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Question 1 Because distant galaxies in every direction are moving away from us, the Milky Way must be located at the edge of the universe. Milky Way is at the center of the universe. universe is expanding. sky is dark at night. universe has not changed significantly. Answer: c © 2017 Pearson Education, Inc.

Question 1 Because distant galaxies in every direction are moving away from us, the Milky Way must be located at the edge of the universe. Milky Way is at the center of the universe. universe is expanding. sky is dark at night. universe has not changed significantly. © 2017 Pearson Education, Inc.

Question 2 Hubble’s constant, H0, can be related to the size of the universe. age of the universe. shape of the universe. temperature of the universe. distance the universe has expanded. Answer: b © 2017 Pearson Education, Inc.

Question 2 Hubble’s constant, H0, can be related to the size of the universe. age of the universe. shape of the universe. temperature of the universe. distance the universe has expanded. Explanation: H0 is currently estimated to be about 70 km/sec/Mpc. This translates to an age for the universe of about 14 billion years. © 2017 Pearson Education, Inc.

Question 3 The redshift of galaxies is explained best as a Doppler shift of the random motions of galaxies. an aging of light as the universe ages. space itself expanding with time, stretching light. the result of the Milky Way’s position at the center. being due to the temperature differences in the early and late universe. Answer: c © 2017 Pearson Education, Inc.

Question 3 The redshift of galaxies is explained best as a Doppler shift of the random motions of galaxies. an aging of light as the universe ages. space itself expanding with time, stretching light. the result of the Milky Way’s position at the center. being due to the temperature differences in the early and late universe. Explanation: As the universe expands, photons of radiation are stretched inwavelength as they move through space. © 2017 Pearson Education, Inc.

Question 4 Hubble’s law implies that the universe is infinitely old and getting larger. began expanding long ago and has a finite age. will slow down because of dark matter. has repeatedly expanded and contracted. will eventually stop and recollapse. Answer: b © 2017 Pearson Education, Inc.

Question 4 Hubble’s law implies that the universe is infinitely old and getting larger. began expanding long ago and has a finite age. will slow down because of dark matter. has repeatedly expanded and contracted. will eventually stop and recollapse. Explanation: Using the Hubble constant H0, astronomers can estimate that the universe was born about 14 billion years ago. © 2017 Pearson Education, Inc.

Question 5 The cosmic microwave background radiation is evidence supporting the Big Bang. proof that the universe is getting warmer. a result of the hot intergalactic gas between clusters. the observable form of dark energy. released from the first generation of stars in the universe. Answer: a © 2017 Pearson Education, Inc.

Question 5 The cosmic microwave background radiation is evidence supporting the Big Bang. proof that the universe is getting warmer. a result of the hot intergalactic gas between clusters. the observable form of dark energy. released from the first generation of stars in the universe. Explanation: The radiation observed is the “fossil remnant” of the primeval fireball that existed at the very beginning of the universe. © 2017 Pearson Education, Inc.

Question 6 The darkness of the sky in an infinite universe is explained by general relativity. results from the presence of dark matter. is a statement of Olbers’s paradox. is the cosmological principle. occurs if the universe is static and unchanging. Answer: c © 2017 Pearson Education, Inc.

Question 6 The darkness of the sky in an infinite universe is explained by general relativity. results from the presence of dark matter. is a statement of Olbers’s paradox. is the cosmological principle. occurs if the universe is static and unchanging. Explanation: 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. © 2017 Pearson Education, Inc.

Question 7 In a closed universe, the universe will eventually stop expanding and recollapse. dark matter will dominate over dark energy. the universe will stop expanding and remain stationary. dark energy will dominate over dark matter. the universe will not stop expanding. Answer: a © 2017 Pearson Education, Inc.

Question 7 In a closed universe, the universe will eventually stop expanding and recollapse. dark matter will dominate over dark energy. the universe will stop expanding and remain stationary. dark energy will dominate over dark matter. the universe will not stop expanding. Explanation: Greater density means more matter in a smaller volume, and gravity will be strong enough to stop the expansion and cause a “Big Crunch.” © 2017 Pearson Education, Inc.

Question 8 If the density of the universe is greater than “critical,” then there is more matter than energy. the universe is closed and will recollapse. the universe is open and will keep expanding. dark matter will dominate, and galaxies will stop expanding. there was more helium than hydrogen created in the Big Bang. Answer: b © 2017 Pearson Education, Inc.

Question 8 If the density of the universe is greater than “critical,” then there is more matter than energy. the universe is closed and will recollapse. the universe is open and will keep expanding. dark matter will dominate, and galaxies will stop expanding. there was more helium than hydrogen created in the Big Bang. © 2017 Pearson Education, Inc.

Question 9 In the first few minutes after the Big Bang, the universe cooled and formed neutral matter. the cosmic microwave background radiation was released. electrons recombined with protons. hydrogen fused into deuterium and then helium. the universe was governed by one unified superforce. Answer: d © 2017 Pearson Education, Inc.

Question 9 In the first few minutes after the Big Bang, the universe cooled and formed neutral matter. the cosmic microwave background radiation was released. electrons recombined with protons. hydrogen fused into deuterium and then helium. the universe was governed by one unified superforce. Explanation: 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. © 2017 Pearson Education, Inc.

Question 10 The universe appears flat; this is explained by the steady state theory. the Grand Unified Theories. the inflationary epoch. dark matter. decoupling of matter from radiation. Answer: c © 2017 Pearson Education, Inc.

Question 10 The universe appears flat; this is explained by the steady state theory. the Grand Unified Theories. the inflationary epoch. dark matter. decoupling of matter from radiation. © 2017 Pearson Education, Inc.

Question 11 Cosmic microwave background radiation is created in the early universe by microwaves combining with visible photons. protons combining with electrons to form neutral hydrogen in the decoupling epoch. four hydrogen nuclei fusing to form helium. starlight from the first generation of stars redshifted to the microwave region of the spectrum. electrons combining with anti-electrons. Answer: b © 2017 Pearson Education, Inc.

Question 11 Cosmic microwave background radiation is created in the early universe by microwaves combining with visible photons. protons combining with electrons to form neutral hydrogen in the decoupling epoch. four hydrogen nuclei fusing to form helium. starlight from the first generation of stars redshifted to the microwave region of the spectrum. electrons combining with anti-electrons. © 2017 Pearson Education, Inc.