The Fermi Paradox: A 10 Step Guide To Finding Aliens

5. The Great Filter

So, considering we haven't spotted any evidence of a galaxy-wide alien colony (something that's tricky to keep hushed up), there must be something stopping civilisations hitting the Type III mark. This is what is known as The Great Filter.

The Great Filter (hereafter referred to as TGF for brevity and laziness) is a barrier somewhere along the evolutionary journey that all life must hit and is extremely unlikely to survive. There is no definitive answer as to where along the journey to civilisation this barrier occurs, but the answer is very important, not only for our search for extraterrestrial life, but for the future of the human race.

Really, there are only two places TGF can lie in relation to humanity: Behind us or ahead of us. This is because, if we find out that TGF is behind us, and we're one of the few, if not the only, civilisation to make it through, then it answers a lot of our questions about the nature of life in the universe.

If, however, we find out that it is still ahead of us, then we could be flying straight towards an extinction event.