Match the following. Match the items in the left column to the items in the right column.

1. cosmological principle
the universe looks the same at any location, but can change over time
2. cosmology
suggests the origin of the universe started with an explosion and expansion of a very hot, dense, compact fireball
3. galaxy
theory about the origin of the universe that suggests the universe is a never-ending cycle of expansion and contraction
4. big bang theory
the study of the origin and structure of the universe
5. oscillating universe theory
theory about the origin of the universe that suggests the universe has been and will continue to be as it is now
6. quasars
the oldest and farthest celestial bodies of the universe
7. steady state theory
a large-scale collection of stars, dust, and gas held together by gravity