Fermi Paradox and the Great Filter

One of the greatest questions that has baffled scientists, as well as all of humanity, is :

“Why don’t we see alien civilizations?”

We currently have knowledge that there are at least a hundred billion watery planets in our galaxy itself with probably billions being earth sized revolving around sun-like stars and in the Goldilocks Zone. These planets have been here long enough to produce civilizations that could have colonized the entire galaxy. Humanity has been on earth for merely 200,000 years while the galaxy is 10 Billion years old and we are able to send probes in space with our current technology. Thus given the age of the galaxy the logical conclusion is that there should be at least one other alien species which should be able to do the same. However, we have seen zero evidence of any current aliens or residual evidence of extinct ones.

Thus the question arises — why is the Milky Way unlike Star Wars?

This oddity is called the Fermi Paradox — the contradiction between the high probability of existence of extraterrestrial life and the lack of evidence to support this claim. The natural progression of a species after the domination of their planet would be spread to the solar system and then the entire galaxy. But we have seen no such evidence even though some Earth-like planets are billions of years older than us. This means something is preventing intelligent life from climbing this staircase beyond the step we are on right now. This something which makes becoming a galactic civilization extremely hard or probably impossible is called the Great Filter, a challenge or danger so hard to overcome that it eliminates every species that encounters it.

In the case of humanity there are two possible scenarios :

The first being that we have already passed the filter, in which case we can assume that the impossible step which no other species on any other planet has passed is the development of intelligent, complex life itself and the possibility of conscious thought. The outcome being we are the first forms of intelligent life and are on the road to conquering the entire galaxy.

In Scenario Two the filter is ahead of us and the danger is vastly greater than anything the earth has experienced in its lifetime (ice age, life devastating comet) as the current devastating events have not managed to terminate life but only set it back on the path to intelligence by a small fraction. Thus the filter must be so dangerous, devastating and powerful that it has destroyed all advanced civilizations in our galaxy. The most convincing hypothesis is that once a species assumes complete control over its planet it has started on the path to self-destruction. Technology is the best way to achieve this. This thing needs to be so obvious that every intelligent species is able to discover this but also dangerous enough that its discovery leads to a crisis or disaster. Some examples may be — nuclear war, artificial intelligence that gets out of hand, experiments that destroy the atmosphere and genetically engineered diseases. It may also be something simpler such as the species destroying the planet while competing with each other for its resources. Once a civilization is advanced enough to change the composition of its planet, it ends up making it uninhabitable.

These two scenarios would also lead us to the logical conclusion that finding extra-terrestrial life is actually an indication of danger as it would mean that scenario one is false and that the filter is ahead of us. But until then live long and prosper.