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. Image courtesy of NASA/jpl-Caltech/Ames

Did climate change destroy the aliens?

Italian physicist Enrico Fermi had a knack for back-of-the-envelope calculations. In a famous lunch-time conversation in 1950, Fermi used his knowledge of astronomy and probability to highlight a problem: If intelligent life exists elsewhere in the galaxy and if long-distance space travel is achievable, then Earth should have been visited by aliens by now.