Chapter 34, Problem 30PE

To get an idea of how empty deep spam is on the average, perform the following calculations:

(a) Find the volume our Sun would occupy if it had an average density equal to the critical density of thought necessary to halt the expansion of the universe.

(b) Find the radius of a sphere of this volume in light years.

(c) What would this radius be if the density were that of luminous matter, which is approximately 5% that of the critical density?

(d) Compare the radius found in part (c) with me 4-ly average separation of stars in the aims of the Milky Way.