Astronomy 1021 Chapter Notes - Chapter 17: Night Sky, Structure Formation, Dark Energy

• School: Western University
• Department: Astronomy
• Course: Astronomy 1021
• Professor: Chris Racknor

Document Summary

If the expansion of the universe causes the distances between galaxies to increase, they must have been closer in the past. Which means temperature and density of the entire universe were higher in the past. If the expansion of the universe has always existed, all matter must even have been at the same single point in the beginning o. Using einstein"s general relativity equations to backtrack the evolution of the universe results in an infinitely dense and infinitely hot universe in a finite amount of time o. That well-defined point in time is dubbed the big bang. The scientific theory that the entire universe started from an incredibly tiny, hot and dense collection of matter and radiation that evolved following well-known and tested laws of physics, is called the big bang theory. It does not explain why the universe came into existence o. It explains how it evolved right after that.