Astro 101 11-17

Astro 101 11-17 - Abundance of other light elements agree...

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Astro 101 11-17 Look in one direction see 10 billion light years, look in opposite direction 10 billion light years. Those two galaxies don’t see each other. Content of Universe Dark Energy 73% Cold Dark Matter 23% Atoms 4% Even more of universe is unknown to us than we thought Cosmic microwave background radiation Observed patterns of structure in universe agree (so far) with the big Bang theory. Inferred from CMB Overall geometry is flat Total mass + energy has critical density Ordinary matter = 4.4 % total Total matter = 27% Age ~ 13.7 B Constraints on other parameters, when first stars formed, masses and number of neutrinos etc How do abundances of elements support the Big Bang theory? Protons and neutrons combined to make long lasting helium nuclei when universe was 3 minutes old Big Bang theory prediction: 75% H, 25% He (By mass) Matches observations of nearly primordial gases
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Unformatted text preview: Abundance of other light elements agree with BB theory having 4.4% normal matter Mysteries the BB theory doesn’t quite solve 1) where does structure come from? 2) Why is the overall distribution of matter so uniform/ 3) Why is the density of the universe so close to the critical density? Inflation can make all the structure by stretching tiny quantum ripples to enormous size These ripples in density then become Inflation of universe flattens overall geometry like, the inflation of a balllon is causing overall density of matter plus energy to be Olber’s Paradox If Universe were 1) infinite 2) unchanging 3) everywhere the same The inverse square law cancels the number of stars at the distance r Area of sphere Night sky is dark because the universe changes with time. As we look out In space, we can look back to a time when there were no stars...
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Astro 101 11-17 - Abundance of other light elements agree...

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