of chemical elements ¿t this prediction very well. Hydrogen accounts for about three-quarters of all matter, and helium for almost all the rest. Despite its bizarre conclusions, big bang cosmology offers a scienti¿c, welltested explanation of how the Universe was created. But the early Universe didn’t yet contain anything of much interest. In the next lecture we ask: How were the ¿rst stars and galaxies created? Ŷ
Essential Reading Brown, Big History, chap. 1. Chaisson, Epic of Evolution, Prologue, chap. 1. Christian, Maps of Time, chap. 1.
Supplementary Reading Bryson, A Short History of Nearly Everything, chap. 1. Coles, Cosmology, chap. 5. Delsemme, Our Cosmic Origins, chap. 2.
Questions to Consider 1. How persuasive is the evidence for big bang cosmology? 2. Why did it take astronomers so long to accept the implications of Hubble’s evidence that the Universe was expanding?
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