Human beings have been living their lives - hunting, sleeping and accidentally stubbing their toes on rocks & furniture - for roughly 200,000 years. This sounds like a long time, but when you compare it to the age of the observable universe (13.7 billion years), it’s less than a blink of an eye.
In that blink of an eye, we’ve gone from living a hunter-gatherer existence to sending robots to other planets in our solar system. Where our ancestors once had to brave the elements, we control them.
This relatively rapid technological boom is incredible for multiple reasons, but it also leads us to wonder how, in a universe that is billions of years old, we seem to be the only intelligent civilisation out there.
The Fermi Paradox is an interesting thought-experiment that poses the ultimate question: ‘where is everyone?’. If life can occur on Earth then surely it can occur elsewhere, and if life is commonplace then we should see signs of life scattered all over our galaxy.
The numbers are mind-melting. In 2016, astronomers discovered that the observable universe contains TEN TIMES as many galaxies as previously thought, bringing the overall number up to at least 2 trillion. That’s such a ludicrous number that you could give every single human being on Earth 280.7 galaxies EACH. And each of those galaxies contains billions of stars - some just like ours.
To figure out how many other civilisations there might be, we can use something called 'the Drake Equation'. Taking into account things like the average rate that stars form, the likelihood that a given star hosts a habitable planet (like ours), and the likelihood of complex life arising (like us), we end up with estimates ranging from ‘we’re totally alone’ to ‘there are millions of civilisations in our galaxy & Star Trek is real’.
As it stands, we have a sample size of just 1: Earth, and this means that the Drake Equation – and therefore all deductions from the Fermi Paradox - should be taken with a galactic pinch of salt.
WHAT TECHNOLOGY MIGHT THEY HAVE?
To delve deeper into the Fermi Paradox, we need to think about technology.
Technology is what separates us from the rest of the animal kingdom, and it seems inevitable that other technological civilisations would exhibit some kind of scientific or philosophical curiosity in much the same way that we do. But there’s every chance that the technology they use would be incomprehensible to our humble telescopes.
Just imagine showing an iPad to someone from the early 1900s. To their eyes, it would be (as Arthur C. Clarke famously claimed) indistinguishable from magic. In just over a hundred years, we’ve developed technology that our ancestors couldn’t begin to understand. Now imagine what a thousand years’ worth of technological progress might look like.
With enough time, intelligent civilisations might transcend their biology. Perhaps they turn inwards – embracing the quantum world, or a simulated existence that removes the harsh realities of living in space.
After all, there’s no reason to think that aliens would have the same colonial motivations that we do. In terms of distance, time and energy, colonising entire galaxies may be prohibitively difficult, even for hyper-advanced civilisations.
According to Carl Sagan, humanity is currently a Type 0.7 Civilisation on the Kardashev Scale. To become a Type I Civilisation, we would need to be able to harness the energy of the entire planet, with no waste. A Type II Civilisation would be able to harness all of the energy of their host star, and a Type III Civilisation could, theoretically, harness the energy of an entire galaxy.
The reason that astronomers look to the Kardashev Scale is that large-scale engineering projects (such as those built by a proposed ‘Type III Civilisation’) would be visible in our telescopes. The radiated waste left over by such large projects would be a tell-tale sign of intelligent life.
But up till now, we haven’t seen any signs of projects such as this. Why is that?
WHAT IS ‘THE GREAT FILTER’?
One possibility is that complex life is INCREDIBLY rare. This is often described within the context of an eerie concept known as ‘The Great Filter’, which describes how, at some point in a civilisation’s history, there are extinction-level obstacles that make intelligent life almost impossible.
It could be right at the beginning, at the point where single-celled organisms evolve into multi-cellular life. This would be great news for us, as it would mean we have – against all odds – slipped through the net and avoided The Great Filter. If, however, the Great Filter is ahead of us, then we should be very, very worried.
As it stands, the human race has developed the capacity to wipe itself out, in the cheery form of nuclear weapons. This could be an inevitable outcome of intelligence – selective pressures leading to competition, violence and finally technology, which then leads to an upward spiral of war, technological progress and, finally, self-obliteration. This is hardly something you’d want to write in a Christmas card.
Various pandemics, Ice Ages and environmental catastrophes could also be a sign that Life is far more fragile than we currently realise, and the only reason it seems so normal to us is that we are, potentially, the only ‘success story’ in the universe.
So as far as ‘The Great Filter’ goes, no news is good news.
THERE ARE NO ANSWERS...YET.
The Fermi Paradox is an intriguing question that leads us to just two terrifying possibilities; we’re either alone in the universe, or we’re not.
As of January 1st, 2018 there are 3726 confirmed exoplanets, orbiting 2792 different stars (with another 5000 awaiting further investigation). International organisations such as SETI (the Search for Extra-Terrestrial Intelligence) are busy working day and night to try and find signs of intelligent life elsewhere in the universe. As our telescopes get more and more refined, it may just be a matter of time.