If the average density of the Universe is small compared with the critical density, the expansion of the Universe described by Hubble’s law proceeds with speeds that are nearly constant over time. (a) Prove that in this case the age of the Universe is given by the inverse of the Hubble constant. (b) Calculate 1/H and express it in years.

If the average density of the Universe is small compared with the critical density, the expansion of the Universe described by Hubble’s law proceeds with speeds that are nearly constant over time. (a) Prove that in this case the age of the Universe is given by the inverse of the Hubble constant. (b) Calculate 1/H and express it in years.