Question 1

When a gamma-ray photon undergoes pair production, what is one possibility for the final products?

Accepted Answer

A)  an electron and a positron (the antielectron) 
B)  an electron and an antineutrino 
C)  a proton, an electron, and an antineutrino 
D)  two X-ray photons, each with half the energy of the original gamma ray 
A)  an electron and a positron (the antielectron) 
B)  an electron and an antineutrino 
C)  a proton, an electron, and an antineutrino 
D)  two X-ray photons, each with half the energy of the original gamma ray

Question 2

The Milky Way Galaxy is moving at about 600 km/s relative to the cosmic microwave background. How does this compare to Earth's speed in its orbit and to the speed of the solar system in its orbit around the galactic center?

Accepted Answer

A)  This speed is less than both the speed of the solar system and Earth's orbital speed. 
B)  This speed is greater than Earth's orbital speed but less than the solar system's speed. 
C)  This speed is greater than the solar system's speed but less than Earth's speed in its orbit. 
D)  This speed is greater than both Earth's speed in its orbit and the solar system's speed. 
A)  This speed is less than both the speed of the solar system and Earth's orbital speed. 
B)  This speed is greater than Earth's orbital speed but less than the solar system's speed. 
C)  This speed is greater than the solar system's speed but less than Earth's speed in its orbit. 
D)  This speed is greater than both Earth's speed in its orbit and the solar system's speed.

Question 3

In modern particle physics, the proton and the neutron are now thought to be composed of more fundamental particles called

Accepted Answer

A)  photons. 
B)  gluons. 
C)  neutrinos. 
D)  quarks. 
A)  photons. 
B)  gluons. 
C)  neutrinos. 
D)  quarks.

Question 4

Which of these statements does NOT correctly describe the universe at the era of recombination?

Accepted Answer

A)  The temperature of the universe was about 3 K. 
B)  The universe was about 380,000 years old. 
C)  The universe became transparent to radiation. 
D)  Electrons and protons combined to form neutral hydrogen atoms. 
A)  The temperature of the universe was about 3 K. 
B)  The universe was about 380,000 years old. 
C)  The universe became transparent to radiation. 
D)  Electrons and protons combined to form neutral hydrogen atoms.

Question 5

What are the particles that make up protons and neutrons?

Accepted Answer

A)  quarks 
B)  muons 
C)  gravitons 
D)  neutrinos 
A)  quarks 
B)  muons 
C)  gravitons 
D)  neutrinos

Question 6

An elliptical galaxy in Boötes (shown at the bottom of Figure 17-32 in the text) is at a distance of 1.6 billion ly and has an apparent recession speed of 39,000 km/s. What upper limit does this imply to the age of the universe? (Be careful with units.)

Accepted Answer

A)  0.47 billion years 
B)  12 million years 
C)  47 billion years 
D)  12 billion years 
A)  0.47 billion years 
B)  12 million years 
C)  47 billion years 
D)  12 billion years

Question 7

Which of these BEST describes the universe as envisioned by Isaac Newton?

Accepted Answer

A)  static and clumpy 
B)  expanding slowly and clumpy 
C)  expanding slowly and uniform 
D)  static and uniform 
A)  static and clumpy 
B)  expanding slowly and clumpy 
C)  expanding slowly and uniform 
D)  static and uniform

Question 8

If the cosmological constant exists, what physical effect is believed to create it?

Accepted Answer

A)  New matter is constantly being created in the expanding voids between superclusters of galaxies, and the energy released by this creation accelerates the expansion of the universe. 
B)  No one knows. The cosmological constant has been hypothesized to exist because astronomers see the universal expansion accelerating, but its source is still a mystery. 
C)  Energy released by nuclear reactions in stars and then emitted into space is heating the universe and accelerating its expansion. 
D)  Virtual particles that constantly appear and disappear add energy to empty space, and this vacuum energy provides a constant repulsive force that accelerates the universe. 
A)  New matter is constantly being created in the expanding voids between superclusters of galaxies, and the energy released by this creation accelerates the expansion of the universe. 
B)  No one knows. The cosmological constant has been hypothesized to exist because astronomers see the universal expansion accelerating, but its source is still a mystery. 
C)  Energy released by nuclear reactions in stars and then emitted into space is heating the universe and accelerating its expansion. 
D)  Virtual particles that constantly appear and disappear add energy to empty space, and this vacuum energy provides a constant repulsive force that accelerates the universe.

