Cosmological principle

Definition

The cosmological principle states that the universe is homogeneous and isotropic when viewed on a large enough scale. This means that the distribution of matter and energy is uniform, and the universe looks the same in all directions.

5 Must Know Facts For Your Next Test

1. The cosmological principle underpins many modern cosmological models, including the Big Bang theory.
2. Homogeneity means that any large volume of space contains roughly the same amount of matter.
3. Isotropy means that observations of the universe's properties are consistent regardless of direction.
4. This principle simplifies equations in cosmology by assuming uniformity in space.
5. Evidence for the cosmological principle includes the cosmic microwave background radiation and large-scale galaxy surveys.

Review Questions

• What does it mean for the universe to be homogeneous?
• How does isotropy relate to our observations of distant galaxies?
• What evidence supports the cosmological principle?

Related terms

Big Bang Theory: The prevailing model explaining the origin and evolution of the universe, starting from a singularity about 13.8 billion years ago.

Cosmic Microwave Background Radiation: Thermal radiation left over from the time of recombination in Big Bang cosmology, providing strong evidence for an isotropic universe.

Large-Scale Structure: Patterns of galaxies and matter on scales larger than individual galaxies, supporting homogeneity across vast distances.