Fermi Paradox
It is statistically improbable that there has never been any other life in the universe except ourselves. The Fermi Paradox asks, given this improbability, why have we not heard from life other than our own? Is it inevitable that all life thrives and inevitably dies?
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.