1. Copyright © 2010 Pearson Education, Inc. Test 4 Review Clicker Question Chs 13,14,15,16,&17

2. Copyright © 2010 Pearson Education, Inc. a) matter spiraling into a large black hole. b) the collision of neutron stars in a binary system. c) variations in the magnetic fields of a pulsar. d) repeated nova explosions. e) All of the above are possible. Question 13-1 One possible explanation for a gamma-ray burster is

3. Copyright © 2010 Pearson Education, Inc. a) matter spiraling into a large black hole. b) the collision of neutron stars in a binary system. c) variations in the magnetic fields of a pulsar. d) repeated nova explosions. e) All of the above are possible. Question 13-1 One possible explanation for a gamma-ray burster is Gamma-ray bursts vary in length, and the coalescence of two neutron stars seems to account for short bursts.

4. Copyright © 2010 Pearson Education, Inc. Question 13-2 Cygnus X-1 is a) NASA’s latest X-ray orbiting telescope. b) a millisecond pulsar with three planets. c) the strongest X-ray eclipsing binary system. d) a likely black hole binary star system. e) the first gamma-ray burster spotted in X rays.

5. Copyright © 2010 Pearson Education, Inc. Question 13-2 Cygnus X-1 is Cygnus X-1 is an X-ray source with one visible star orbited by an unseen companion of at least 10 solar masses, and very rapid changes in the signal indicating a small source. a) NASA’s latest X-ray orbiting telescope. b) a millisecond pulsar with three planets. c) the strongest X-ray eclipsing binary system. d) a likely black hole binary star system. e) the first gamma-ray burster spotted in X rays.

6. Copyright © 2010 Pearson Education, Inc. a) a beam of light. b) a massive object. c) neutrinos. d) antimatter. e) All of the above are correct. Question 13-3 The force of gravity can pull on

7. Copyright © 2010 Pearson Education, Inc. a) a beam of light. b) a massive object. c) neutrinos. d) antimatter. e) All of the above are correct. Question 13-3 The force of gravity can pull on Gravity is described by general relativity as a bending of space, and all particles, including photons, move through warped space along curved paths.

8. Copyright © 2010 Pearson Education, Inc. a) Earth’s orbit would not change. b) Earth would be pulled into the black hole. c) X rays would destroy Earth. d) Earth would be torn apart from the tidal force. e) life would be unchanged. Question 13-4 If the sun was replaced by a one-solar-mass black hole

9. Copyright © 2010 Pearson Education, Inc. a) Earth’s orbit would not change. b) Earth would be pulled into the black hole. c) X rays would destroy Earth. d) Earth would be torn apart from the tidal force. e) life would be unchanged. Question 13-4 If the sun was replaced by a one-solar-mass black hole The force of gravity depends only on mass and distance, not the type of matter, or its size.

10. Copyright © 2010 Pearson Education, Inc. a) is the point where X rays emerge. b) is the physical surface of the hole. c) defines the outer edge of an accretion disk. d) is measured by the Schwarzschild radius. e) extends for millions of miles into space. Question 13-5 The event horizon of a black hole

11. Copyright © 2010 Pearson Education, Inc. a) is the point where X rays emerge. b) is the physical surface of the hole. c) defines the outer edge of an accretion disk. d) is measured by the Schwarzschild radius. e) extends for millions of miles into space. Question 13-5 The event horizon of a black hole The event horizon is the surface of an imaginary sphere around a collapsed object inside of which nothing, including light, can escape.

12. Copyright © 2010 Pearson Education, Inc. a) supernova remnants. b) white dwarf stars in the spiral arms. c) red giant variable stars in globular clusters. d) bright O and B stars in open clusters. e) X-ray sources. Question 14-1 The location of the galactic center was identified using

13. Copyright © 2010 Pearson Education, Inc. a) supernova remnants. b) white dwarf stars in the spiral arms. c) red giant variable stars in globular clusters. d) bright O and B stars in open clusters. e) X-ray sources. Question 14-1 The location of the galactic center was identified using Harlow Shapley used pulsating RR- Lyrae variables as distance indicators to the globular clusters. He then deduced the distance and direction of the Milky Way’s center.

