Our universe is always expanding. The rate at which galaxies are receding from each other is given by Hubble’s law (discovered in 1929 by E. Hubble). The law states that the rate of separation of two galaxies is directly proportional to their separation. It means relative speed of separation of two galaxies, presently at separation r is given by v = Hr
H is a constant known as Hubble’s parameter. Currently accepted value of H is `2.32 ×x 10 ^(–18) s^(–1)`
(a) Express the value of H in unit of
`(Km.s^(-1))/("Mega light year")`
(b) Find time required for separation between two galaxies to change from r to 2r.
