Hubble’s law is the name given to observations in physical cosmology. Objects observed deep in space are found to have an interpretable Doppler shift at a relative speed away from the Earth, and the speed of various galaxies lagging behind the Earth, measured by this Doppler shift, is directly proportional to their distance for galaxies about a few hundred light-years away. This is normally interpreted as a direct observation of the expansion of the spatial volume of the observable universe.
The motion of astronomical objects, which is caused only by this expansion, is known as the Hubble flow. Hubble’s law is considered the first observable basis for the expanding space paradigm, and today serves as one of the most cited pieces of evidence in support of the Big Bang model. Hubble’s law is known to be the first observable basis for the expanding space paradigm, and today this law serves one of the few pieces of evidence attributed to support for the Big Bang Theory