Critical Density: H0=70km/s.MPC, Fate of Universe

[b_o3]

hello, can anyone help me with this problem please:

For H0=70 km/ S . MPC , what is the critical density (p0) for the universe in gm/cm^3? . if the average density of the universe is 5 * 10 ^ -28 gm/cm^3 , what is the fate of the universe.

thanks ,

 

[Dick]

You don't know ANY relevant equations? You need to make a start at a solution and prove you are stuck before anyone can help.

 

[m2003]

Hello,

The critical density, p0, for the universe can be calculated using the formula p0 = 3H0^2/8πG, where H0 is the Hubble constant and G is the gravitational constant. Plugging in H0 = 70 km/s.MPC (where MPC stands for megaparsec, a unit of distance used in cosmology) and converting to proper units, we get p0 = 1.878 x 10^-29 gm/cm^3.

Comparing this to the average density of the universe, 5 x 10^-28 gm/cm^3, we can see that the average density is much lower than the critical density. This means that the universe is currently open, meaning that it will continue to expand forever.

If the average density were to somehow increase to match the critical density, the universe would be flat and would continue to expand at a constant rate. However, if the average density were to decrease even further, the universe would be open and would expand at an accelerating rate.

In summary, based on the given information, it seems that the fate of the universe is to continue expanding forever. However, this is subject to change if the average density were to change significantly in the future. I hope this helps!