By measuring galaxy redshifts, Hubble found distant galaxies recede faster than closer ones. This relationship, Hubble’s law, shows the universe is stretching like a balloon. It implies that the universe was once compact. Expansion continues today, accelerating due to dark energy. Observing this expansion allows estimation of the universe’s age. It confirms the dynamic, evolving cosmos predicted by the Big Bang.
Hubble’s expansion matters because it directly supports the universe’s explosive origin.
It also helps determine distances, cosmic age, and the influence of dark energy.
Galaxies are flying apart, a sign the universe is expanding from its fiery birth.
Hubble Space Telescope [hubblesite.org]