Question 1

Which of these cosmological problems is "dark energy" believed to solve?

Accepted Answer

A)  Why is the universe's expansion accelerating? 
B)  Why did the universe suddenly inflate during the Big Bang? 
C)  Why is the temperature of the cosmic background radiation so smooth (isotropic) around the sky? 
D)  Why is the night sky dark? 
A)  Why is the universe's expansion accelerating? 
B)  Why did the universe suddenly inflate during the Big Bang? 
C)  Why is the temperature of the cosmic background radiation so smooth (isotropic) around the sky? 
D)  Why is the night sky dark? A

Question 2

Why does the cosmic microwave background appear to be slightly warmer in one direction in the sky and slightly cooler in the opposite direction?

Accepted Answer

A)  The warmer direction is the direction in which the Big Bang occurred; hence, astronomers are seeing the remnant of the explosion in this direction. 
B)  The universe is younger in one direction and therefore warmer. 
C)  The radiation in one direction is Doppler-shifted to shorter wavelengths by Earth's motion in space and to longer wavelengths in the other direction. 
D)  Large amounts of matter in the warmer direction have focused the radiation slightly by gravitational lensing, making this direction appear hotter. 
A)  The warmer direction is the direction in which the Big Bang occurred; hence, astronomers are seeing the remnant of the explosion in this direction. 
B)  The universe is younger in one direction and therefore warmer. 
C)  The radiation in one direction is Doppler-shifted to shorter wavelengths by Earth's motion in space and to longer wavelengths in the other direction. 
D)  Large amounts of matter in the warmer direction have focused the radiation slightly by gravitational lensing, making this direction appear hotter. C

Question 3

On the basis of recent results from very bright and very distant Type Ia supernovae, which of these statements BEST characterizes the past and present motion of clusters of galaxies?

Accepted Answer

A)  The universe is "flat," with a decelerating rate of expansion. 
B)  The universe is "open," with a constant rate of expansion given by the Hubble law. 
C)  The universe is "closed," with a decelerating rate of expansion. 
D)  The universe is "flat," with an accelerating rate of expansion. 
A)  The universe is "flat," with a decelerating rate of expansion. 
B)  The universe is "open," with a constant rate of expansion given by the Hubble law. 
C)  The universe is "closed," with a decelerating rate of expansion. 
D)  The universe is "flat," with an accelerating rate of expansion. D

Question 4

When the intensity of the cosmic microwave background radiation is plotted against wavelength, what is the shape of the resulting curve?

Accepted Answer

A)  emission lines, strongest and most densely concentrated in the microwave region 
B)  composite of many overlapping blackbody curves from gas clouds of different temperatures peaking in the microwaves 
C)  blackbody curve modified by many deep, overlapping absorption lines and several emission lines 
D)  essentially perfect blackbody spectrum peaking in the microwave region 
A)  emission lines, strongest and most densely concentrated in the microwave region 
B)  composite of many overlapping blackbody curves from gas clouds of different temperatures peaking in the microwaves 
C)  blackbody curve modified by many deep, overlapping absorption lines and several emission lines 
D)  essentially perfect blackbody spectrum peaking in the microwave region

Question 5

In cosmology, what is the "inflationary period"?

Accepted Answer

A)  the period when the cost of living rose faster than astronomers' salaries 
B)  the first 500,000 years of the life of the universe, when matter and radiation interacted vigorously 
C)  the period of universal expansion from the Big Bang to the present 
D)  the short period of extremely rapid expansion when the universe was very young 
A)  the period when the cost of living rose faster than astronomers' salaries 
B)  the first 500,000 years of the life of the universe, when matter and radiation interacted vigorously 
C)  the period of universal expansion from the Big Bang to the present 
D)  the short period of extremely rapid expansion when the universe was very young

Question 6

How many quarks are there in a proton or a neutron?

Accepted Answer

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

Question 7

A comparison of an elliptical galaxy and a spiral galaxy of the same mass a billion years after both began formation would show that

Accepted Answer

A)  they should each have about the same number of stars. 
B)  the elliptical galaxy will have formed more stars than the spiral galaxy. 
C)  the spiral galaxy will have formed more stars than the elliptical. 
D)  neither galaxy will have formed any stars during the first billion years. 
A)  they should each have about the same number of stars. 
B)  the elliptical galaxy will have formed more stars than the spiral galaxy. 
C)  the spiral galaxy will have formed more stars than the elliptical. 
D)  neither galaxy will have formed any stars during the first billion years.

