system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 what is the THE GREAT FILTER (Fermi Paradox) ?
gpt
The Fermí Paradox is that there are probably billions of habitable planets in our galaxy alone, and yet we don’t see any signs of sentient life up there in the sky. The Great Filter is one possible explanation of that. It goes that while there are many life-supporting worlds out there, there exists some barrier that is killing off alien civilizations before they can get to the scale where they would be detectable from Earth. For example, it could be environmental disasters caused by the civilizations themselves, or self-destructing nuclear wars, or something else entirely that we can’t foresee. The idea is somewhat frightening because humans as a civilization might be fast approaching that barrier.