Test 3, 7 december 2011
Astronomy 123

Material: Topic 4, Active Galactic Nuclei (Chapters 24 & 25), Topic 5, World Views of the Universe (Chapters 26), Topic 6, History of the Universe (Chapters 26 and 27), Observations and the Fate of the Universe (Chapters 24-26)

Active Galactic Nuclei (AGNs)

• List two major differences between normal galaxies and active galactic nuclei. What were the most difficult properties of AGNs which needed to be explained by early researchers? What is the commonly accepted model for the energy engines of AGNs?
• Explain how the rapid variability is used to determine the maximum size of the emitting regions of AGNs.
• List and describe the major classes of Active Galactic Nuclei (AGNs). AGNs are thought to be represent phases in the evolution of normal galaxies. Descirbe evidence that supports this suggestion.
• Describe the evidence and arguments which suggest that the Universe contains supermassive Black Holes. How are supermassive Black Holes thought to be produced? Are supermassive black holes found only in AGNs?
• How efficient are black holes as energy engines? What fuels the black holes found in AGNs? What is the radius of 1 billion Solar mass black hole? Desribe the relationship between supermassive black holes and the masses of the bulges of the galaxies in which they are found. What is the significance of this relationship?

Models for the Universe

• Olbers's Paradox concerns the darkness of the night sky. Explain the nature of the paradox, that is, state the assumptions used, and outline the argument which leads to the conundrum. Explain how the Big Bang theory leads to the resolution of Olbers's paradox.
• What primary assumption underlies Friedman's models for the Universe? List Friedman's models for the Universe. Describe a test that allows us to choose the appropriate Friedman model for the Universe.
• In terms of spacetime, describe each of Friedman's models for the Universe. In what type of Friedman universe are we thought to live? Which universe is a closed universe (and what does this mean)? Which universe is an open universe (and what does this mean)?
• How can we distinguish open, closed, and flat universes? Describe the tests and the results of the tests described in class. Describe the behavior of parallel lines, triangles in the different Friedman models.
• Interpret and explain the Hubble Law in the context of an expanding Universe. Describe cosmological redshift. How does the cosmological redshift fit in with the Hubble Law?
• What is the Horizon Problem? What is the Flatness Problem? What is the Matter/Anti-Matter Asymmetry Problem? How does inflation address each of these problems?
• Carefully describe Inflation and describe the mysteries of the Universe that Inflation solves and explain how Inflation solves the problems.
• What are the four known forces of the current Universe? Have there always been only four distinct forces (four distinct ways in which things interact) in the Universe? If not, how has the situation evolved?
• What forces play dominant roles in the evolution of the Universe? How does the changing number of forces as the Universe evolves lead to inflation?

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?
• Describe how the Universe evolved starting from the Planck Era (what is meant by the Planck Era) to the GUTs to the Quark Era to Nuclear (Nucleosynthesis) Era and to the formation of the CMBR.
• What is the Compton wavelength? What defines the Planck Era? How long did the Planck era last? Why did the Planck era end?
• 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 meant by symmetry breaking? What were the various symmetry breakings which occurred in the evolution of the Universe? What are GUTs? What is the Theory of Everything?
• What are quarks, gluons, and baryons? Why dd the Quark era end? When did pair production of baryons end?
• 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:
  • Comparison of the mass of the Universe to the escape speed of the Universe. What is the result of these studies? How does it compare to the following two studies?
  • 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 is the fate of the Universe 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 dopole anisotropy? What does the CMBR say about the efficacy 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?
• Describe the methods used to determine the mass (in galaxies, binary galaxies, clusters of galaxies, from peculiar motions, from gravitational lensing) of the Universe. How much mass (in terms of the critical density) is found in these studies? How are these results reconsiled with the fact that there is strong evidence (from other methods) which imply that the Universe is flat, that is, the Universe has the critical density?
• 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 the extragalactic distance ladder? What is the Tully-Fisher method (how does it work)? How do Cepheids fit into the scheme? What are other ways to determine distances of distant objects? How do TYpe Ia SN fit into the extragalactic distance ladder?
• Describe how objects cluster in the Universe. Describe the properties of clusters of galaxies (such as Virgo and Coma). Why are there no spirals found near the centers of rich clusters of galaxies? What are cD galaxies? Why are supergiant Elliptical galaxies often times found near the centers of rich clusters of galaxies? How were observations of galaxy clusters used to detect Dark Matter? Who was the first astronomer to suggest the existence of Dark Matter? (What is meant by Dark Matter?)
• What are voids, filaments, and the Sloan Great Wall? How were these features detected? Does the observed structure in the Universe rule out the Cosmological Principle as a viable asuumption concerning the nature of the Universe? Why or why not. Is the structure observed in the Universe consistent with the CMBR observations?

