1. The Cosmological Constant:
a) Was first introduced by Edwin Hubble, to explain the expansion of the Universe.
b) Was first introduced by Albert Einstein, to prevent his models of the Universe from expanding or contracting.
c) Was first introduced by Maarten Schmidt, to explain why we don't see nearby quasars.
d) Was first introduced by Harlow Shapley, to explain the 3D distribution of globular clusters in space.
e) Was first introduced by Heinrich Wilhelm Olbers, to explain the expansion of the Universe.

2. The astronomical term `Lookback Time' refers to:
a) The age of the Milky Way.
b) The age of the Universe.
c) The time it took the light from an object to reach us.
d) The size of the local supercluster, in light years.
e) The distance in light years to the most distant galaxy ever seen.

3. A Universe with a `saddle' shape to its curvature is an:
a) open Universe.
b) closed Universe.
c) finite Universe.
d) Universe with a density greater than the critical density.
e) all of the above.

4. The cosmic microwave background radiation:
a) is radiation from a giant nearby supernova.
b) is microwave radiation from accelerated electrons in the plane of the Milky Way.
c) is perfectly uniform microwave radiation that fills the Universe: exactly the same strength radiation in all directions.
d) was discovered by accident by two engineers at Bell Telephone Laboratory.
e) All of the above.

5. If the Universe is infinite and is filled with galaxies, one might expect that in every direction one looked one would see a galaxy. Why is this not the case?
a) The `Great Wall' prevents light from distant galaxies from reaching us.
b) The Universe is not infinitely old.
c) The Universe is empty beyond the `Great Wall'.
d) The Universe is filled with dark matter, which blocks the light from distant galaxies.
e) The Big Bang destroyed most of the Universe.

6. What kind of observations have provided evidence for dark energy in the Universe?
a) observations of stellar parallax to nearby stars.
b) observations of Cepheid variables in the Andromeda Galaxy.
c) observations of the rotation curves of spiral galaxies.
d) observations of distant type I supernovae.
e) all of the above.

7. Which of the following pairs of particles are produced together in a single pair production reaction?
a) a proton and a neutron.
b) a proton and an electron.
c) an electron and a positron.
d) a neutron and an electron.
e) a positron and a proton.

8. The cosmic deuterium abundance provides information about:
a) The Hubble constant.
b) The total density of matter in the Universe.
c) The density of baryons in the Universe.
d) Whether the dark matter is Cold Dark Matter or Hot Dark Matter.
e) Whether life exists elsewhere in the Universe.

9. Olber's Paradox is about:
a) The numerical value of Hubble's constant.
b) Whether the `Andromeda Spiral Nebula' is inside or outside the Milky Way.
c) How much dark matter there is the Universe.
d) The nature of the dark energy.
e) The observable Universe.

10. Before the early 1960's, what was a popular competing theory to the Big Bang theory?
a) The Big Burst.
b) The Recombination Theory.
c) The Steady State Theory.
d) The Inflationary Universe Theory.
e) The Baryonic Theory.

11. What type of particle played an important role in primordial nucleosynthesis, but not in the nuclear reactions going on in the Sun?
a) free protons.
b) free neutrons.
c) free deuterium.
d) free ³He ions.
e) free ⁴He ions.

12. Which of the following is not baryonic matter?
a) neutrinos.
b) protons.
c) neutrons.
d) deuterium nuclei.
e) ³He nuclei.

13. Which of the following has been used to constrain the properties of the Universe?
a) computer models of the Universe.
b) measurements of deuterium in the Universe.
c) observations of SN Type I.
d) observations of the velocity dispersion of galaxies in clusters.
e) all of the above.

14. Albert Einstein:
a) Was the first person to show the Universe was expanding with time.
b) Introduced the cosmological constant.
c) Showed that quasars are more common at large distances from us, than nearby.
d) Invented the Inflationary Universe model.
e) Invented the Big Bang theory.

15. A closed Universe:
a) is finite.
b) is infinite.
c) has a density less than the critical density.
d) will continue expanding forever.
e) all of the above.

