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Chapter 23 Reading Quiz Clickers
The Cosmic Perspective Seventh Edition
© 2014 Pearson Education, Inc.
Dark Matter, Dark Energy, and the Fate of the Universe
Chapter 23
© 2014 Pearson Education, Inc.
23.1 Unseen Influences in the Cosmos
• What do we mean by dark matter and dark energy?
Chapter 23
© 2014 Pearson Education, Inc.
Which of the following is not true about dark matter?
a) Evidence for dark matter has been building for many decades.
b) Dark matter and dark energy are two aspects of the same phenomenon.
c) Dark matter is inferred based on unseen gravitational effects in galaxies.
d) Dark matter is the dominant source of gravity in the universe.
Chapter 23
© 2014 Pearson Education, Inc.
Which of the following is not true about dark matter?
a) Evidence for dark matter has been building for many decades.
b) Dark matter and dark energy are two aspects of the same phenomenon.
c) Dark matter is inferred based on unseen gravitational effects in galaxies.
d) Dark matter is the dominant source of gravity in the universe.
Chapter 23
© 2014 Pearson Education, Inc.
23.2 Evidence for Dark Matter
• What is the evidence for dark matter in galaxies? • What is the evidence for dark matter in clusters of
galaxies? • Does dark matter really exist? • What might dark matter be made of?
Chapter 23
© 2014 Pearson Education, Inc.
What is a rotation curve of a galaxy?
a) It is the shape of a spiral galaxy's spiral arms. b) It is a plot of the change of a galaxy's rotation rate
with time. c) It is a plot of the rotation rate in a galaxy as a
function of distance from the galaxy's center. d) It is the path a galaxy follows around the center of a
cluster of galaxies.
Chapter 23
© 2014 Pearson Education, Inc.
What is a rotation curve of a galaxy?
a) It is the shape of a spiral galaxy's spiral arms. b) It is a plot of the change of a galaxy's rotation rate
with time. c) It is a plot of the rotation rate in a galaxy as a
function of distance from the galaxy's center. d) It is the path a galaxy follows around the center of a
cluster of galaxies.
Chapter 23
© 2014 Pearson Education, Inc.
How do galactic rotation curves suggest the presence of dark matter?
a) They go to higher speeds at the centers of galaxies.
b) They stay at higher speeds in the outskirts of galaxies.
c) They go to lower speeds at the centers of galaxies. d) They stay at lower speeds at the outskirts of
galaxies.
Chapter 23
© 2014 Pearson Education, Inc.
How do galactic rotation curves suggest the presence of dark matter?
a) They go to higher speeds at the centers of galaxies.
b) They stay at higher speeds in the outskirts of galaxies.
c) They go to lower speeds at the centers of galaxies. d) They stay at lower speeds at the outskirts of
galaxies.
Chapter 23
© 2014 Pearson Education, Inc.
Where is most of the Milky Way's dark matter located?
a) in the central bulge b) in the disk c) in the halo d) in the plane of the disk, beyond the outermost stars
Chapter 23
© 2014 Pearson Education, Inc.
Where is most of the Milky Way's dark matter located?
a) in the central bulge b) in the disk c) in the halo d) in the plane of the disk, beyond the outermost stars
Chapter 23
© 2014 Pearson Education, Inc.
What fraction of the mass of spiral galaxies is in dark matter?
a) about 1% b) about 10% c) about 30% d) about 60% e) about 90%
Chapter 23
© 2014 Pearson Education, Inc.
What fraction of the mass of spiral galaxies is in dark matter?
a) about 1% b) about 10% c) about 30% d) about 60% e) about 90%
Chapter 23
© 2014 Pearson Education, Inc.
How does the amount of dark matter in clusters of galaxies compare to the amount of visible matter?
a) There are about equal amounts of dark matter and visible matter.
b) There is about twice as much dark matter as visible matter. c) There is about 10 times as much dark matter as visible
matter. d) There is about 50 times as much dark matter as visible
matter. e) There is about 1000 times as much dark matter as visible
matter.
Chapter 23
© 2014 Pearson Education, Inc.
How does the amount of dark matter in clusters of galaxies compare to the amount of visible matter?
a) There are about equal amounts of dark matter and visible matter.
b) There is about twice as much dark matter as visible matter. c) There is about 10 times as much dark matter as visible
matter. d) There is about 50 times as much dark matter as visible
matter. e) There is about 1000 times as much dark matter as visible
matter.
Chapter 23
© 2014 Pearson Education, Inc.
How much more mass is in the hot gas of the intracluster medium than in stars in clusters of galaxies?
a) There are about equal amounts of hot gas and stars in galaxy clusters.
b) about 7 times as much hot gas c) about 50 times as much hot gas d) about 300 times as much hot gas
Chapter 23
© 2014 Pearson Education, Inc.
How much more mass is in the hot gas of the intracluster medium than in stars in clusters of galaxies?
a) There are about equal amounts of hot gas and stars in galaxy clusters.
b) about 7 times as much hot gas c) about 50 times as much hot gas d) about 300 times as much hot gas
Chapter 23
© 2014 Pearson Education, Inc.
Which of the following is not a technique used to measure the total mass of a cluster of galaxies?
a) observations of gravitational lensing of galaxies behind the cluster
b) observations of the temperature of the hot intracluster medium
c) observations of the luminosity of the galaxies d) observations of the motions of galaxies within the
cluster
Chapter 23
© 2014 Pearson Education, Inc.
