we use. (No, they didn’t, trust me. We’d know from the fossil record.)
Most people have a dim idea that evolution is an arrow that only points one way. That microbes emerge from the slime, evolve into small snail-like creatures, into dinosaurs, and then apes appear, evolving into Man. That this is an inevitable process.
This is a misreading of evolutionary theory. Evolution occurs with jumps forward, leaps backwards through mass extinction events, and then forward again into ever greater complexity. But nothing is inevitable. And intelligence may be rarer than we think.