Where Are The Aliens? How The ‘Great Filter’ Could Affect Tech Advances In Space:
Kepler-62f, an exoplanet that is about 40% larger than Earth. It’s located about 1,200 light-years from our solar system in the constellation Lyra. Credit: NASA/Ames/JPL-Caltech
“One of the main things we’re focused on is the notion of existential risk, getting a sense of what the probability of human extinction is,” said Andrew Snyder-Beattie, who recently wrote a piece on the “Great Filter”
for Ars Technica.
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 is even taking into account a presumed speed limit of no more than the speed of light. So something could be preventing these civilizations from showing up. That’s an important part of the Great Filter, but more details about it are below.
Here are a few possibilities for why the filter exists, both from Snyder-Beattie and from the person who first named the Great Filter, Robin Hanson, in 1996.
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