16. Who first detected the Cosmic Microwave Background?
a) Edwin Hubble.
b) Henrietta Leavitt.
c) Maarten Schmidt.
d) Carl Jansky.
e) Robert Wilson and Arno Penzias.

17. What is Arno Penzias best known for?
a) Detecting the Cosmic Microwave Background.
b) Discovering the expansion of the Universe.
c) Discovering quasar evolution.
d) Inventing the Inflationary Universe model.
e) Measuring the deuterium abundance in the Universe.

18. In primordial nucleosynthesis, what is the primary end product of the reactions?
a) deuterium.
b) ⁴He.
c) iron.
d) carbon.
e) uranium.

19. The period of recombination occurred how long after the Big Bang?
a) a billion years.
b) 400,000 years.
c) 15 minutes.
d) 1 minute.
e) 0.0001 second.

20. According to standard Big Bang theory, how long after the Big Bang did pair production of electrons and positrons end?
a) a billion years.
b) 400,000 years.
c) 15 minutes.
d) 1 minute.
e) 0.0001 second.

21. According to standard Big Bang theory, how long after the Big Bang did pair production of protons and anti-protons end?
a) a billion years.
b) 400,000 years.
c) 15 minutes.
d) 1 minute.
e) 0.0001 second.

22. How long after the Big Bang did galaxies start forming?
a) less than a billion years, but more than 400,000 years.
b) 400,000 years.
c) 15 minutes.
d) 1 minute.
e) 0.0001 second.

23. On which of the following solar system objects did scientists find evidence for Earth bacteria, which had traveled there on a spacecraft and survived for years?
a) Venus.
b) Mars.
c) The Moon.
d) Europa.
e) Mercury.

24. The best estimate we have for the baryonic density of the Universe comes from:
a) Observations of type I supernovae.
b) Measurements of the cosmic microwave background.
c) Measurements of the total mass of galaxy clusters.
d) Observations of the H-R diagrams of clusters.
e) Measurements of the primordial deuterium abundance.

25. Albert Einstein:
a) Discovered that the Universe was expanding with time.
b) Discovered that the Universe's expansion was accelerating with time.
c) Assumed the Universe was static, so he added the Cosmological Constant to his equations to produce a static Universe.
d) Calculated the age of the Universe.
e) Predicted the cosmic microwave background.

26. According to standard Big Bang theory, what event occurred about 400,000 years after the Big Bang?
a) The end of primordial nucleosynthesis.
b) The end of pair production of electrons and positrons.
c) The end of pair production of protons and anti-protons.
d) The formation of long-lived neutral atoms in the Universe.
e) A period of great inflation, where the Universe suddenly expanded by a huge amount in a very short amount of time.

27. According to the Inflationary Universe model, a period of great expansion of the Universe occurred very shortly after the Big Bang. According to this theory, this was caused by:
a) The end of primordial nucleosynthesis.
b) The end of pair production of electrons and positrons.
c) The end of pair production of protons and anti-protons.
d) The formation of long-lived neutral atoms in the Universe.
e) The separation of the strong force from the electroweak force.

28. If the Universe is infinite and filled with galaxies, why is the sky dark at night? This question is called:
a) Einstein's conjecture.
b) Hubble's law.
c) Olber's paradox.
d) Einstein's paradox.
e) The Steady State paradox.

29. According to the Inflationary Universe model, we live in a flat Universe, with a total (mass+energy) density equal to the critical density. According to recent observations and theory, which of the following dominates the total mass+energy in the Universe, contributing about 70% of the total?
a) baryonic visible matter.
b) baryonic dark matter.
c) non-baryonic dark matter.
d) dark energy.
e) none of the above.

30. The so-called `Grand Unified Theories' (GUTs) are able to unite three of the four forces of nature into a single force. Which of the four forces is not included in GUTs?
a) gravity.
b) electricity.
c) magnetism.
d) the strong force.
e) the weak force.

