Space Physics and Astronomy - SS1 Physics Past Questions and Answers - page 3

Hubble's Law states that the velocity at which a galaxy is moving away from us is proportional to its distance. This implies that the universe is expanding, with galaxies moving away from each other. Hubble's Law provides evidence for the Big Bang theory, suggesting that the universe originated from a single point and has been expanding ever since. It also helps determine the rate of expansion, known as the Hubble constant. Understanding Hubble's Law is crucial for unravelling the dynamics and evolution of the universe.

Observational evidence supporting Hubble's Law and the expanding universe comes from the redshift of distant galaxies. When light from a galaxy is observed, its wavelength appears stretched, shifting towards longer wavelengths. This redshift indicates that the galaxy is moving away from us. Moreover, the degree of redshift is directly proportional to the galaxy's distance, as stated by Hubble's Law. This consistent relationship between redshift and distance provides strong empirical evidence for the expanding universe and validates Hubble's Law.