Question 9

Why did Einstein introduce his cosmological constant into the original equations for general relativity?

Accepted Answer

A)  The constant was necessary to make the solutions describe an expanding universe. 
B)  Experimental evidence at this time (before Hubble) suggested a static universe, and this constant was required to produce static solutions. 
C)  The constant represented the acceleration of gravity near Earth's surface, and it was necessary to make the nonrelativistic limit of the solutions compatible with Newton's results. 
D)  The constant represented the speed of light, and its inclusion was necessary to produce solutions that were compatible with the postulates of special relativity. 
A)  The constant was necessary to make the solutions describe an expanding universe. 
B)  Experimental evidence at this time (before Hubble) suggested a static universe, and this constant was required to produce static solutions. 
C)  The constant represented the acceleration of gravity near Earth's surface, and it was necessary to make the nonrelativistic limit of the solutions compatible with Newton's results. 
D)  The constant represented the speed of light, and its inclusion was necessary to produce solutions that were compatible with the postulates of special relativity.

Question 10

The Theory of Everything is the attempt to describe all four fundamental forces as aspects of a single unified force. The force that has proved to be the MOST difficult to incorporate into such a theory is

Accepted Answer

A)  gravity. 
B)  electromagnetism. 
C)  the weak nuclear force. 
D)  the strong nuclear force. 
A)  gravity. 
B)  electromagnetism. 
C)  the weak nuclear force. 
D)  the strong nuclear force.

Question 11

Which of these four periods of time describes this universe at present?

Accepted Answer

A)  inflationary period, in which the universe expands rapidly 
B)  era of recombination, in which electrons and protons combine to form hydrogen atoms 
C)  the Planck era, in which all four forces of nature are unified 
D)  period of confinement, in which quarks are unable to travel freely 
A)  inflationary period, in which the universe expands rapidly 
B)  era of recombination, in which electrons and protons combine to form hydrogen atoms 
C)  the Planck era, in which all four forces of nature are unified 
D)  period of confinement, in which quarks are unable to travel freely

Question 12

During the epoch of cosmic inflation, which of these properties of the universe changed rapidly?

Accepted Answer

A)  temperature 
B)  pressure 
C)  symmetries of the four forces 
D)  the separation of two points in spacetime 
A)  temperature 
B)  pressure 
C)  symmetries of the four forces 
D)  the separation of two points in spacetime

Question 13

The cosmological redshift of the light from very distant galaxies is caused by the

Accepted Answer

A)  rotation of the universe around its center (faster at greater distances from Earth). 
B)  expansion of space, stretching the photon's wavelength while the photon is traveling toward Earth. 
C)  absorption of blue light by interstellar dust between Earth and the galaxy so that only the red wavelengths reach Earth. 
D)  Doppler shift, in which the photon's wavelength is stretched by the galaxy's motion through space, away from Earth, while the photon is being emitted. 
A)  rotation of the universe around its center (faster at greater distances from Earth). 
B)  expansion of space, stretching the photon's wavelength while the photon is traveling toward Earth. 
C)  absorption of blue light by interstellar dust between Earth and the galaxy so that only the red wavelengths reach Earth. 
D)  Doppler shift, in which the photon's wavelength is stretched by the galaxy's motion through space, away from Earth, while the photon is being emitted.

Question 14

How many fundamental forces are known in science at the present time under normal conditions?

Accepted Answer

A)  four 
B)  five 
C)  three 
D)  six 
A)  four 
B)  five 
C)  three 
D)  six

Question 15

The view of the universe from Earth is limited because of what fundamental fact?

Accepted Answer

A)  The cosmological redshift has moved the light from very distant objects out of Earth's detectable range, making these objects invisible to observers. 
B)  The matter expanding into space from the Big Bang extends only so far since matter can travel only at or below the speed of light. 
C)  Light from objects farther away than a certain distance, defined by the travel time of light in the lifetime of the universe, has not yet reached Earth. 
D)  Intergalactic space contains absorbing material that blocks the view of more distant objects from Earth. 
A)  The cosmological redshift has moved the light from very distant objects out of Earth's detectable range, making these objects invisible to observers. 
B)  The matter expanding into space from the Big Bang extends only so far since matter can travel only at or below the speed of light. 
C)  Light from objects farther away than a certain distance, defined by the travel time of light in the lifetime of the universe, has not yet reached Earth. 
D)  Intergalactic space contains absorbing material that blocks the view of more distant objects from Earth.