Question 8

How do the youngest, most distant galaxies compare with the older galaxies astronomers view nearby today?

Accepted Answer

A)  The youngest galaxies are bluer and brighter than the older ones. 
B)  The youngest galaxies have the same color as the older ones but are significantly brighter. 
C)  There is no observable difference between the youngest galaxies and the older ones. 
D)  The youngest galaxies are redder and fainter than the older ones. 
A)  The youngest galaxies are bluer and brighter than the older ones. 
B)  The youngest galaxies have the same color as the older ones but are significantly brighter. 
C)  There is no observable difference between the youngest galaxies and the older ones. 
D)  The youngest galaxies are redder and fainter than the older ones.

Question 9

The forces of gravity and electromagnetism are long-range forces, extending in principle from their source (mass and electric charge, respectively) to infinity. Why is it that, in the universe, only gravity extends to infinity, whereas electromagnetic forces are much more limited in extent?

Accepted Answer

A)  Gravity and electromagnetism are one and the same force, with electromagnetic effects extending over limited spatial ranges and transforming into gravitational forces at large distances from matter. 
B)  Electromagnetic forces from charged particles will move other charged particles around to produce a uniform charge distribution and therefore zero electromagnetic forces, whereas gravity concentrates mass and enhances the overall gravity force. 
C)  Electromagnetic forces from positive charges are canceled by negative charges, whereas there are no negative "masses" to cancel the gravitational force. 
D)  All atoms are electrically neutral, so in reality the electromagnetic force never reaches beyond the size of an atomic nucleus. 
A)  Gravity and electromagnetism are one and the same force, with electromagnetic effects extending over limited spatial ranges and transforming into gravitational forces at large distances from matter. 
B)  Electromagnetic forces from charged particles will move other charged particles around to produce a uniform charge distribution and therefore zero electromagnetic forces, whereas gravity concentrates mass and enhances the overall gravity force. 
C)  Electromagnetic forces from positive charges are canceled by negative charges, whereas there are no negative "masses" to cancel the gravitational force. 
D)  All atoms are electrically neutral, so in reality the electromagnetic force never reaches beyond the size of an atomic nucleus.

Question 10

Which parameter of the present universe is considered to be critical in determining the ultimate fate of the universe?

Accepted Answer

A)  amount of mass in black holes in the universe 
B)  number of neutrinos in the universe 
C)  amount of matter and energy in the universe 
D)  number of photons of radiation in the universe 
A)  amount of mass in black holes in the universe 
B)  number of neutrinos in the universe 
C)  amount of matter and energy in the universe 
D)  number of photons of radiation in the universe

Question 11

The future of the overall universe, in terms of its ultimate evolution and whether it will expand forever or eventually contract again, depends MOST directly on which of these parameters?

Accepted Answer

A)  present volume of the universe 
B)  amount of matter and energy within the universe 
C)  intensity of cosmic microwave background radiation 
D)  temperature of the gas within the universe 
A)  present volume of the universe 
B)  amount of matter and energy within the universe 
C)  intensity of cosmic microwave background radiation 
D)  temperature of the gas within the universe

Question 12

Opposite sides of the universe have the same temperature, yet according to the standard Big Bang theory, these points are too far apart for light to have traveled from one to the other in the age of the universe; that is, they cannot have exchanged heat to even out their temperature. Why, then, do they have the same temperature?

Accepted Answer

A)  Light (and heat) could travel much faster in the early universe, allowing them to exchange heat while the universe was young. 
B)  The expansion of the universe has always been the same everywhere; therefore, all parts of the universe have the same temperature regardless of whether they have ever exchanged heat or not. 
C)  It is pure coincidence that opposite sides of the universe have the same temperature. 
D)  Opposite sides of the universe were originally close together and evened out their temperature, and then a rapid inflation of the universe carried them far apart. 
A)  Light (and heat) could travel much faster in the early universe, allowing them to exchange heat while the universe was young. 
B)  The expansion of the universe has always been the same everywhere; therefore, all parts of the universe have the same temperature regardless of whether they have ever exchanged heat or not. 
C)  It is pure coincidence that opposite sides of the universe have the same temperature. 
D)  Opposite sides of the universe were originally close together and evened out their temperature, and then a rapid inflation of the universe carried them far apart.

Question 13

The greatest support for the Big Bang theory of cosmology came from the discovery of

Accepted Answer

A)  the cosmic microwave background. 
B)  the cosmic neutrino background. 
C)  isotropy in the universe. 
D)  homogeneity in the universe. 
A)  the cosmic microwave background. 
B)  the cosmic neutrino background. 
C)  isotropy in the universe. 
D)  homogeneity in the universe.

