The Fermi Paradox
This is my favorite article on the internet I think. It puts a bunch of numbers on the chances of other life in our galaxy. There are a lot of Earths out there:
So there are 100 Earth-like planets for every grain of sand in the world. Think about that next time you’re on the beach.
And goes on to talk about how many of them are much older than Earth, and it really seems like intelligent life should be all over the place. But as best as we can tell, it isn’t. The Fermi Paradox is about why not and potential answers.
My preference is Possibility 9:
Higher civilizations are here, all around us. But we’re too primitive to perceive them.