Question 16

Suppose the expansion of the universe has been slowing since the Big Bang, and the value H0 is the Hubble constant that is appropriate to the universe today. What would this say about the age of the universe?

Accepted Answer

A)  The age should still be 1/H0 = 13.4 billion years. 
B)  The age would be less than 13.4 billion years. 
C)  The age would be greater than 13.4 billion years. 
D)  It is not possible to answer the question based only on this information. 
A)  The age should still be 1/H0 = 13.4 billion years. 
B)  The age would be less than 13.4 billion years. 
C)  The age would be greater than 13.4 billion years. 
D)  It is not possible to answer the question based only on this information.

Question 17

What order of events do cosmologists predict in the early universe, from earlier to later?

Accepted Answer

A)  Planck time, Big Bang, inflation, formation of protons and neutrons 
B)  Big Bang, Planck time, formation of protons and neutrons, inflation 
C)  Big Bang, inflation, Planck time, formation of protons and neutrons 
D)  Big Bang, Planck time, inflation, formation of protons and neutrons 
A)  Planck time, Big Bang, inflation, formation of protons and neutrons 
B)  Big Bang, Planck time, formation of protons and neutrons, inflation 
C)  Big Bang, inflation, Planck time, formation of protons and neutrons 
D)  Big Bang, Planck time, inflation, formation of protons and neutrons

Question 18

The Planck era refers to the

Accepted Answer

A)  time at which the expanding universe became transparent to radiation. 
B)  time of extremely rapid inflation that started 10-35 s after the universe began. 
C)  first 10-43 s of time, when all four fundamental forces are believed to have been united. 
D)  present age of the universe as given by the Hubble law. 
A)  time at which the expanding universe became transparent to radiation. 
B)  time of extremely rapid inflation that started 10-35 s after the universe began. 
C)  first 10-43 s of time, when all four fundamental forces are believed to have been united. 
D)  present age of the universe as given by the Hubble law.

Question 19

Which scientist discovered that the equations he had derived predicted an expanding universe, then modified his equations to eliminate this expansion?

Accepted Answer

A)  Albert Einstein 
B)  Isaac Newton 
C)  Stephen Hawking 
D)  Edwin Hubble 
A)  Albert Einstein 
B)  Isaac Newton 
C)  Stephen Hawking 
D)  Edwin Hubble

Question 20

The isotropy of the cosmic microwave background radiation (same temperature in all directions) indicates that

Accepted Answer

A)  the universe had an early period of inflation in which regions initially in equilibrium were carried to huge separations from each other. 
B)  the universe did not begin to expand significantly until after the era of recombination. 
C)  regions that appear to observers to be on opposite sides of the visible universe are in fact in close contact with each other. 
D)  the universe has always been dominated by matter. 
A)  the universe had an early period of inflation in which regions initially in equilibrium were carried to huge separations from each other. 
B)  the universe did not begin to expand significantly until after the era of recombination. 
C)  regions that appear to observers to be on opposite sides of the visible universe are in fact in close contact with each other. 
D)  the universe has always been dominated by matter.

When a gamma-ray photon undergoes pair production, what is one possibility for the final products?

The Milky Way Galaxy is moving at about 600 km/s relative to the cosmic microwave background. How does this compare to Earth's speed in its orbit and to the speed of the solar system in its orbit around the galactic center?

In modern particle physics, the proton and the neutron are now thought to be composed of more fundamental particles called

Which of these statements does NOT correctly describe the universe at the era of recombination?

What are the particles that make up protons and neutrons?

An elliptical galaxy in Boötes (shown at the bottom of Figure 17-32 in the text) is at a distance of 1.6 billion ly and has an apparent recession speed of 39,000 km/s. What upper limit does this imply to the age of the universe? (Be careful with units.)

Which of these BEST describes the universe as envisioned by Isaac Newton?