Test 3, September 2, 2010
Astronomy 123
Summer 2010

Material: Topic 6, History of the Universe (Chapter 26 & 27), Topic 7, Ultimate Fate of the Universe (Chapters 24-26), Topic 8, Life in the Universe (Chapter 28)

Details:

Weighing the Universe and Determining the Expansion Rate for the Universe

• Describe the methods used to determine the mass (in galaxies, binary galaxies, clusters of galaxies, from peculiar motions, from gravitational lensing) of the Universe. How much mass (in terms of the critical density) is found in these studies? How are these results reconsiled with the fact that there is strong evidence (from other methods) which imply that the Universe is flat, that is, the Universe has the critical density?
• 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 the extragalactic distance ladder? What is the Tully-Fisher method (how does it work)? How do Cepheids fit into the scheme? What are other ways to determine distances of distant objects? How do TYpe Ia SN fit into the extragalactic distance ladder?
• Describe how objects cluster in the Universe. Describe the properties of clusters of galaxies (such as Virgo and Coma). Why are there no spirals found near the centers of rich clusters of galaxies? What are cD galaxies? Why are supergiant Elliptical galaxies often times found near the centers of rich clusters of galaxies? How were observations of galaxy clusters used to detect Dark Matter? Who was the first astronomer to suggest the existence of Dark Matter? (What is meant by Dark Matter?)
• What are voids, filaments, and the Sloan Great Wall? How were these features detected? Does the observed structure in the Universe rule out the Cosmological Principle as a viable asuumption concerning the nature of the Universe? Why or why not. Is the structure observed in the Universe consistent with the CMBR observations?

Models for the Universe

• Cite the primary pieces of evidence which drive the Big Bang Theory and the notion of Inflation. Also, carefully describe Inflation and describe the mysteries of the Universe which Inflation solves.
• Describe the Friedman models for the Universe. What assumption did Friedman make when finding his models for the Universe? Was this assumption valid?
• What is meant by positive, negative, and zero curvature? In which type of universe are we though to live? Which universe is a closed universe (and what does this mean)? Which universe is an open universe (and what does this mean)? That is meant by topology?
• How can we distinguish open, closed, and flat universes? Describe the tests and the results of the tests described in this portion of class.
• What is meant by cosmological redshift? Describe cosmological redshift. How does the cosmological redshift fit in with the Hubble Law? What is meant by scale factor [R(t)]? How does the scale factor behave for each type of Friedman universe?
• What are the four known forces of the current Universe? Have there always been only four distinct forces (four distinct ways in which things interact) in the Universe? What forces play dominant roles in the evolution of the Universe? How does the changing number of forces as the Universe evolves lead to inflation? What are GUTs?
• What is the Cosmological Constant? What is the Cosmological Constant Problem? What is the Horizon Problem? What is the Flatness Problem? What is the Matter/Anti-Matter Asymmetry Problem? Describe proposed solutions for these Problems.

History of the Universe

• How old is the Universe? How is this age arrived at? How old are the oldest stars in the Universe? 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?
• Describe how the Universe evolved starting from the Planck Era (what is meant by the Planck Era) to the formation of the CMBR. What is the Compton wavelength? How long did the Planck era last? Why did the Planck era end? How much matter was contained in the Universe at its birth? When were the elements present in the Universe formed? (What is meant by Big Bang Nucleosynthesis?) What elements were produced in the Big Bang? What is the significance of the detection of dueterium? Where did the principal elements which make the Earth and you come from? What is meant by symmetry breaking? What are GUTs? What is the Epoch of Recombination? When did it occur? What does it have to do with the CMBR?
• What is meant by pair production? annihilation? What is the meaning of E = mc²? What are virtual pairs? What is the Heisenberg Uncertainty Principle? What is the interplay of the Heisenberg Uncertainty Principle and virtual pairs (and how do virtual pairs lead to a possible explantion for the Cosmological Constant)? How does a matter particle differ from its anti-matter twin?
• Describe how the following methods used to determine the ultimate fate of the Universe work:
  • Comparison of the mass of the Universe to the escape speed of the Universe. What is the result of these studies? How does it compare to the following two studies?
  • 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 is the fate of the Universe 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 dopole anisotropy?
• What is current best model for the Universe? What is the Universe composed of for the best model?

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

• What is the Drake Equation? How well-determined is the solution to the Drake Equation? What parts of the Drake Equation can be determined from observation? What is likely to be the most well-determined term in the Drake Equation? What is the Habitable Zone? What determines the size of the Habitable Zone? What is meant by hot Jupiters? Roughly how many extra-Solar planets have been discovered since 1995? Which parts of the Drake Equation will be difficult to determine from observation? How many extraterrestrial civilizations are there in our Galaxy based on the Drake Equation? Why are the results so uncertain?
• What is the Fermi Paradox? That is, give the gist of the Fermi Paradox. How solid are the implications forced upon us by the Fermi Paradox? How likely is galactic exploration? How long would it take us to travel to our nearest neighbors in space? Are we trying to travel to other stellar systems? Are such trips feasible? What are von Neumann machines? How long would it take for a civilization, if it was so inclined, to explore the Galaxy?
• What is LAWKI? Is it a useful driving principle or is it a hinderance? What are SETI and CETI? Describe the Arecibo message to M13? How was it sent and how was it to be interpreted? What are the problems in formulating our attempts to communicate with extraterrestrials? Do we want to communicate with extraterrestrials? Do you think the Voyager plaques (and the earlier Pioneer plaques) are useful? Why or why not.
• What is time dilation? What is the Twin Paradox? How could utilizing the effects of time dilation aid in our exploration of the Galaxy?