14. Copyright © 2010 Pearson Education, Inc. a) about 30 Kpc from the center in the halo. b) 30,000 light-years from the center in a globular cluster. c) at the outer edge of the galactic disk, in the plane. d) about halfway from the center, in the spiral arms. e) in the bulge, near the Orion arm. Question 14-2 Our Sun is located in the Milky Way Galaxy

15. Copyright © 2010 Pearson Education, Inc. Question 14-2 Our Sun is located in the Milky Way Galaxy The Sun orbits the center of the Galaxy within the disk, taking about 225 million years to complete one orbit. a) about 30 Kpc from the center in the halo. b) 30,000 light-years from the center in a globular cluster. c) at the outer edge of the galactic disk, in the plane. d) about halfway from the center, in the spiral arms. e) in the bulge, near the Orion arm.

16. Copyright © 2010 Pearson Education, Inc. a) measuring distances with Cepheid variable stars. b) identifying the mass of the Galaxy’s central black hole. c) determining the masses of stars in an eclipsing binary system. d) using spectroscopic parallax to measure distances to stars. Question 14-3 The period – luminosity relationship is a crucial component of

17. Copyright © 2010 Pearson Education, Inc. a) measuring distances with Cepheid variable stars. b) identifying the mass of the Galaxy’s central black hole. c) determining the masses of stars in an eclipsing binary system. d) using spectroscopic parallax to measure distances to stars. Question 14-3 The period – luminosity relationship is a crucial component of Cepheid variable stars with longer periods have higher actual luminosities; short-period Cepheids are dimmer.

18. Copyright © 2010 Pearson Education, Inc. a) tidal forces from the Andromeda Galaxy. b) accretion disks around neutron stars. c) gamma-ray bursts. d) gravitation from globular clusters. e) a supermassive black hole. Question 14 - 4 High-speed motion of gas and stars near the Milky Way Galaxy’s center is explained by

19. Copyright © 2010 Pearson Education, Inc. Question 14 - 4 High-speed motion of gas and stars near the Milky Way Galaxy’s center is explained by Recent observations estimate the black hole to be 4 million solar masses. a) tidal forces from the Andromeda Galaxy. b) accretion disks around neutron stars. c) gamma-ray bursts. d) gravitation from globular clusters. e) a supermassive black hole.

20. Copyright © 2010 Pearson Education, Inc. a) a spiral galaxy. b) a barred spiral galaxy. c) an elliptical galaxy. d) a quasar. e) an irregular galaxy. Question 14 - 5 Detailed measurements of the disk suggest that our Milky Way is

21. Copyright © 2010 Pearson Education, Inc. a) a spiral galaxy. b) a barred spiral galaxy. c) an elliptical galaxy. d) a quasar. e) an irregular galaxy. Question 14 - 5 Detailed measurements of the disk suggest that our Milky Way is Measurements of stellar motion in and near the bulge imply that it is football shaped, about half as wide as it is long, characteristic of a barred spiral galaxy.

22. Copyright © 2010 Pearson Education, Inc. a) the Sun’s mass and velocity in orbit around the galactic center b) the rotation of the bulge and disk components c) the Sun’s age and age of globular cluster stars d) the motion of spiral arms and the mass of the central black hole e) the Sun’s orbital period and distance from the center Question 14 - 6 What two observations allow us to estimate the Galaxy’s mass?

23. Copyright © 2010 Pearson Education, Inc. Question 14 - 6 What two observations allow us to estimate the Galaxy’s mass? Use the modified form of Kepler’s law to find the mass: Total mass = (orbital size) 3 / (orbital period) 2 a) the Sun’s mass and velocity in orbit around the galactic center b) the rotation of the bulge and disk components c) the Sun’s age and age of the globular cluster stars d) the motion of spiral arms and mass of the central black hole e) the Sun’s orbital period and distance from the center

24. Copyright © 2010 Pearson Education, Inc. a) the spiral arms formed first. b) the globular clusters formed first. c) the disk component started out thin and grew. d) spiral density waves formed first. e) the bar in the bulge formed first. Question 14 - 7 In the formation of our Galaxy

25. Copyright © 2010 Pearson Education, Inc. a) the spiral arms formed first. b) the globular clusters formed first. c) the disk component started out thin and grew. d) spiral density waves formed first. e) the bar in the bulge formed first. Question 14 - 7 In the formation of our Galaxy Globular clusters contain very old stars, no gas or dust, and orbit around the center randomly.

