Estimate the age of the universe in seconds using the Hubble constantH0 = 70 km s–1 Mpc–1.

Sure, here's how you can estimate the age of the universe in seconds using the Hubble constant (H0 = 70 km s–1 Mpc–1):

1. First, we need to convert the Hubble constant from km/s/Mpc to s^-1. To do this, we need to know that 1 Mpc (megaparsec) is approximately equal to 3.09 x 10^19 km.

   So, H0 = 70 km/s/Mpc = 70 km / s / 3.09 x 10^19 km = 2.268 x 10^-18 s^-1.

2. The Hubble constant is an estimate of the rate of expansion of the universe. The inverse of the Hubble constant gives us an estimate of the age of the universe.

   So, Age of the universe = 1 / H0 = 1 / 2.268 x 10^-18 s^-1 = 4.41 x 10^17 seconds.

This is a rough estimate and assumes that the rate of expansion of the universe has been constant, which is not the case according to current cosmological models. But it gives us a general idea of the age of the universe in seconds.