ASTRON 100 Lecture Notes - Galaxy Formation And Evolution, Weakly Interacting Massive Particles, Large Hadron Collider
21 Jan 2014
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Document Summary
Dark matter, dark energy, and the fate of the universe. Dark matter: an undetected form of mass that emits little or no light, but whose existence we infer from its gravitational influence. Dark energy: an unknown form of energy that seems to be the source of a repulsive force causing the expansion of the universe to accelerate. We measure the mass of the solar system using the orbits of planets: A plot of orbital velocity versus orbital radius. The solar system"s rotation curve declines because the sun has almost all the mass. The rotation curve orbital velocity rises with radius. The rotation curve of the milky way stays flat with distance. Mass must be more spread out than in the solar system. Mass in the milky way is spread out over a larger region than its stars. Most of the milky way"s mass seems to be dark matter.
