Week 7

1. What would cause a galaxy to redirect the light of a galaxy behind it?
   a. A magnetic field from a supermassive black hole.
   b. The gravity of the intervening matter.
   c. The dark energy in the halo of the foreground galaxy.
   d. The globular clusters.
   

2. What will become of the universe in the future if the average density of mass in the Universe is higher than the critical density?
   a. collapse.
   b. expand forever.
   c. stop expanding but not collapse.
   d. undergo rapid inflation.
   

3. The light from galaxies outside of our Local Group is red-shifted. Why?
   a. Distant galaxies are moving at the speed of light.
   b. Distant galaxies are receding because space is expanding.
   c. Distant galaxies have higher energy output than expected.
   d. Distant galaxies are all moving towards our Local Group.
   

4. Which are facts that the Big Bang theory attempts to explain?
   a. The Cosmic background radiation.
   b. The proportions of the lighter elements.
   c. The evolution of the architecture of galaxies over time.
   d. All of the above.

5. What is the meaning of Hubble's Constant?
   a. it describes the expansion rate of the Universe, and inversely the age of the Universe.
   b. it describes the temperature fluctuations in the Cosmic Microwave Background.
   c. it describes the minimum density needed for gravity to overcome the expansion of the Universe and cause it to collapse.
   d. it describes the decoupling of photons from matter about 300,000 years after the Big Bang.
   

6. What does the apparent expansion of the universe tell us?
   a. The Universe has contracted and expanded many times before the current phase.
   b. Our galaxy is in the middle of the universe.
   c. Our universe was once smaller and started expanding at some time in the past.
   d. Our universe has been expanding forever.
   

7. What event might end with a proton and an antiproton being created?
   a. the energy of two colliding photons is greater than a proton/anti-proton pair.
   b. electron and positron pairs are combined with a force greater than a proton/anti-proton pair.
   c. a mass greater than a proton/anti-proton pair inside a black hole is destroyed.
   d. mass greater than a proton/anti-proton pair escape from the event horizon of a black hole.
   

8. Why do we appear to be in the center of the Universe?
   a. Space is expanding, carrying all galaxies away from each other.
   b. Space is curved, distorting the light coming from objects near us.
   c. We are in the center of the Universe.
   d. Hubble's constant is too small to measure.
   

9. What are quasars?
   a. Objects high above the galactic plane.
   b. Objects within the galactic plane.
   c. Objects with very high red-shifts.
   d. Objects in the cores of nearby galaxies.
   

10. Which of the following is a characteristic of active galaxies?
    a. Their energy output is steady in time.
    b. They generally exhibit no signs of explosive activity.
    c. They are generally less luminous than normal galaxies.
    d. Their energy emission cannot be explained as the accumulated emission of their stars.
    

11. The cosmological model known as the Big Bang model is essentially this.
    a. Heavy elements formed in the early universe as a result of a brief period of rapid fusion.
    b. A massive explosion created all of the heavy elements in the early universe.
    c. At one time the universe was very small but it expanded, and is continuing to expand today.
    d. Dark energy is causing the universe to clump together and eventually it will collapse.
    

12. Which of these statements is consistent with the Theory of General Relativity?
    a. The large-scale density of mass tells us whether new matter is constantly forming, thereby producing a steady-state.
    b. The large-scale density of mass determines the attraction between galaxy clusters, which counters the expansion rate of the universe.
    c. The large-scale density of mass tells us the critical value of dark matter which will causes the Universe to be static.
    d. The large-scale density of mass determines the rate of formation of black holes which will eventually collapse the Universe.
    

13. What is the most common form of matter?
    a. dark matter.
    b. neutrinos
    c. quarks.
    d. protons
    

14. What is the basic conclusion of Einstein's theory of Special Relativity?
    a.  Time is not absolute.
    b.  Time is absolute.
    c.  Time is not real.
    d.  Time is accelerating.
    

15. What does it mean if we see small objects at extreme distances?
    a. They are very energetic.
    b. They are actually quite large.
    c. They are actually quite close.
    d. They are an illusion.
    

16. How do we know that the bright spots in active galactic nuclei are coming from star-sized objects?
    a. The emission spectra resembles stars.
    b. The energy is in amounts consistent with stars.
    c. We can measure the width.
    d. The brightness changes very quickly.
    

17. The Light coming from every galaxy outside of our local group is redshifted. What is our simplist reason for this?
    a. The universe is expanding.
    b. We are precisely at the center of the Universe.
    c. The universe is static and unchanging.
    d. There should be an equal number of galaxies that are blueshifted out there somewhere.
    

18. Which observation is strong evidence for the Big Bang model?
    a. Einstein's General Relativity Theory.
    b. Einstein's Special Relativity Theroy.
    c. Redshift measurements of galaxies indicate an overall expansion of the Universe.
    d. Active galaxies are undergoing close interaction with other galaxies.
    

19. How do astronomers calculate the distance to the farthest galaxies?
    a. Tully-Fisher correlation.
    b. Geometric Parallax.
    c. Redshift.
    d. Cepheid variable stars.
    

20. Which of these is a simple explanation for the redshift of distant galaxies?
    a. a primeval explosion.
    b. the speed of light is changing.
    c. fluxuations of the CMBR.
    d. space is expanding.