lecture03-1

lecture03-1 - 1 Extraterrestrial Life: Spring 2008 Why is...

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Unformatted text preview: 1 Extraterrestrial Life: Spring 2008 Why is carbon not formed in the Big Bang? Carbon is formed from the reaction: 4 He + 4 He " 8 Be 4 He + 8 Be " 12 C `Triple alpha process Problem: beryllium 8 is unstable - decays with a half life of ~10-16 s Reaction is possible: given enough time (stars, not the Big Bang) due to fortuitous resonance that favors the 2nd step of the reaction Extraterrestrial Life: Spring 2008 Anthropic Principle If the laws of physics were different (in some cases in quite minor ways) life might not be possible Astronomical examples: if the Universe started off denser than it was, would have collapsed to a Big Crunch before life could have started if the dark energy were stronger, Universe would expand too rapidly to form stars possible to imagine nuclear physics such that heavy elements never form planetary orbits with n > 3 dimensions?...
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This note was uploaded on 08/31/2009 for the course GEOL 3300 taught by Professor Staff during the Spring '08 term at Colorado.

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lecture03-1 - 1 Extraterrestrial Life: Spring 2008 Why is...

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