34.1 Exercise 26

(a) What Hubble constant corresponds to an approximate age of the universe of $\text{10}^{\text{10}}$ y? To get an approximate value, assume the expansion rate is constant and calculate the speed at which two galaxies must move apart to be separated by 1 Mly (present average galactic separation) in a time of $\text{10}^{\text{10}}$ y. (b) Similarly, what Hubble constant corresponds to a universe approximately $2 \times \text{10}^{\text{10}}$-y old?