Astronomy 1021 Lecture Notes - Lecture 18: Inverse-Square Law, Deuterium, Cosmological Constant
22 Mar 2018
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Document Summary
Cdm model: lambda ( ) stands for dark energy , cdm stands for cold dark matter . Components of the universe: normal matter: ~ 4. 6, dark matter: ~ 24, dark energy: ~ 71. 4, dm and de are placeholders, data from planck space telescope + Dark matter and dark energy: dark matter. Interacts through gravity, but not light: dark energy. Sounds weird: dm and de are now supported by careful scienti c studies, theories have slowly gained acceptance through testable predictions, if dm and de are not real, observations still need explaining. Evidence for dark matter: milky way, other galaxies, galaxy clusters, fritz zwicky (1898-1974, vera rubin (1928-2016) Dm evidence 1: the milky way: motion of stars allows determination of mass within, results are shown in rotation curves. A plot of rotation speed vs distance from the centre: p2 = a3: more distant planets take longer to orbit, bigger orbits mean slower planets.
