Estimate the critical density of the universe if the Hubble's constant was 50 km/s/Mpc.

• The minimum density that is required to stop the expansion of the universe is defined as the critical density. A universe with its density at critical density is said to be flat.

• Critical density is given by,

$\boxed{{\mathbf{\rho }}_{\mathbf{\text{c}}}\mathbf{=}\frac{\mathbf{3}{\mathbf{H}}^{\mathbf{2}}}{\mathbf{8}\mathbf{\pi }\mathbf{G}}}$$\boxed{\frac{\mathbf{}}{}}$

Here H is the Hubble constant and G is Newton’s gravitational constant.