26. Copyright © 2010 Pearson Education, Inc. a) the waves penetrate dusty cocoons to reveal star formation. b) it reflects from the Galaxy’s core. c) the waves are not absorbed by galactic black holes. d) it can be used to map out the cool hydrogen in spiral arms. e) radio waves provide a distance measurement like parallax. Question 14 - 8 21-cm radio radiation is useful in studying our Galaxy because

27. Copyright © 2010 Pearson Education, Inc. a) the waves penetrate dusty cocoons to reveal star formation. b) it reflects from the Galaxy’s core. c) the waves are not absorbed by galactic black holes. d) it can be used to map out the cool hydrogen in spiral arms. e) radio waves provide a distance measurement like parallax. Question 14 - 8 21-cm radio radiation is useful in studying our Galaxy because The Doppler shifts of 21-cm radiation from hydrogen in the spiral arms provides astronomers with a tool to map out the Galaxy’s structure.

28. Copyright © 2010 Pearson Education, Inc. a) OB associations b) open clusters c) giant molecular clouds d) emission nebulae e) Population II red giant stars Question 14 - 9 Which of these is not a typical part of our Galaxy’s spiral arms?

29. Copyright © 2010 Pearson Education, Inc. a) OB associations b) open clusters c) giant molecular clouds d) emission nebulae e) Population II red giant stars Question 14 - 9 Which of these is not a typical part of our Galaxy’s spiral arms? The spiral arms contain gas, dust, molecular clouds, new clusters, and Population I stars.

30. Copyright © 2010 Pearson Education, Inc. Question 14 - 10 a) 21-cm maps of the spiral arms b) the rotation curve of the outer edges of the Galaxy c) orbits of open clusters in the disk d) infrared observations of new star- forming regions e) X-ray images of other galaxies What suggests that the mass of our Galaxy extends farther than its visible disk?

31. Copyright © 2010 Pearson Education, Inc. a) 21-cm maps of the spiral arms b) the rotation curve of the outer edges of the Galaxy c) orbits of open clusters in the disk d) infrared observations of new star- forming regions e) X-ray images of other galaxies Question 14 - 10 What suggests that the mass of our Galaxy extends farther than its visible disk? The outer edges of the Galaxy’s disk rotate much faster than they should. Most of the mass of the Galaxy must be dark matter.

32. Copyright © 2010 Pearson Education, Inc. a) disk and spiral arms. b) halo. c) central bulge. d) open clusters. e) companion galaxies, the Magellanic Clouds. Question 15 - 1 Based on their shapes and stars, elliptical galaxies are most like the Milky Way’s

33. Copyright © 2010 Pearson Education, Inc. a) disk and spiral arms. b) halo. c) central bulge. d) open clusters. e) companion galaxies, the Magellanic Clouds. Question 15 - 1 Based on their shapes and stars, elliptical galaxies are most like the Milky Way’s Like the stars and globular clusters in our halo, elliptical galaxies contain little or no gas and dust to make new stars.

34. Copyright © 2010 Pearson Education, Inc. a) ongoing star formation b) a disk, bulge, and halo c) globular clusters in the halo d) open clusters in the disk e) all of the above Question 15 - 2 What property is shared by spiral galaxies?

35. Copyright © 2010 Pearson Education, Inc. a) ongoing star formation b) a disk, bulge, and halo c) globular clusters in the halo d) open clusters in the disk e) all of the above Question 15 - 2 What property is shared by spiral galaxies? M-51, a Type Sb spiral

36. Copyright © 2010 Pearson Education, Inc. a) giant globular clusters in the halo. b) small irregular galaxies that orbit the Milky Way. c) large molecular clouds in the disk of our Galaxy. d) the brightest ionized hydrogen regions in our Galaxy. e) spiral nebulae originally discovered by Herschel. Question 15 - 3 The Magellanic Clouds are

37. Copyright © 2010 Pearson Education, Inc. a) giant globular clusters in the halo. b) small irregular galaxies that orbit the Milky Way. c) large molecular clouds in the disk of our Galaxy. d) the brightest ionized hydrogen regions in our Galaxy. e) spiral nebulae originally discovered by Herschel. Question 15 - 3 The Magellanic Clouds are

38. Copyright © 2010 Pearson Education, Inc. Question 15 - 4 Hubble took spectra of galaxies in the 1930s. What did he find? a) Most galaxies showed redshifts. b) All galaxies showed blueshifts. c) Galaxies showed about half redshifts and half blueshifts. d) Galaxies showed no line shifts at all. e) Some galaxies showed a redshift that changed into a blueshift at other times.