Which of the following is not a technique used to measure the total mass of a cluster of galaxies?
a) observations of gravitational lensing of galaxies behind the cluster
b) observations of the temperature of the hot intracluster medium
c) observations of the luminosity of the galaxies d) observations of the motions of galaxies within the
cluster
Chapter 23
© 2014 Pearson Education, Inc.
Which of the following must be true if dark matter does not exist?
a) The theory of general relativity is incorrect or incomplete.
b) The theory of special relativity is incorrect or incomplete.
c) The cosmological principle is incorrect. d) any of the above e) none of the above
Chapter 23
© 2014 Pearson Education, Inc.
Which of the following must be true if dark matter does not exist?
a) The theory of general relativity is incorrect or incomplete.
b) The theory of special relativity is incorrect or incomplete.
c) The cosmological principle is incorrect. d) any of the above e) none of the above
Chapter 23
© 2014 Pearson Education, Inc.
Which of the following is not true of WIMPs
a) They are baryons. b) They have no charge. c) They are also called cold dark matter. d) They are believed to make up the majority of dark
matter in the universe. e) They are subatomic particles.
Chapter 23
© 2014 Pearson Education, Inc.
Which of the following is not true of WIMPs
a) They are baryons. b) They have no charge. c) They are also called cold dark matter. d) They are believed to make up the majority of dark
matter in the universe. e) They are subatomic particles.
Chapter 23
© 2014 Pearson Education, Inc.
23.3 Dark Matter and Galaxy Formation
• What is the role of dark matter in galaxy formation? • What are the largest structures in the universe?
Chapter 23
© 2014 Pearson Education, Inc.
How did dark matter contribute to the formation of galaxies?
a) The gravitational pull of dark matter triggered the collapse of the first star-forming regions.
b) The gravitational pull of dark matter led to the formation of protogalactic clouds.
c) The gravitational pull of dark matter prevented young galaxies from blowing apart from superbubbles created by the first generation of supernovae.
d) Dark matter helped radiate energy allowing protogalactic clouds to collapse.
Chapter 23
© 2014 Pearson Education, Inc.
How did dark matter contribute to the formation of galaxies?
a) The gravitational pull of dark matter triggered the collapse of the first star-forming regions.
b) The gravitational pull of dark matter led to the formation of protogalactic clouds.
c) The gravitational pull of dark matter prevented young galaxies from blowing apart from superbubbles created by the first generation of supernovae.
d) Dark matter helped radiate energy allowing protogalactic clouds to collapse.
Chapter 23
© 2014 Pearson Education, Inc.
What is the Sloan Great Wall?
a) the dense distribution of primitive galaxies at the boundary of the observable universe
b) a vast cloud of intergalactic gas that blocks our view of certain distant regions of the universe
c) a huge spherical bubble formed by galaxies, surrounding a void
d) a huge sheet of galaxies more than 1 billion light-years long
Chapter 23
© 2014 Pearson Education, Inc.
What is the Sloan Great Wall?
a) the dense distribution of primitive galaxies at the boundary of the observable universe
b) a vast cloud of intergalactic gas that blocks our view of certain distant regions of the universe
c) a huge spherical bubble formed by galaxies, surrounding a void
d) a huge sheet of galaxies more than 1 billion light-years long
Chapter 23
© 2014 Pearson Education, Inc.
23.4 Dark Energy and the Fate of the Universe
• Why is accelerating expansion evidence for dark energy?
• Why is flat geometry evidence for dark energy? • What is the fate of the universe?
Chapter 23
© 2014 Pearson Education, Inc.
Including dark matter, what is the apparent density of the universe compared to the critical density?
a) one one-thousandth (0.1%) of the critical density b) one two-hundredth (0.5%) of the critical density c) one-tenth of the critical density d) one-fourth of the critical density e) approximately equal to the critical density
Chapter 23
© 2014 Pearson Education, Inc.
Including dark matter, what is the apparent density of the universe compared to the critical density?
a) one one-thousandth (0.1%) of the critical density b) one two-hundredth (0.5%) of the critical density c) one-tenth of the critical density d) one-fourth of the critical density e) approximately equal to the critical density
Chapter 23
© 2014 Pearson Education, Inc.
If the density of the universe is less than the critical density and there is dark energy, what is the expansion pattern of the universe?
a) an accelerating universe b) a coasting universe c) a critical universe d) a recollapsing universe e) a repeating universe
Chapter 23
© 2014 Pearson Education, Inc.
If the density of the universe is less than the critical density and there is dark energy, what is the expansion pattern of the universe?
a) an accelerating universe b) a coasting universe c) a critical universe d) a recollapsing universe e) a repeating universe
Chapter 23
© 2014 Pearson Education, Inc.
What observations provide evidence for dark energy?
a) distances and red shifts of white dwarf supernovae
b) distances and red shifts of quasars c) spatial distribution and red shifts of quasars d) velocity dispersion of galaxy clusters
Chapter 23
© 2014 Pearson Education, Inc.
What observations provide evidence for dark energy?
a) distances and red shifts of white dwarf supernovae
b) distances and red shifts of quasars c) spatial distribution and red shifts of quasars d) velocity dispersion of galaxy clusters
Chapter 23
© 2014 Pearson Education, Inc.
How long will it take for the most massive black holes to evaporate?
a) 10100 years b) 1040 years c) 1017 years d) 1010 years
Chapter 23
© 2014 Pearson Education, Inc.
How long will it take for the most massive black holes to evaporate?
a) 10100 years b) 1040 years c) 1017 years d) 1010 years
