Now do we know that the galaxies are moving away from one another?
Application of the Doppler effect to the light waves has helped us to know that the galaxies are moving away from each other. When the object moves away from us, the frequency of light emitted by it will decrease and shift towards the red end of the visible spectrum i.e. red shift, which indicates the recession of that object. It was the scientist E. Hubble who studied the light emitted by different galaxies and observed the red shift in the spectrum of light coming from far off galaxies. This has lead us to believe that the galaxies are moving away from one another.
