Astronomy 1021 Lecture Notes - Lecture 22: Big Crunch, White Dwarf, Cosmological Constant
4 Oct 2018
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Document Summary
W22l dark matter, dark energy and the fate of the. We"ve been building our understanding based on observations. Big band + inflation is the model so far that best explains what we see. Dm and de are now supported by careful scientific studies. Theories have slowly gained acceptance through testable predictions. If dm and de are not real, observations still need explaining. Motion of stars allows determinations of mass within. P^2= a^3 more distant planets take longer to orbit. Unlike in planets in the solar system, stars in galaxy orbit at roughly constant speed no matter how far from the centre of the galaxy. Solar system as mass concentrated at the centre. Galaxy can not have mass concentrated at the centre. Visible portion is at heart of a large halo of dark matter. More light per unit mass than the sun. Mass to light ratio of the milky way- 6. 7 m/l. Less light per unit mass than the sun.
