Prof. Muni Mahendra Kumar
We have already seen that according to Hubble’s law, the velocities of receding galaxies are proportional to their distances. If we trace the motion of galaxies backward in time, assuming that each galaxy always had the velocity it has now, (which may not be true), then Hubble’s result implies that 2,000 million years (this figure is known as Hubble’s constant) ago, all the galaxies were crowded on top of one another.[1] The observations made after the above determination necessitates revision of the above number, which is now accepted as 10,000 million years.[2]
Thus, if the Hubble’s constant is accepted, it can be said that the universe began:
10,000,000,000 (ten-billion) years ago.
