Question 1

The region around a black hole where everything is trapped, and nothing can get out to interact with the rest of the universe, is called

Accepted Answer

A)  the singularity 
B)  the neutron star radius 
C)  the gravitational redshift zone 
D)  the event horizon 
E)  day-time television 
A)  the singularity 
B)  the neutron star radius 
C)  the gravitational redshift zone 
D)  the event horizon 
E)  day-time television

Question 2

Suppose each of the following objects could collapse into a black hole. Each black hole would have a sphere around it that is the limit for escape -- once you are inside this region, you cannot get away. For which object would this region be the largest in diameter?

Accepted Answer

A)  a star with the mass of our Sun 
B)  a planet like Jupiter 
C)  a star that was type O when it was on the main sequence 
D)  an entire cluster of stars (with about 150 stars in it) 
E)  an entire galaxy of stars (with about a billion stars in it) 
A)  a star with the mass of our Sun 
B)  a planet like Jupiter 
C)  a star that was type O when it was on the main sequence 
D)  an entire cluster of stars (with about 150 stars in it) 
E)  an entire galaxy of stars (with about a billion stars in it)

Question 3

To predict whether a star will ultimately become a black hole, what is the key property of the star we should look at?

Accepted Answer

A)  mass 
B)  surface temperature 
C)  color 
D)  distance 
E)  diameter 
A)  mass 
B)  surface temperature 
C)  color 
D)  distance 
E)  diameter

Question 4

According to the general theory of relativity, the presence of mass

Accepted Answer

A)  causes motion at the speed of light squared 
B)  is equivalent to the presence of light 
C)  causes curved paths to straighten out until they are exactly straight lines 
D)  causes a curvature (or warping) of spacetime 
E)  will cause a black hole to form, unless there is motion 
A)  causes motion at the speed of light squared 
B)  is equivalent to the presence of light 
C)  causes curved paths to straighten out until they are exactly straight lines 
D)  causes a curvature (or warping) of spacetime 
E)  will cause a black hole to form, unless there is motion

Question 5

According to Einstein's general theory of relativity, the stronger a star's gravity,

Accepted Answer

A)  the weaker its pull on another star will be 
B)  the slower time runs near it 
C)  the weaker the x-rays we see from it 
D)  the smaller the event horizon will be of the black hole it makes 
E)  the less space-time around it will be distorted 
A)  the weaker its pull on another star will be 
B)  the slower time runs near it 
C)  the weaker the x-rays we see from it 
D)  the smaller the event horizon will be of the black hole it makes 
E)  the less space-time around it will be distorted

Question 6

Which of the following statements about the way the mass of a white dwarf affects spacetime is correct?

Accepted Answer

A)  the white dwarf mass will attract light, and pull it in a curved path; spacetime is not affected 
B)  the white dwarf mass will curve spacetime; light has to follow that curvature 
C)  the white dwarf mass will not affect spacetime at all; only black holes affect spacetime 
D)  the white dwarf mass will have enough gravity to straighten out any curvature in spacetime; so spacetime near the white dwarf will be flat 
E)  since no experiments have ever tested Einstein's theory of general relativity, it is impossible to say what will happen
Section 24.3: Tests of General Relativity 
A)  the white dwarf mass will attract light, and pull it in a curved path; spacetime is not affected 
B)  the white dwarf mass will curve spacetime; light has to follow that curvature 
C)  the white dwarf mass will not affect spacetime at all; only black holes affect spacetime 
D)  the white dwarf mass will have enough gravity to straighten out any curvature in spacetime; so spacetime near the white dwarf will be flat 
E)  since no experiments have ever tested Einstein's theory of general relativity, it is impossible to say what will happen
Section 24.3: Tests of General Relativity

Question 7

In the far future, a starship becomes trapped inside the event horizon of a black hole. Although the crew discovers that their ship cannot out, they at least want to send a message to other ships in the area to stay away from the danger zone. If they send out a message in the form of a radio wave, what will be its fate?

Accepted Answer

A)  the message will emerge from the event horizon with a huge gravitational redshift 
B)  although the radio wave will emerge from the event horizon, all the information in the message will be garbled 
C)  the radio wave will become a gamma ray by the time it emerges from the event horizon 
D)  the radio wave will only emerge from the event horizon if it is moving in the direction of the magnetic north and south pole of the star that formed the black hole 
E)  the message will never emerge from the event horizon 
A)  the message will emerge from the event horizon with a huge gravitational redshift 
B)  although the radio wave will emerge from the event horizon, all the information in the message will be garbled 
C)  the radio wave will become a gamma ray by the time it emerges from the event horizon 
D)  the radio wave will only emerge from the event horizon if it is moving in the direction of the magnetic north and south pole of the star that formed the black hole 
E)  the message will never emerge from the event horizon

Question 8

Which of the following objects do many astronomers believe is a black hole?

