Chapter 33, Problem 20Q

To determine

(a) To determine:

With time the expansion rate of the universe decreases, explain it.

Answer to Problem 20Q

Solution:

The initial energy from the Big Bang that causes the universe to expand would slow down because of the gravitational pull between all celestial bodies. This would expectedly cause a deceleration with time.

Explanation of Solution

The Big Bang model describes how for very high temperature and density the universe expands with time.It also gives explanation for the cosmic microwave background, large scale structure and abundance of light element.

To determine

(b) To determine:

According to a principle, universe will expand more than now. Explain it.

Answer to Problem 20Q

Solution:

Astronomers could use the redshift measurement from galaxies to determine if the rate of expansion of the universe is decreasing with time.

Explanation of Solution

Distance between the galaxies are measured using the red shift. If the red shift between the galaxies is more, the distance between the galaxies is more. High energy wavelength are emitted by some very distant objects.