Question

8. a) Let’s say one galaxy is 4 Mpc away from us and another is 16 Mpc away. If the nearer one moves 1 Mpc, how far will the more distant galaxy move in the same amount of time? b) How far away will each of the galaxies in part A be after that amount of time has passed?

9. How would a higher value for the Hubble constant affect the calculation of the age of the universe? A lower value?

10. If the value of the Hubble constant were 50 km/s/Mpc, what would be the farthest distance away at which we could see an object? Explain your answer. Is it possible that there are objects farther away that we cannot see? Explain your answer.

Answer 1

Solution:

Part 8 (i):

Galaxy A= 4Mpc

Galaxy B= 16Mppc

Nearer one moving 1Mpc

Now, Using Hubble Constant to be 70 km/sec per Mpc as its value varies between 65 to 75 km/s per Mpc

So, H= 70 = 4Mpc/1Mpc = 16Mpc/z

Now, Z= ... distance moved by a galaxy at 16Mpc

Part 9:

As (Hubble Constant) is a measure of the acceleration of expansion. Now,

and

From these two, taking higher value of we could calculate the age of the universe as being younger

Now, taking lower value of it would not be possible.