39. Copyright © 2010 Pearson Education, Inc. Question 15 - 4 Hubble took spectra of galaxies in the 1930s. What did he find? Redshifts of galaxies indicate they are moving away from us. a) Most galaxies showed redshifts. b) All galaxies showed blueshifts. c) Galaxies showed about half redshifts and half blueshifts. d) Galaxies showed no line shifts at all. e) Some galaxies showed a redshift that changed into a blueshift at other times.

40. Copyright © 2010 Pearson Education, Inc. a) more distant galaxies showing greater blueshifts. b) distant quasars appearing proportionally dimmer. c) more distant galaxies showing greater redshifts. d) slowly varying Cepheid variables appearing brighter. e) more distant galaxies appearing younger. Question 15 - 5 Hubble’s law is based on

41. Copyright © 2010 Pearson Education, Inc. a) more distant galaxies showing greater blueshifts. b) distant quasars appearing proportionally dimmer. c) more distant galaxies showing greater redshifts. d) slowly varying Cepheid variables appearing brighter. e) more distant galaxies appearing younger. Question 15 - 5 Hubble’s law is based on

42. Copyright © 2010 Pearson Education, Inc. Question 15 - 6 Hubble’s constant measures a) the density of galaxies in the universe. b) the luminosity of distant galaxies. c) the reddening of light from dust clouds. d) the speed of a galaxy. e) the rate of expansion of the universe.

43. Copyright © 2010 Pearson Education, Inc. a) the density of galaxies in the universe. b) the luminosity of distant galaxies. c) the reddening of light from dust clouds. d) the speed of a galaxy. e) the rate of expansion of the universe. Question 15 - 6 Hubble’s constant measures Hubble’s law relates how fast galaxies are moving away from us at different distances. A larger value for H 0 implies a faster expansion rate. Velocity = H 0 x Distance

44. Copyright © 2010 Pearson Education, Inc. a) the size of the universe. b) distances to galaxies. c) the speed of recession of galaxies. d) the density of matter in the universe. e) the temperature of the Big Bang. Question 15 - 7 To calibrate Hubble’s constant, astronomers must determine

45. Copyright © 2010 Pearson Education, Inc. a) the size of the universe. b) distances to galaxies. c) the speed of recession of galaxies. d) the density of matter in the universe. e) the temperature of the Big Bang. Question 15 - 7 To calibrate Hubble’s constant, astronomers must determine Distances to galaxies are determined using a variety of “standard candles,” including Cepheid variables, supernova explosions, model galaxies, and model clusters.

46. Copyright © 2010 Pearson Education, Inc. a) the universe is static. b) the universe is collapsing. c) the universe is expanding. d) the Milky Way is the center of the universe. e) There is no accepted interpretation. Question 15 - 8 Hubble’s discovery of galaxy redshifts means

47. Copyright © 2010 Pearson Education, Inc. a) the universe is static. b) the universe is collapsing. c) the universe is expanding. d) the Milky Way is the center of the universe. e) There is no accepted interpretation. Question 15 - 8 Hubble’s discovery of galaxy redshifts means

48. Copyright © 2010 Pearson Education, Inc. a) they generate energy partly through H to He fusion like stars. b) they show spectra similar to extremely bright O stars. c) their luminosity varies like eclipsing binary stars. d) in short exposure photographs, their images appear stellar. e) they are dense concentrations of millions of stars. Question 15 - 9 Quasars are “quasi-stellar” because

49. Copyright © 2010 Pearson Education, Inc. a) they generate energy partly through H to He fusion like stars. b) they show spectra similar to extremely bright O stars. c) their luminosity varies like eclipsing binary stars. d) in short exposure photographs, their images appear stellar. e) they are dense concentrations of millions of stars. Question 15 - 9 Quasars are “quasi-stellar” because Although short-exposure images can appear starlike, many quasars show jets or other signs of intense activity.

