Universe known there are at least 100 billion galaxies, each containing 100 to 1000 billion of stars. Based on what we know of exoplanets, there are Katherine and Katherine potentially habitable: large numbers that suggest that we are not alone in the cosmos.
Is anybody there? But then, where is everybody? These two animations - in English with Italian subtitles - explore the basics of the Fermi paradox, the apparent contradiction (the unofficial formulation is commonly attributed to the Italian physicist Nobel Prize) in a simple and immediate between the high probability that the our civilization is not the only universe evolved and lack of contacts established with any other life.
No reply. The first video, you see at the beginning, explaining in what way the paradox. If just 0.1% of the Milky Way planets have life on it, there would be 1 million inhabited planets in our galaxy. How should we interpret the fact that we have never met E. T.? We are more fortunate than you think? There are "filters" that preclude knowledge of other life forms? Or are we really alone?
The second animation that you see below, offers some possible solutions to the Fermi paradox. Both videos were taken from the study of German design Kurzgesagt, specializing in advisory projects.
From Focus