hubble's law: meaning, definition, pronunciation and examples

It is named after the American astronomer Edwin Hubble, who published the observational evidence in 1929, building on earlier work by Vesto Slipher and others.

No, it describes the large-scale average motion of galaxies. Locally, gravity can bind objects together (like the Milky Way and Andromeda galaxies), causing them to move independently of the cosmic expansion.

The Hubble constant is the proportionality factor in Hubble's law. Its value gives the rate of expansion of the universe, typically measured in kilometres per second per megaparsec.

Hubble's law is an excellent description of the universe's large-scale behaviour for most of cosmic history. However, at very early times and possibly in the far future, the expansion rate changes due to factors like dark energy, so the simple linear relation may not hold.

The astronomical observation that the velocity at which galaxies recede from Earth is proportional to their distance from us, implying the universe is expanding.

Hubble's law is usually academic / technical / scientific in register.

Hubble's law: in British English it is pronounced /ˌhʌb.l̩z ˈlɔː/, and in American English it is pronounced /ˌhʌb.l̩z ˈlɔ/. Tap the audio buttons above to hear it.