Astronomy A BEGINNER’S GUIDE TO THE UNIVERSE EIGHTH EDITION CHAPTER 17 Cosmology Clickers © 2017 Pearson Education, Inc Question Because distant galaxies in every direction are moving away from us, the a) b) c) d) e) © 2017 Pearson Education, Inc 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 Question Because distant galaxies in every direction are moving away from us, the a) b) c) d) e) © 2017 Pearson Education, Inc 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 Question Hubble’s constant, H0, can be related to the a) b) c) d) e) © 2017 Pearson Education, Inc size of the universe age of the universe shape of the universe temperature of the universe distance the universe has expanded Question Hubble’s constant, H0, can be related to the a) b) c) d) e) 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 The redshift of galaxies is explained best as a) b) c) d) e) © 2017 Pearson Education, Inc 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 Question The redshift of galaxies is explained best as a) b) c) d) e) 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 Hubble’s law implies that the universe a) b) c) d) e) © 2017 Pearson Education, Inc 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 Question Hubble’s law implies that the universe a) b) c) d) e) 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 The cosmic microwave background radiation is a) b) c) d) e) © 2017 Pearson Education, Inc 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 Question The cosmic microwave background radiation is a) b) c) d) e) 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 The darkness of the sky in an infinite universe a) b) c) d) e) © 2017 Pearson Education, Inc 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 Question The darkness of the sky in an infinite universe a) b) c) d) e) 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 In a closed universe, a) the universe will eventually stop expanding and recollapse b) c) d) e) © 2017 Pearson Education, Inc 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 Question In a closed universe, a) the universe will eventually stop expanding and recollapse b) c) d) e) 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 If the density of the universe is greater than “critical,” then a) b) c) d) 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 e) © 2017 Pearson Education, Inc there was more helium than hydrogen created in the Big Bang Question If the density of the universe is greater than “critical,” then a) b) c) d) 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 e) there was more helium than hydrogen created in the Big Bang © 2017 Pearson Education, Inc Question In the first few minutes after the Big Bang, a) b) c) d) e) © 2017 Pearson Education, Inc 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 Question In the first few minutes after the Big Bang, a) b) c) d) e) 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 a) b) c) d) e) © 2017 Pearson Education, Inc the steady state theory the Grand Unified Theories the inflationary epoch dark matter decoupling of matter from radiation Question 10 The universe appears flat; this is explained by a) b) c) d) e) 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 a) b) microwaves combining with visible photons protons combining with electrons to form neutral hydrogen in the decoupling epoch c) d) e) © 2017 Pearson Education, Inc 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 Question 11 Cosmic microwave background radiation is created in the early universe by a) microwaves combining with visible photons b) protons combining with electrons to form neutral hydrogen in the decoupling epoch c) four hydrogen nuclei fusing to form helium d) e) © 2017 Pearson Education, Inc starlight from the first generation of stars redshifted to the microwave region of the spectrum electrons combining with anti-electrons ... 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... 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:... 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