01:750:109 Lecture Notes - Lecture 2: Cosmic Calendar, Dark Energy, Dark Matter
19 Oct 2018
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Document Summary
Observation consistent with a universe that has been evolving and started becoming galaxies. Intergalactic clouds started collapsing - producing many stars. Stars are objects that shine - nuclear fusion generate heavier elements (anything from periodic table). Every element on the table involved a star doing something. 1999 and on: observations led us to realize there is more to it. Getting faster and faster (galaxies move away faster now than they did before) 2 hypotheses that involve the dark (what we cannot see) Dark matter to account for motion of stars, galaxies and clusters (do not know what it is) Dark energy ( energy - dont know what it is) to account for accelerating expansion of the universe. Other option: everything we know is wrong (not at the point to accept that) Everything we know accounts for only 5% Dark energy: 70% (don"t know what it is) In motion, goes around the sun - gives us seasons.
