Test 2, 2019.5.15
Astronomy 123

Topic 3, History of the Universe
Topic 4, Observations and the Fate of the Universe Test 1, Test 2, Test 3, Test 4

Multiple Choice Key for Test 4:

C,C,A,C,C,D,A,E,A,C,E,E,(B,A--recent results),A,...--(>3,500, recent results)

History of the Universe

• How old is the Universe? How do we arrive at this age estimate? How old are the oldest stars in the galaxy? Is there a problem with this age for the oldest stars? Estimate the age of the Universe assuming that its rate of expansion is constant. Is this age an overestimate, underestimate, or just right for a universe which slows in its rate of expansion?
• What is the correct order for the radiation era, the matter era, and the dark energy era? When did the transitions from era to era occur? What is meant by radiation era, matter era, and dark energy era? In which era is the Universe (the current Universe)?
• What are the Planck, GUT, quark, lepton eras?
• When did the inflation take place? What are the four known forces in the current Universe? Describe how the forces that govern the Universe change as the Universe involves? What is meant by symmetry breaking? What is a phase transition? Give an everyday example of a phase transition. What is the relevance of a phase transition to our description of inflation.
• What problems of the Universe (first, what are they?) are explained by inflation?
• What is eternal inflation?
• Big Bang Nucleosynthesis. When were the chemical elements present in the Universe formed? Why were they not formed earlier? (What is the deuterium bottleneck?) What chemical elements were produced in the Big Bang? Why weren't elements like carbon, nitrogen, and oxygen produced in the Big Bang?
• What is Recombination? When did it occur? What does it have to do with the CMBR?
• What is meant by pair production? What is meant by annihilation? Physicaly, what is the meaning of E = mc²? How do these notions lead to conundrum of the the Matter/Anti-Matter Asymmetry? How do we estimate the size of the Matter/Anti-Matter Asymmetry? How do matter and anti-matter particles compare?
• What are virtual pairs? What is the Heisenberg Uncertainty Principle? How does the notion of the Heisenberg Uncertainty Principle lead to virtual pairs. What is tunneling? What is its significance in terms of nuclear reactions?
• Cosmological Constant. How do virtual pairs lead to a possible explantion for the Cosmological Constant? How does a matter particle differ from its anti-matter twin? We say that the Cosmological Constant corresponds to negative pressure. Explain this comment.

Fate of the Universe

• Describe how the following methods used to determine the ultimate fate of the Universe work:
  • Examination of the behavior of the Hubble Law at large z. How is the Hubble Law at large z determined? What standard candles are used for this exercise? What fate for the Universe is implied by these results?
  • Comparison of the models of the Universe to the CMBR. How did WMAP use the small fluctuations in the CMBR to determine the dark matter content of the Universe? What is the dipole anisotropy? What does the CMBR say about the viability of inflation as a model for the early expansion of the Universe?
• What is current best model for the Universe? What is the Universe composed of for the best model?
• How is the expansion rate of the Universe determined? What is the most difficult aspect in the determination of the expansion rate of the Universe? What is bootstrapping?
• How were observations of galaxy clusters and other structures used to detect Dark Matter? What is the significance of flat rotation curves? What fraction of the current Universe currently thought to be matter? What fraction of this is dark matter? What fracion is normal matter?
• What is dark energy? How do we know dark energy exists? Oh, by the way, how do we know dark matter exists? What do we mean by dark matter?
• Describe the evolution of the Universe starting from today to its ultimate fate. Be sure to describe how the appearance and make-up of the Universe changes as it evolves.
• Far into the future, if life somehow redevelops on the Earth, describe what the Universe will look like to an observer on the Earth. Would the three fundamental observational results about the Universe which drive the Big Bang Theory be found? If not, why not? What kind of cosmological model would an observer on the future Earth likely develop to describe the Universe? How would our current thinking about how the Universe evolves compare to that found by future observer? Would we conclude that the Cosmological Principle was valid? Why or why not.
• What is the Big Freeze? What is the Big Rip? What causes the Big Rip?