Question 14

Which of these statements correctly describes cosmologists' current state of knowledge about the future expansion of the universe?

Accepted Answer

A)  The amount of matter (both visible and dark) is only 1/3 the amount needed to halt expansion, so the expansion will continue to slow down but will never stop. 
B)  The amount of matter (both visible and dark) is only 1/3 the amount needed to halt expansion, and there is strong evidence of a previously unknown form of energy that acts to accelerate the expansion. 
C)  The amount of matter (both visible and dark) is exactly the right amount needed to halt expansion after an infinite amount of time has gone by. 
D)  The amount of matter (both visible and dark) is 3 times the amount needed to halt expansion, so the expansion will eventually stop and the universe will begin to collapse. 
A)  The amount of matter (both visible and dark) is only 1/3 the amount needed to halt expansion, so the expansion will continue to slow down but will never stop. 
B)  The amount of matter (both visible and dark) is only 1/3 the amount needed to halt expansion, and there is strong evidence of a previously unknown form of energy that acts to accelerate the expansion. 
C)  The amount of matter (both visible and dark) is exactly the right amount needed to halt expansion after an infinite amount of time has gone by. 
D)  The amount of matter (both visible and dark) is 3 times the amount needed to halt expansion, so the expansion will eventually stop and the universe will begin to collapse.

Question 15

The cosmic background radiation that was left over after the Big Bang of the universe and that pervades all observable space has an effective blackbody temperature of approximately

Accepted Answer

A)  273 K. 
B)  0 K. 
C)  10 K. 
D)  3 K. 
A)  273 K. 
B)  0 K. 
C)  10 K. 
D)  3 K.

Question 16

Who first proposed that the observed motion of galaxies away from Earth implied the existence of a radio background pervading the universe?

Accepted Answer

A)  Robert Dicke 
B)  George Gamow 
C)  Fred Hoyle 
D)  Edwin Hubble 
A)  Robert Dicke 
B)  George Gamow 
C)  Fred Hoyle 
D)  Edwin Hubble

Question 17

What would the age of the universe be if the Hubble constant, H0, is 60 km/s/Mpc?

Accepted Answer

A)  15.0 billion years 
B)  16.6 billion years 
C)  60 billion years 
D)  11.1 billion years 
A)  15.0 billion years 
B)  16.6 billion years 
C)  60 billion years 
D)  11.1 billion years

Question 18

In a primordial, pregalactic gas cloud, what is believed to have been the MOST important condition that caused the cloud to become a spiral galaxy (as opposed to some other type of galaxy)?

Accepted Answer

A)  The cloud started off with a lot of dust and heavy elements. 
B)  The initial rate of star formation was high. 
C)  The cloud started off flattened and disk-shaped before it collapsed. 
D)  The initial rate of star formation was low. 
A)  The cloud started off with a lot of dust and heavy elements. 
B)  The initial rate of star formation was high. 
C)  The cloud started off flattened and disk-shaped before it collapsed. 
D)  The initial rate of star formation was low.

Question 19

Recent results from very bright supernovae in very distant galaxies indicate that the expansion of the universe

Accepted Answer

A)  has now stopped and the universe will shortly begin to contract again toward a Big Crunch. 
B)  is decelerating (slowing down). 
C)  is continuing at a constant rate and has done so since just after the Big Bang. 
D)  is accelerating (speeding up). 
A)  has now stopped and the universe will shortly begin to contract again toward a Big Crunch. 
B)  is decelerating (slowing down). 
C)  is continuing at a constant rate and has done so since just after the Big Bang. 
D)  is accelerating (speeding up).

Question 20

Which of these statements is a correct description of the expansion of the universe?

Accepted Answer

A)  Spacetime is something real, with galaxies inside it; as spacetime expands, the galaxies (or superclusters of galaxies) are carried along by the expansion. 
B)  Space is a vacuum, but the vacuum has real properties; as galaxies (or superclusters of galaxies) hurtle outward, the expansion is gradually slowing down by the resistance of space to the passage of the galaxies. 
C)  Spacetime is static, but dark matter, which is concentrated in the outer part of the universe, pulls outward on the galaxies. 
D)  Space is a vacuum, which is really nothing at all; the galaxies (or superclusters of galaxies) are hurtling outward through this nothingness. 
A)  Spacetime is something real, with galaxies inside it; as spacetime expands, the galaxies (or superclusters of galaxies) are carried along by the expansion. 
B)  Space is a vacuum, but the vacuum has real properties; as galaxies (or superclusters of galaxies) hurtle outward, the expansion is gradually slowing down by the resistance of space to the passage of the galaxies. 
C)  Spacetime is static, but dark matter, which is concentrated in the outer part of the universe, pulls outward on the galaxies. 
D)  Space is a vacuum, which is really nothing at all; the galaxies (or superclusters of galaxies) are hurtling outward through this nothingness.