50. Copyright © 2010 Pearson Education, Inc. a) supermassive black holes at their cores. b) dark matter. c) self-sustaining star formation. d) spiral density waves. e) hypernova explosions. Question 15 - 10 Seyfert and radio galaxies could be powered by

51. Copyright © 2010 Pearson Education, Inc. a) supermassive black holes at their cores. b) dark matter. c) self-sustaining star formation. d) spiral density waves. e) hypernova explosions. Question 15 - 10 Seyfert and radio galaxies could be powered by The Circinus Galaxy, a Seyfert galaxy about 4 Mpc away

52. Copyright © 2010 Pearson Education, Inc. a) sudden bursts of star formation. b) supernova chain reactions in the core. c) the collapse of the core into a larger black hole. d) close encounters with a nearby galaxy. e) dark matter becoming visible and emitting light. Question 15 - 11 In active galaxies, the central engine can be “fed” by

53. Copyright © 2010 Pearson Education, Inc. a) sudden bursts of star formation. b) supernova chain reactions in the core. c) the collapse of the core into a larger black hole. d) close encounters with a nearby galaxy. e) dark matter becoming visible and emitting light. Question 15 - 11 In active galaxies, the central engine can be “fed” by Collisions or tidal interaction between galaxies can provide new fuel to power the supermassive black hole engines of active galaxies.

54. Copyright © 2010 Pearson Education, Inc. a) makes up about 90 percent of the matter in the universe. b) is best detected by the largest optical telescopes. c) makes up about 10 percent of the matter in clusters of galaxies. d) exists but has no observable effects on galaxies. e) is the result of gas and dust. Question 16 - 1 Based on galactic rotation curves and motions in clusters of galaxies, dark matter

55. Copyright © 2010 Pearson Education, Inc. a) makes up about 90 percent of the matter in the universe. b) is best detected by the largest optical telescopes. c) makes up about 10 percent of the matter in clusters of galaxies. d) exists but has no observable effects on galaxies. e) is the result of gas and dust. Question 16 - 1 Based on galactic rotation curves and motions in clusters of galaxies, dark matter

56. Copyright © 2010 Pearson Education, Inc. a) are much rarer than collisions between stars. b) can transform elliptical galaxies into spirals. c) trigger Type II supernova explosions in the halo. d) cause gas and dust clouds to collide, leading to rapid star formation. Question 16 - 2 Collisions between galaxies

57. Copyright © 2010 Pearson Education, Inc. a) are much rarer than collisions between stars. b) can transform elliptical galaxies into spirals. c) trigger Type II supernova explosions in the halo. d) cause gas and dust clouds to collide, leading to rapid star formation. Question 16 - 2 Collisions between galaxies Galaxies are relatively close compared with their size. In clusters of galaxies, collisions clearly occur.

58. Copyright © 2010 Pearson Education, Inc. a) globular cluster stars. b) giant molecular clouds. c) central bulge stars. d) open clusters. e) disk stars. Question 16 - 3 When spiral galaxies collide, the greatest impact occurs on their

59. Copyright © 2010 Pearson Education, Inc. a) globular cluster stars. b) giant molecular clouds. c) central bulge stars. d) open clusters. e) disk stars. Question 16 - 3 When spiral galaxies collide, the greatest impact occurs on their

60. Copyright © 2010 Pearson Education, Inc. Question 16 - 4 a) giant ellipticals b) irregulars c) spirals d) active galaxies e) radio galaxies Due to the density and collisions among galaxies, ___________ are rare in the centers of clusters.

61. Copyright © 2010 Pearson Education, Inc. a) giant ellipticals b) irregulars c) spirals d) active galaxies e) radio galaxies Question 16 - 4 Due to the density and collisions among galaxies, ___________ are rare in the centers of clusters. The gas, dust, and disks of spiral galaxies are tidally disrupted, and even destroyed, in the centers of dense clusters, which are often dominated by giant elliptical galaxies.

62. Copyright © 2010 Pearson Education, Inc. a) the source of energy is very small. b) energy is coming from matter and antimatter. c) the energy source is rotating rapidly. d) a chain reaction of supernovas occurs. e) there are many separate sources of energy in the core. Question 16 - 5 The rapid variation of brightness of quasars indicates

63. Copyright © 2010 Pearson Education, Inc. a) the source of energy is very small. b) energy is coming from matter and antimatter. c) the energy source is rotating rapidly. d) a chain reaction of supernovas occurs. e) there are many separate sources of energy in the core. Question 16 - 5 The rapid variation of brightness of quasars indicates The size of an object cannot be larger than the distance light can travel in the time it takes to change its brightness.

