GE CLST 70B Lecture Notes - Lecture 18: Dark Energy, Global Warming, Proton Decay
31 Mar 2017
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Document Summary
Extraterrestrial life and the end of the universe. Et life is actually a very old and well-theorized field. Problem: we only have one example - us. What does life require: a place: planet, moon, asteroid, substrate, medium for chemistry, such as liquid water, method of inheritance: complex chemistry like rna/dna o o. There are 200 billion stars in the milky way alone. Planet detection in the last few years has shown that there are more planets in the mw than stars. Earth: carbon chemistry with water as the principle solvent: h, o, c, n are by far the most common elements everywhere in the universe, h2o is the most common molecule after h2 o. C is the most common building block for complicated chemistry: makes it likely that common life forms are cellular organism with some form of, other forms are possible but not probable. Liquid water: need this for carbon chemistry o.
