Cosmology

Cosmology

1. Define cosmology and outline two of the important unanswered questions in this branch of astronomy.

2. How is the geometry of the Universe related to the mass of the Universe?

3. Describe the three possible geometries of the Universe and the fate of the Universe that each implies.

4. What is the Cosmological Principle?

5. What is gravitational lensing and how is it a consequence of Einstein's General Relativity?

6. What are gamma ray bursts and what evidence suggests they are not "local" but are at cosmological distances?

7. What are some of the suggested mechanisms for the large energies associated with gamma ray bursts?

The Early Universe

1. Why can the very early Universe be described as remarkably simple? What is the "cast of characters" in the Universe one millionth of a second after the big bang?

2. Outline the events that occurred during the first three minutes of our Universe's history.

3. For how long was the Universe radiation-dominated? What caused the change from a radiation-dominated to a matter dominated Universe? What caused the change from an opaque to a transparent Universe?

4. What is the Perfect Cosmological Principle and how does it differ from the Cosmological Principle?

5. How did the steady-state hypothesis reconcile the expansion of the Universe with the requirement that an unchanging Universe must have a constant density through time?

6. What evidence ruled out the steady-state hypothesis?

7. Describe the serendipity involved in the discovery of the Cosmic Background Radiation (CBR).

8. What is meant by the statement that the CBR has a temperature of 2.7 K? At the time the CBR was emitted, it was being emitted by a gas at 3000 K. Why is its peak in the radio portion of the spectrum rather than visible or infrared?

9. Why does the isotropy of the CBR present two problems for the standard big bang theory? How does the small fluctuations discovered by COBE help to solve one of these problems?

10. How does the inflationary big bang cure the horizon problem, the flatness problem, and the monopole problem?

11. Distinguish between the top-down theories and bottom-up theories of structure formation.