PHYS146 Exam 3 Information

Last revised 1999/05/10

The Third Exam covers

• Hawking, Chapters 2, 8, 11
• Notes on
  • General Relativity
  • Expansion and ages
  • Dark matter

1. What is the ultimate fate of stars?
2. Why is the uniformity of the 3K cosmic-background radiation a problem?
3. What is the anthropic principle?
4. How would inflation solve the uniformity problem? Is there any other solution?
5. Why would an inflationary expansion occur?
6. If the velocites of galaxies are given by H₀ x distance, what is the simplest estimate of the age of the universe?
7. Why is the simplest estimate of the age of the universe not exact? Under what circumstances would the estimate be too long? Too short?
8. Is there complete agreement about the value of Hubble's constant?
9. What parameters' values have to be guessed in order to relate Hubble's constant to the age of the universe?
10. Where does the theoretically preferred value of the mass density of the universe come from?
11. Why might we want to choose 0 for the value of the cosmological constant? Why would we choose a nonzero value?
12. How is the age of a globular cluster determined?
13. What is the problem with the estimated ages of the globular clusters? Is this a serious problem?
14. Is the expansion of the Universe uniform in time?
15. What do supernovae have to do with the expansion of the Universe?
16. Do we know what makes up all of the matter in the Universe?
17. What might Dark Matter be made of?
18. How do we detect Dark Matter?
19. How much of the mass of the Universe is dark matter?
20. Is the Universe finite in size?
21. Will the Universe expand forever?
22. What are the weak and strong equivalence principles? Are there any differences between the implications of the two? If so, give at least one additional implication of the strong equivalence principle.
23. What is a local inertial frame?
24. How would an observer determine that he is in a local inertial frame?
25. What requires that a local inertial frame cover a small region?
26. How is gravitation "explained" in General Relativity?
27. Name 3 experimental verifications of General Relativity [Hawking Chapter 2 will help].
28. Does light lose energy moving away from a massive body? If so, what property of light shows that the energy has been lost?
29. Are clocks affected by gravitational fields?
30. How do you determine that there should be a gravitational red shift? Explain.
31. Does General Relativity affect the 1/r² dependence of the brightness of a point source on its distance? If so, how?
32. Does General Relativity affect the angular size of an object as a function of its distance? If so, how?
33. Is the distance-dependence of the angular size and the total brightness of an object the same. If not, when and why not?
34. What is the effect of the cosmological constant?
35. Why do theorists like to formulate the behavior of particles in terms of strings instead of points?
36. Are strings formulated in the observable 4 dimensions alone? If not, how is the nonobservation of additional dimensions explained?
37. Are strings always formulated in terms of a single number of dimensions?
38. In string theories, how are quarks and leptons generated?
39. What is supersymmetry? What is the experimental evidence supporting its existance?
40. Do physical theories always come directly from experimental evidence? Give example(s) supporting your answer.