64. Copyright © 2010 Pearson Education, Inc. a) as it was when the universe was 1 billion years old. b) as it will be 1 billion years from now. c) as it was 1 billion years ago. d) as it is today, but redshifted 10 percent of the speed of light. e) as it was just after the Big Bang. Question 16 - 6 A galaxy seen 1 billion light-years away means we see it

65. Copyright © 2010 Pearson Education, Inc. a) as it was when the universe was 1 billion years old. b) as it will be 1 billion years from now. c) as it was 1 billion years ago. d) as it is today, but redshifted 10 percent of the speed of light. e) as it was just after the Big Bang. Question 16 - 6 A galaxy seen 1 billion light-years away means we see it Looking farther away in space means looking back further in time, to when the object (and universe) was younger.

66. Copyright © 2010 Pearson Education, Inc. a) a smooth, continuous, and homogeneous arrangement of clusters. b) large voids, with most of the galaxies lying in filaments and sheets. c) a large supercluster at the center of the universe. d) a central void with walls of galaxies at the edge of the universe. Question 16 - 7 The large-scale distribution of galaxies in the universe reveals

67. Copyright © 2010 Pearson Education, Inc. a) a smooth, continuous, and homogeneous arrangement of clusters. b) large voids, with most of the galaxies lying in filaments and sheets. c) a large supercluster at the center of the universe. d) a central void with walls of galaxies at the edge of the universe. Question 16 - 7 The large-scale distribution of galaxies in the universe reveals

68. Copyright © 2010 Pearson Education, Inc. a) total mass of stars, gas, and dark matter. b) central supermassive black hole. c) globular clusters. d) magnetic fields. e) intergalactic gas. Question 16 - 8 The lensing of a distant quasar is produced in a foreground galaxy by its

69. Copyright © 2010 Pearson Education, Inc. a) total mass of stars, gas, and dark matter. b) central supermassive black hole. c) globular clusters. d) magnetic fields. e) intergalactic gas. Question 16 - 8 The lensing of a distant quasar is produced in a foreground galaxy by its The twin quasar AC114 has two images of the same object.

70. Copyright © 2010 Pearson Education, Inc. a) the Milky Way must be located at the edge of the universe. b) the Milky Way is at the center of the universe. c) the universe is expanding. d) the sky is dark at night. e) the universe has not changed significantly. Question 17 - 1 Because distant galaxies in every direction are moving away from us,

71. Copyright © 2010 Pearson Education, Inc. a) the Milky Way must be located at the edge of the universe. b) the Milky Way is at the center of the universe. c) the universe is expanding. d) the sky is dark at night. e) the universe has not changed significantly. Question 17 - 1 Because distant galaxies in every direction are moving away from us,

72. Copyright © 2010 Pearson Education, Inc. a) the size of the universe. b) the age of the universe. c) the shape of the universe. d) the temperature of the universe. e) the distance the universe has expanded. Question 17 - 2 Hubble’s constant, H 0, can be related to

73. Copyright © 2010 Pearson Education, Inc. a) the size of the universe. b) the age of the universe. c) the shape of the universe. d) the temperature of the universe. e) the distance the universe has expanded. Question 17 - 2 Hubble’s constant, H 0, can be related to H 0 is currently estimated to be about 70 km/sec/Mpc. This translates to an age for the universe of about 14 billion years.

74. Copyright © 2010 Pearson Education, Inc. a) a Doppler shift of the random motions of galaxies. b) an aging of light as the universe ages. c) space itself expanding with time, stretching light. d) the result of the Milky Way’s position at the center. e) due to the temperature differences in the early and late universe. Question 17 - 3 The redshift of galaxies is explained best as

75. Copyright © 2010 Pearson Education, Inc. a) a Doppler shift of the random motions of galaxies. b) an aging of light as the universe ages. c) space itself expanding with time, stretching light. d) the result of the Milky Way’s position at the center. e) due to the temperature differences in the early and late universe. Question 17 - 3 The redshift of galaxies is explained best as As the universe expands, photons of radiation are stretched in wavelength as they move through space.

76. Copyright © 2010 Pearson Education, Inc. a) is infinitely old and getting larger. b) began expanding long ago, and has a finite age. c) will slow down because of dark matter. d) has repeatedly expanded and contracted. e) will eventually stop and recollapse. Question 17 - 4 Hubble’s law implies that the universe

77. Copyright © 2010 Pearson Education, Inc. a) is infinitely old and getting larger. b) began expanding long ago, and has a finite age. c) will slow down because of dark matter. d) has repeatedly expanded and contracted. e) will eventually stop and recollapse. Question 17 - 4 Hubble’s law implies that the universe Using the Hubble constant H 0, astronomers can estimate that the universe was born about 14 billion years ago.

