AST 101 Lecture Notes - Lecture 19: Hubble Space Telescope, Reionization, Background Radiation
Document Summary
Motion of galaxy is due to the expansion of the universe over time. Photons converted into particle-antiparticle pairs and vice versa. Expansion impacts light too, causing it to increase in wavelength. Galaxies move apart as the space between them expands. As space expands light becomes redshifted. The early universe was full of particles and radiation because of its high temperature. Drop in temperature leads to stable particles. Amounts of matter and antimatter are nearly equal. (roughly one extra proton for every billion proton-antiproton pairs) Began when matter annihilates remaining antimatter at . 001s. Helium nuclei formed at age of 3 minutes. The universe became too cool to blast helium apart. Left with 75% h, 25% he by mass. Free electrons combined with h and he nuclei to form atoms at age of 380,000. Universe consists of neutral hydrogen and helium gas. No stars no light producing objects. Universe is dark, although light could propagate if presents.
