Expanding universe

Definition

The expanding universe is the concept that the universe has been growing continuously since the Big Bang. This expansion is evidenced by the observation that galaxies are moving away from each other.

5 Must Know Facts For Your Next Test

1. Edwin Hubble discovered that galaxies are receding from us in all directions, which supports the idea of an expanding universe.
2. The rate of expansion of the universe is measured by the Hubble constant.
3. Cosmic microwave background radiation provides evidence for the expansion of the universe.
4. Dark energy is believed to be driving the accelerated expansion of the universe.
5. The redshift observed in light from distant galaxies indicates their motion away from us, supporting the theory of an expanding universe.

Review Questions

• Who first provided observational evidence for an expanding universe?
• What does the Hubble constant measure?
• How does redshift provide evidence for an expanding universe?

Related terms

Big Bang Theory: A scientific theory that explains how the universe expanded from a hot, dense initial state.

Hubble's Law: The observation that more distant galaxies are receding faster, implying a uniformly expanding universe.

Redshift: A phenomenon where light from an object is shifted to longer wavelengths as it moves away, indicating its velocity relative to us.