Answer:
Hubble's Law is the observation in physical cosmology that galaxies are moving away from the Earth at speeds proportional to their distance.
Step-by-step explanation:
In physics, a redshift is an increase in the wavelength and a corresponding decrease in the frequency and photon energy of electromagnetic radiation (e.g., light). The velocity of the galaxies has been determined by their redshift, a shift of the light they emit toward the red end of the spectrum. Hubble compared the distances to galaxies to their redshift and found a linear relationship. He interpreted the redshift as being caused by the receding velocity of the galaxies.