78. Copyright © 2010 Pearson Education, Inc. Question 17 - 5 The cosmic microwave background radiation is a) evidence supporting the Big Bang. b) proof that the universe is getting warmer. c) a result of the hot intergalactic gas between clusters. d) the observable form of dark energy. e) released from the first generation of stars in the universe.

79. Copyright © 2010 Pearson Education, Inc. a) evidence supporting the Big Bang. b) proof that the universe is getting warmer. c) a result of the hot intergalactic gas between clusters. d) the observable form of dark energy. e) released from the first generation of stars in the universe. Question 17 - 5 The cosmic microwave background radiation is The radiation observed is the “fossil remnant” of the primeval fireball that existed at the very beginning of the universe.

80. Copyright © 2010 Pearson Education, Inc. a) is explained by general relativity. b) results from the presence of dark matter. c) is a statement of Olbers’ paradox. d) is the cosmological principle. e) occurs if the universe is static and unchanging. Question 17 - 6 The darkness of the sky in an infinite universe

81. Copyright © 2010 Pearson Education, Inc. a) is explained by general relativity. b) results from the presence of dark matter. c) is a statement of Olbers’ paradox. d) is the cosmological principle. e) occurs if the universe is static and unchanging. Question 17 - 6 The darkness of the sky in an infinite universe If the universe is homogeneous in composition, and appears the same in all directions, then for the sky to be dark, it must be either finite in age, or evolving in time, or both.

82. Copyright © 2010 Pearson Education, Inc. a) the universe will eventually stop expanding and recollapse. b) dark matter will dominate over dark energy. c) the universe will stop expanding and remain stationary. d) dark energy will dominate over dark matter. e) the universe will not stop expanding. Question 17 - 7 In a closed universe

83. Copyright © 2010 Pearson Education, Inc. a) the universe will eventually stop expanding and recollapse. b) dark matter will dominate over dark energy. c) the universe will stop expanding and remain stationary. d) dark energy will dominate over dark matter. e) the universe will not stop expanding. Question 17 - 7 In a closed universe Greater density means more matter in a smaller volume, and gravity will be strong enough to stop the expansion and cause a “Big Crunch.”

84. Copyright © 2010 Pearson Education, Inc. a) there is more matter than energy. b) the universe is closed, and will recollapse. c) the universe is open, and will keep expanding. d) dark matter will dominate, and galaxies will stop expanding. e) there was more helium than hydrogen created in the Big Bang. Question 17 - 8 If the density of the universe is greater than “critical”,

85. Copyright © 2010 Pearson Education, Inc. a) there is more matter than energy. b) the universe is closed, and will recollapse. c) the universe is open, and will keep expanding. d) dark matter will dominate, and galaxies will stop expanding. e) there was more helium than hydrogen created in the Big Bang. Question 17 - 8 If the density of the universe is greater than “critical”,

86. Copyright © 2010 Pearson Education, Inc. Question 17 - 9 In the first few minutes after the Big Bang a) the universe cooled and formed neutral matter. b) the cosmic microwave background radiation was released. c) electrons recombined with protons. d) hydrogen fused into deuterium and then helium. e) the universe was governed by one unified super-force.

87. Copyright © 2010 Pearson Education, Inc. a) the universe cooled and formed neutral matter. b) the cosmic microwave background radiation was released. c) electrons recombined with protons. d) hydrogen fused into deuterium and then helium. e) the universe was governed by one unified super-force. Question 17 - 9 In the first few minutes after the Big Bang The production of elements heavier than hydrogen by nuclear fusion is “primordial nucleosynthesis.” The amount of deuterium we see today is an important clue to the density of this early universe.

88. Copyright © 2010 Pearson Education, Inc. a) the Steady State Theory. b) the Grand Unified Theories. c) the Inflationary epoch. d) dark matter. e) decoupling of matter from radiation. Question 17 - 10 The universe appears flat; this is explained by

89. Copyright © 2010 Pearson Education, Inc. a) the Steady State Theory. b) the Grand Unified Theories. c) the Inflationary epoch. d) dark matter. e) decoupling of matter from radiation. Question 17 - 10 The universe appears flat; this is explained by