The Evolving Universe

Question 1

How can we use red shift as a distance indicator?

Answer 1

z = v/c, so v/cz, so d=cz/H0

Question 2

What does Hubbles law imply?

Answer 2

That there is uniform centre-less expansion.

Question 3

How do you find the age of the universe?

Answer 3

Use Hubbles law v = H0d. and d = v dt. If expansion is constant, dt = d/V = 1/H0 (reciprocal of Hubble constant).

Question 4

What is the approximate age of the Universe?

Answer 4

13.6*10^9 years

Question 5

What is the evidence for the big bang?

Answer 5

• Nucleosynthesis of the primordial elements

- Expected presence of microwave background that represents the stretched radiation from the young Universe

Question 6

What is CMBR?

Answer 6

Cosmic Microwave Background Radiation: was detected with a peak wavelength of about 1mm, and spectrum is a black boy with T = 2.7K

Question 7

What is Nucleosynthesis and when did it happen?

Answer 7

Abundance of the elements - was set in the first ten minutes when the plasma cooled and light elements could form

Question 8

What is the evidence against the big bang?

Answer 8

On a graph of distance modulus against red shift, distant supernovae appear to be further away than expected, meaning that the Universe is not expanding uniformly. must be a repelling force to cause acceleration.

Question 9

How can we use CMB to measure the curvature of the Universe?

Answer 9

• If universe if close, light rays bend towards each other and we see larger hot spots
• If universe is flat, light rays stay the same so we see the actual size of hot spots
• If Universe is open, light rays bend away from each other, so the hot spots appear to be smaller

Question 10

What is dark energy?

Answer 10

The energy which nobody knows anything about but causes the expansion acceleration.

Question 11

What are the percentages of things in the univers?

Answer 11

• Ordinary matter: 4.9%
• Dark matter: 26.8%
• Dark energy: 68.3%