Test 2, 2017.5.27
Astronomy 123

Topic 6, History of the Universe (CM, Chapters 26 and 27), Observations and the Fate of the Universe (CM, Chapters 24-26)

Test 1, Test 2

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?
• 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?
• Big Bang Nucleosynthesis. When were the chemical elements present in the Universe formed? Why were they not formed earlier? 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 the significance of the detection of deuterium?
• 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?
• What are virtual pairs? What is the Heisenberg Uncertainty Principle? How does the notion of the Heisenberg Uncertainty Principle lead to virtual pairs.
• 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.

Weighing the Universe and Determining the Expansion Rate for 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?
• How were observations of galaxy clusters and other structures used to detect 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.
• Describe black holes. What is the fundamental property for an object which makes it a black hole? What is the event horizon? What is meant by singularity? What is Hawking radiation?
• What is the Big Freeze? What is the Big Rip? What causes the Big Rip?

Life in the Universe: Drake Equation, Fermi Paradox, & SETI

• What is the Drake Equation? What are the parts which comprise the Drake Equation? How well-determined are the parts to the Drake Equation? What are the most well-determined parts of the Drake Equation? The least well-determined? How well-determined is the overall solution to the Drake Equation? What parts of the Drake Equation can be determined from astronomical observation? What is likely to be the most well-determined term in the Drake Equation? What is the Habitable Zone? Can there be two Habitable Zones? What determines the size of the Habitable Zone?
• Roughly how many extra-Solar planets have been discovered since 1995? How were most of the planets discovered? What is Kepler?
• How many extraterrestrial civilizations are there in our Galaxy based on the Drake Equation? Why are the results so uncertain?
• Describe the Gaia Hypothesis. Is the Gaia Hypothesis sensible? (Is there a mechanism which allows life on the Earth to play a role in the development of conditions suitable for life?)
• Describe the Faint Young Sun Problem. What is meant by equilibrium temperature? What is thought to be the solution for the Faint Young Sun Problem?
• Compare the evolution of the atmospheres of Venus, Earth, and Mars. Why did Venus and Mars turn out so differently from the Earth?
• Mars, today, has a hostile environment for life as we know it. People suggest that in the past, things may have been different. What evidence and arguments do people propose to support this conjecture?
• Water plays a key role in our thinking about the development of life. On which planets (objects) have we discovered water? What key observations suggest that we have found water on these objects? On which objects have we perhaps discovered suitable replacements for water?
• On what bodies in our Solar System have we searched for life?
• What is meant by LAWKI? Is this a sensible guide to use when searching for extra-Terrestrial life?
• Describe the Viking biology experiments. Describe the results of the Viking Biology experiments. What is the current consensus as to whether life was found on Mars by the Viking landers? What are the issues to be addressed?
• What is ALH84001? Cite the evidence found from study of ALH84001 which suggests life may have existed on Mars in the past. How solid is this evidence? What is a good next step for the follow-up of the ALH84001 study?
• Titan: What is Titan? What makes Titan an interesting target for a search for extra-Terrestrial life? The conditions on Titan are such that methane is near its Triple Point. What does this mean and why is it interesting from an extra-Terrestrial life standpoint? Cite evidence that Titan may harbor extra-Terrestrial life. Titan may show that there are two habitable zones in planetary systems. Explain this statement.