A Set on edgi
Why the Sky Is Empty of Aliens
The math says the sky should be full of aliens. It isn't. Every explanation is worse.
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Fermi Paradox
The Fermi paradox exposes the clash between the high statistical odds of alien life across billions of stars and our complete lack of evidence for it.
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Copernican Principle
The Copernican principle states that Earth occupies an average position in space and that humans are not privileged observers of the universe.
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Drake Equation
The Drake equation is a mathematical formula that estimates how many active, communicative alien civilizations exist in our galaxy.
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Panspermia
Panspermia is the scientific hypothesis that microscopic life originated elsewhere and spreads across the universe inside rocks and comets.
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Rare Earth hypothesis
The Rare Earth hypothesis argues that simple life may be common, but complex, multicellular life requires an extremely rare set of circumstances.
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Anthropic principle
The anthropic principle explains that we observe physical constants suitable for life because observers cannot exist in a universe without them.
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Great Filter
The Great Filter argues that an evolutionary barrier makes advanced life rare.