If the cosmological constant exists, what physical effect is believed to create it?

Why did Einstein introduce his cosmological constant into the original equations for general relativity?

The Theory of Everything is the attempt to describe all four fundamental forces as aspects of a single unified force. The force that has proved to be the MOST difficult to incorporate into such a theory is

Which of these four periods of time describes this universe at present?

During the epoch of cosmic inflation, which of these properties of the universe changed rapidly?

The cosmological redshift of the light from very distant galaxies is caused by the

How many fundamental forces are known in science at the present time under normal conditions?

The view of the universe from Earth is limited because of what fundamental fact?

Suppose the expansion of the universe has been slowing since the Big Bang, and the value H₀ is the Hubble constant that is appropriate to the universe today. What would this say about the age of the universe?

What order of events do cosmologists predict in the early universe, from earlier to later?

The Planck era refers to the

Which scientist discovered that the equations he had derived predicted an expanding universe, then modified his equations to eliminate this expansion?

The isotropy of the cosmic microwave background radiation (same temperature in all directions) indicates that

Discovering the Night Sky

Gravitation and the Motion of the Planets

Light and Telescopes

Atomic Physics and Spectra

Exoplanets and the Formation of Planetary Systems

Formation of the Solar System

Earth and the Moon

The Other Terrestrial Planets

The Outer Planets

Vagabonds of the Solar System

The Sun: Our Extraordinary Star

Characterizing Stars

The Lives of Stars From Birth Through Middle Age

The Death of Stars

Black Holes: Matters of Gravity

The Milky Way Galaxy

Galaxies

Quasars and Other Active Galaxies

Astrobiology

Filters

Exam 19: Cosmology

When a gamma-ray photon undergoes pair production, what is one possibility for the final products?

The Milky Way Galaxy is moving at about 600 km/s relative to the cosmic microwave background. How does this compare to Earth's speed in its orbit and to the speed of the solar system in its orbit around the galactic center?

In modern particle physics, the proton and the neutron are now thought to be composed of more fundamental particles called

Which of these statements does NOT correctly describe the universe at the era of recombination?

What are the particles that make up protons and neutrons?

An elliptical galaxy in Boötes (shown at the bottom of Figure 17-32 in the text) is at a distance of 1.6 billion ly and has an apparent recession speed of 39,000 km/s. What upper limit does this imply to the age of the universe? (Be careful with units.)

Which of these BEST describes the universe as envisioned by Isaac Newton?

If the cosmological constant exists, what physical effect is believed to create it?

Why did Einstein introduce his cosmological constant into the original equations for general relativity?

The Theory of Everything is the attempt to describe all four fundamental forces as aspects of a single unified force. The force that has proved to be the MOST difficult to incorporate into such a theory is

Which of these four periods of time describes this universe at present?

During the epoch of cosmic inflation, which of these properties of the universe changed rapidly?

The cosmological redshift of the light from very distant galaxies is caused by the

How many fundamental forces are known in science at the present time under normal conditions?

The view of the universe from Earth is limited because of what fundamental fact?

Suppose the expansion of the universe has been slowing since the Big Bang, and the value H0 is the Hubble constant that is appropriate to the universe today. What would this say about the age of the universe?

What order of events do cosmologists predict in the early universe, from earlier to later?

The Planck era refers to the

Which scientist discovered that the equations he had derived predicted an expanding universe, then modified his equations to eliminate this expansion?

The isotropy of the cosmic microwave background radiation (same temperature in all directions) indicates that

Discovering the Night Sky

Gravitation and the Motion of the Planets

Light and Telescopes

Atomic Physics and Spectra

Exoplanets and the Formation of Planetary Systems

Formation of the Solar System

Earth and the Moon

The Other Terrestrial Planets

The Outer Planets

Vagabonds of the Solar System

The Sun: Our Extraordinary Star

Characterizing Stars

The Lives of Stars From Birth Through Middle Age

The Death of Stars

Black Holes: Matters of Gravity

The Milky Way Galaxy

Galaxies

Quasars and Other Active Galaxies

Astrobiology

Filters

Suppose the expansion of the universe has been slowing since the Big Bang, and the value H₀ is the Hubble constant that is appropriate to the universe today. What would this say about the age of the universe?