A great explainer video from the folks at Kurzgesagt.

The universe is unbelievably big – trillions of stars and even more planets. Soo… there just has to be life out there, right? But where is it? Why don’t we see any aliens? Where are they? And more importantly, what does this tell us about our own fate in this gigantic and scary universe?

http://feeds.boingboing.net/~r/boingboing/iBag/~3/jrxLfpWP6c4/where-are-all-the-aliens-vide.html