ASTRO-110 Lecture Notes - Lecture 18: Cosmic Microwave Background, Electroweak Interaction, Planck Units
18 Sep 2020
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Document Summary
Universe must have been much hotter and denser early in time. At these extreme temperatures and densities photons converted into particle-antiparticle pairs and vice versa (e=mc^2) Early universe was full of particles and radiation because of high temperatures. Lasts from planck time (10^/43 sex) to end of gut force (around 10 ^-38. Lasts from end of gut force to end of electroweak force (10^-10 sec) Amounts of matter and antimatter nearly equal. Roughly 1 extra proton for every 10^9 proton-antiproton pairs. Begins when matter annihilates remaining antimatter at around . 001 sec. Helium nuclei form at age (3 min) Universe has become too cool to blast helium apart. Galaxies form at age about 1 billion years old. A good scientific model should make predictions which can be verified. The big band model makes two predictions which have been verified since the. The existence and characteristics of the cosmic microwave background. The expected he abundance in the universe.