31. Baryonic matter is:
a) All matter that produces a gravitional force, whether or not it is visible.
b) Matter made out of the heavier chemical elements, such as carbon, oxygen, and nitrogen, but not including hydrogen and helium.
c) The dominant contribution to the total matter of galaxy clusters.
d) Matter made out of protons and neutrons.
e) Another term for dark matter.

32. Free neutrons are unstable; they will spontaneously decay into a proton, electron, and an anti-neutrino. What is the typical lifetime of a free neutron?
a) 10^-32 seconds.
b) 0.0001 seconds.
c) 15 minutes.
d) 400,000 years.
e) 13.7 billion years.

33. Which of the following theories is able to explain the `Horizon Problem' (the uniformity of the cosmic microwave background) and the `Flatness Problem' (why the observed density of the Universe is close to the critical density)?
a) The General Theory of Relativity.
b) Hubble's Law.
c) The Inflationary Universe Theory.
d) The Big Bang Theory.
e) The Steady State Theory.

34. In the 1953 Miller-Urey experiment, ammonia, methane, carbon dioxide, and water vapor reacted in the presence of an electrical spark to form:
a) simple bacteria.
b) amino acids.
c) amoeba.
d) uranium and plutonium.
e) all of the above.

35. Which of the following elements was created in large quantities by primordial nucleosynthesis?
a) carbon.
b) oxygen.
c) iron.
d) uranium.
e) helium.

36. Most of the photons of light in the cosmic microwave background radiation has been traveling through space unimpeded since:
a) The end of pair production in the early Universe.
b) The end of primordial nucleosynthesis in the early Universe.
c) The time of Recombination, when long-lived neutral atoms first formed in the early Universe.
d) About 15 minutes ago.
e) About 0.001 seconds ago.

37. If the baryonic matter in the Universe was the ONLY factor affecting the expansion and subsequent evolution of the Universe, what will be the ultimate fate of the Universe?
a) It will continue to expand forever.
b) It will eventually collapse back upon itself in a `Big Crunch'.
c) It will continue to expand, until at an infinite time its expansion velocity will be zero.
d) None of the above.
e) We do not yet have an estimate of the density of the baryonic matter in the Universe, so we don't have an answer to this question.

38. Most of the carbon presently observed in the Universe was created:
a) Within the first 0.0001 seconds after the Big Bang.
b) Within the first 1 minute after the Big Bang.
c) Within the first 15 minutes after the Big Bang.
d) Within the first 400,000 years after the Big Bang.
e) Between 400,000 years after the Big Bang and the present.

39. Within the first 0.0001 seconds after the Big Bang, most of the cosmic background radiation was:
a) microwaves.
b) long wavelength radio waves.
c) gamma rays.
d) optical light.
e) infrared light.

40. Which of the following provides constraints on cosmological models?
a) The H-R diagrams of star clusters in the Milky Way.
b) The amount of deuterium in the Universe.
c) Observations of distant type I supernovae.
d) The cosmic microwave background.
e) All of the above.

41. The so-called Dark Energy is:
a) Baryons.
b) Gamma rays.
c) Dark matter.
d) Positrons.
e) Scientists do not know.

42. The most distant galaxies seen so far have lookback times of about 13 billion years. This means:
a) They are 13 billion light years away.
b) They are now closer than 13 billion light years.
c) They are now further away than 13 billion light years.
d) They formed when the Universe was about 13 billion years old.
e) They formed when the Universe was about 1000 years old.

43. Which of the following is NOT ruled out as the major contributor to the dark matter in the Universe, based on studies of galaxy clusters and the amount of deuterium in the Universe?
a) planets like Jupiter.
b) white dwarfs.
c) brown dwarfs.
d) non-baryonic particles.
e) interstellar molecular hydrogen.

Answers: 1b, 2c, 3a, 4d, 5d, 6d, 7c, 8c, 9e, 10c, 11b, 12a, 13e, 14b, 15a, 16e, 17a, 18b, 19b, 20d, 21e, 22a, 23c, 24e, 25c, 26d, 27e, 28c, 29d, 30a, 31d, 32c, 33c, 34b, 35e, 36c, 37a, 38e, 39c, 40e, 41e, 42c, 43d.