ASTRON 2B03 Study Guide - Final Guide: Cosmological Constant, Scalar Field, Weak Interaction

• School: McMaster University
• Department: Astronomy
• Course: ASTRON 2B03
• Professor: Christine Wilson

Document Summary

We don"t know what makes up most of the universe. Most of the universe (~70%) is made up of dark energy. The rest is everything else that we know exist and can test. Evidence for dark matter: motions of galaxies in clusters. If the planets are the only masses in the galaxy cluster then, at the velocities they are moving, they should escape the cluster and go out into space. Without extra mass the velocity would overcome gravity of the cluster. Found that there was a big difference in masses of galaxy clusters based on their speeds versus mass based on luminosity of the galaxies. Tons of mass unaccounted for in the galaxy: spiral galaxy rotation curves. Early evidence from rotating spiral galaxies in the milky way. Done by finding velocity of rotation from redshift and blueshift (vera rubin) Speed of rotation depends on amount of mass in orbit - more mass larger speed to compensate for increased gravitational attraction.