AST201H1 Lecture Notes - Accelerating Expansion Of The Universe, Baryon, Dark Energy

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST201H1
• Professor: Michael Reid

Document Summary

There are small amounts of baryonic matter. 95% of universe is mysterious dark stuff. *clicker question: according to hubble"s law, distant galaxies are: Receding from us at an ever-increasing rate. Getting farther away at speeds proportional to their distances (this one) Moving through space, with farther ones moving faster: galaxies are not moving, but are getting farther away, distance to a galaxy is proportional to its redshift. Speed it up: every mass produces gravity, gravity can never push, only pull, as it cannot push, it can never speed things up. If expansion is slowing down, we would expect distant galaxies to have larger redshifts than predicted by hubble"s law. Would expect deviations in the upward curve of hubble"s law (decelerating expansion) We actually find an accelerating expansion curve. Today, universe is expanding faster than it was millions of years ago. Lower redshifts, and slower expansions farther back in history of universe.