As Snyder-Beattie explained in the article, the “Great Filter” is a response to the question of why we can’t see any alien civilizations. The “Great Filter” deals with similar issues as the Drake Equation, which talks about the probability of communicating civilizations outside of Earth, and the Fermi Paradox, which asks where the civilizations are. Simply speaking, the idea is that if a civilization continues to expand (especially at the technological pace we humans have experienced), it wouldn’t take all that long in the lifespan of the universe for artificial processes to be visible with our own telescopes. Yes, this...