Fermi Paradox

The Drake Equation: Given the size of the universe, extraterrestrial life should have contacted us (click to expand).

It is improbable that there is no life other than ourselves in the universe. The Fermi Paradox asks, given this statistical improbability, why have we not heard from aliens?

There is no known answer to this question hence the paradox bit. However, one possible solution is that technology and intelligence go in hand in hand and a great barrier is created for all intelligent species which in its 14 billion year history has tended towards only one answer. Life does exist, it has existed elsewhere, however before reaching the point where interstellar communication is possible the civilisation destroys itself, whether this is from war, overconsumption or disease the result is the same, looking at the sky we can see a dead universe.