The Big Bang Theory

Science’s explanation of how the universe originated

•Large and violent explosion 13.7 billion years ago

•This created many clouds of gas and dust

•Those clouds accreted to form solar systems and eventually galaxies

•ALL the elements came from this explosion, mostly H and He at first

•heavier elements formed later (inside the stars)

•the universe continues to expand, evolve, and cool

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•Quickly look over your notes and then summarize important concepts

60 second summary

๏how the universe began

Review #1What does the big bang theory try to explain?

Review #2What does accretion mean?

๏to clump together and stick

Review #3 Which 2 elements were there the most of after the big bang?

๏H and He

•evidence: recent data show low-level microwave radiation in the universe, only 3K, background “noise”

•this radiation is left over from the big bang

•as the universe expanded and cooled, the radiation waves stretched out