They talk about astrobiology and all the things that need to come together for life to occur. They are both very enlightening.
So many things need to happen just right for complex (animal) life to evolve and the universe just doesn't help contribute to that end. Not only do you need many specific conditions to be present like a habitable atmosphere, water, oxygen, moderate climate, iron core that creates magnetic field, tectonic plates etc. You need these conditions to be present and consistent for a billion years. And even if the planet was lucky enough to evolve complex life, the next step (intelligent life) is a huge leap. If the asteroid that killed the dinosaurs 66 million years ago hadn't happened the way it did, we most likely wouldn't be here.
The closest star is 4 light years away. If there happened to be a habitable planet around that star that had intelligent life and their spaceships could travel half the speed of light (highly unlikely), it would still take eight years to get to earth. Traveling eight years in a spaceship comes with its own challenges. Imagine stars that house intelligent life that are 100 light years away (which isn't that far in comparison), the trip would just take too long.
The prospect of another civilization from another planet visiting Earth has so many fascinating prospects that it's difficult to not want to believe it could happen.
But until ET shows up at the Capitol steps and says "Hi", I won't believe in Extraterrestrial Intelligent life.