Question

ddoes hubble constant is depend upon time?

Answer 1

The Hubble constant does depend upon time. The units of the hubble constant (H) are identical to inverse time. In other words, \[t =1/H\] where t is the time since expansion began. Using a value of 72 km/(sec.Mpc) for today's Hubble constant, we obtain a value of t (after converting to same units) = 13.6 billion years. So 6.8 billion years ago, the hubble constant would have been twice as large, about 144 km/(sec.Mpc).