Which of these cosmological problems is "dark energy" believed to solve?

Why does the cosmic microwave background appear to be slightly warmer in one direction in the sky and slightly cooler in the opposite direction?

On the basis of recent results from very bright and very distant Type Ia supernovae, which of these statements BEST characterizes the past and present motion of clusters of galaxies?

When the intensity of the cosmic microwave background radiation is plotted against wavelength, what is the shape of the resulting curve?

In cosmology, what is the "inflationary period"?

How many quarks are there in a proton or a neutron?

A comparison of an elliptical galaxy and a spiral galaxy of the same mass a billion years after both began formation would show that

How do the youngest, most distant galaxies compare with the older galaxies astronomers view nearby today?

The forces of gravity and electromagnetism are long-range forces, extending in principle from their source (mass and electric charge, respectively) to infinity. Why is it that, in the universe, only gravity extends to infinity, whereas electromagnetic forces are much more limited in extent?

Which parameter of the present universe is considered to be critical in determining the ultimate fate of the universe?

The future of the overall universe, in terms of its ultimate evolution and whether it will expand forever or eventually contract again, depends MOST directly on which of these parameters?

The greatest support for the Big Bang theory of cosmology came from the discovery of

Which of these statements correctly describes cosmologists' current state of knowledge about the future expansion of the universe?

The cosmic background radiation that was left over after the Big Bang of the universe and that pervades all observable space has an effective blackbody temperature of approximately

Who first proposed that the observed motion of galaxies away from Earth implied the existence of a radio background pervading the universe?

What would the age of the universe be if the Hubble constant, H₀, is 60 km/s/Mpc?

In a primordial, pregalactic gas cloud, what is believed to have been the MOST important condition that caused the cloud to become a spiral galaxy (as opposed to some other type of galaxy)?

Recent results from very bright supernovae in very distant galaxies indicate that the expansion of the universe

Which of these statements is a correct description of the expansion of the universe?

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

Which of these cosmological problems is "dark energy" believed to solve?

Why does the cosmic microwave background appear to be slightly warmer in one direction in the sky and slightly cooler in the opposite direction?

On the basis of recent results from very bright and very distant Type Ia supernovae, which of these statements BEST characterizes the past and present motion of clusters of galaxies?

When the intensity of the cosmic microwave background radiation is plotted against wavelength, what is the shape of the resulting curve?

In cosmology, what is the "inflationary period"?

How many quarks are there in a proton or a neutron?

A comparison of an elliptical galaxy and a spiral galaxy of the same mass a billion years after both began formation would show that

How do the youngest, most distant galaxies compare with the older galaxies astronomers view nearby today?

The forces of gravity and electromagnetism are long-range forces, extending in principle from their source (mass and electric charge, respectively) to infinity. Why is it that, in the universe, only gravity extends to infinity, whereas electromagnetic forces are much more limited in extent?

Which parameter of the present universe is considered to be critical in determining the ultimate fate of the universe?

The future of the overall universe, in terms of its ultimate evolution and whether it will expand forever or eventually contract again, depends MOST directly on which of these parameters?

The greatest support for the Big Bang theory of cosmology came from the discovery of

Which of these statements correctly describes cosmologists' current state of knowledge about the future expansion of the universe?

The cosmic background radiation that was left over after the Big Bang of the universe and that pervades all observable space has an effective blackbody temperature of approximately

Who first proposed that the observed motion of galaxies away from Earth implied the existence of a radio background pervading the universe?

What would the age of the universe be if the Hubble constant, H0, is 60 km/s/Mpc?

In a primordial, pregalactic gas cloud, what is believed to have been the MOST important condition that caused the cloud to become a spiral galaxy (as opposed to some other type of galaxy)?

Recent results from very bright supernovae in very distant galaxies indicate that the expansion of the universe

Which of these statements is a correct description of the expansion of the universe?

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

What would the age of the universe be if the Hubble constant, H₀, is 60 km/s/Mpc?