GS1004 Spotila 24 August 2016 Lecture 1: The formation of Earth Supporting reading: Chp. 1, p. 10-22. Motivating questions: Where did the Earth come from? How did it evolve into this organized form? Where did the material (elements, atoms) of the Earth originate? When did all this happen? The Universe as we know it evolved following the Big Bang : A sudden “explosion” from a single, infinitely dense point (energy only, no atoms) at the center of the Universe; ~13.7 b.y. ago. Big Bang theory does not explain why the bang occurred, but was constructed to explain observed consequences. What observations? 1) : Elemental abundancies/Big Bang nucleosynthesis First few seconds: hydrogen forms After 3 minutes: hydrogens can fuse into helium atoms By 5 minutes: process complete; first 5 elements exist (H 2 , He, Li, Be, Bo) Why did fusion occur? Because of the amount of energy that existed after the explosion How do we know? Looking at the distribution of elements in the universe LOOK-UP ITEM I: define "fusion"; review the basic nature of atoms (p. 16-17).
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