Accepted Answer

A)  the nebula in Orion where new stars are seen to form (from dark dust clouds) 
B)  the Crab Nebula 
C)  Cygnus X-1 
D)  the open cluster called the Pleiades 
E)  Bayonne, New Jersey 
A)  the nebula in Orion where new stars are seen to form (from dark dust clouds) 
B)  the Crab Nebula 
C)  Cygnus X-1 
D)  the open cluster called the Pleiades 
E)  Bayonne, New Jersey

Question 9

When one member of a binary star system is a black hole, and astronomers detect flickering x-rays coming from the system, where are these x-rays usually coming from?

Accepted Answer

A)  from inside the black hole event horizon 
B)  from the photosphere of the companion star (the star that is not a black hole) 
C)  from the singularity 
D)  from a disk of material around the black hole (material that has been pulled from the companion star and is falling toward the black hole) 
E)  from a distant galaxy that just happens to lie behind the black hole system (astronomers discovered that such x-rays have nothing to do with the black hole) 
A)  from inside the black hole event horizon 
B)  from the photosphere of the companion star (the star that is not a black hole) 
C)  from the singularity 
D)  from a disk of material around the black hole (material that has been pulled from the companion star and is falling toward the black hole) 
E)  from a distant galaxy that just happens to lie behind the black hole system (astronomers discovered that such x-rays have nothing to do with the black hole)

Question 10

The equivalence principle (principle of equivalence) says that

Accepted Answer

A)  the amount of energy released by fusion is equivalent to the amount of mass that is lost 
B)  gravity is equivalent the strong nuclear force is inside any nucleus 
C)  the effects of gravity are equivalent to the effects of acceleration 
D)  far away from a black hole, its pull is equivalent to the pull of the star that it formed from 
E)  the event horizon of a black hole is equivalent to the place where things are forever trapped 
A)  the amount of energy released by fusion is equivalent to the amount of mass that is lost 
B)  gravity is equivalent the strong nuclear force is inside any nucleus 
C)  the effects of gravity are equivalent to the effects of acceleration 
D)  far away from a black hole, its pull is equivalent to the pull of the star that it formed from 
E)  the event horizon of a black hole is equivalent to the place where things are forever trapped

Question 11

When scientists say that "black holes have no hair", what do they mean?

Accepted Answer

A)  that the event horizon of a black hole is very smooth and does not have parts that jut out 
B)  that if you threw something toward a black hole (a rabbit, say) it would quickly be ripped apart into smaller pieces 
C)  that time near a black hole slows down so much our hair would not grow at a normal rate 
D)  that once a black hole forms, very little information can be extracted from it about the material that is now inside 
E)  no one knows what this means; regular people are not meant to figure out some of the weird things physicists say about black holes 
A)  that the event horizon of a black hole is very smooth and does not have parts that jut out 
B)  that if you threw something toward a black hole (a rabbit, say) it would quickly be ripped apart into smaller pieces 
C)  that time near a black hole slows down so much our hair would not grow at a normal rate 
D)  that once a black hole forms, very little information can be extracted from it about the material that is now inside 
E)  no one knows what this means; regular people are not meant to figure out some of the weird things physicists say about black holes

Question 12

The first time that astronomers observed both gravitational waves and electro-magnetic waves from the same event, what they were observing was:

Accepted Answer

A)  a supernova explosion in one of the closest galaxies to us 
B)  the spiraling toward each other of two neutron stars 
C)  a binary star system where a giant star is overloading a white dwarf with too much material 
D)  the merger of two black holes with masses dozens of times the mass of our Sun 
E)  the collapse of an entire cluster of stars into one big black hole 
A)  a supernova explosion in one of the closest galaxies to us 
B)  the spiraling toward each other of two neutron stars 
C)  a binary star system where a giant star is overloading a white dwarf with too much material 
D)  the merger of two black holes with masses dozens of times the mass of our Sun 
E)  the collapse of an entire cluster of stars into one big black hole

Question 13

From which of the following will a wave of light show the greatest gravitational redshift:

Accepted Answer

A)  a white dwarf 
B)  a giant planet like Jupiter 
C)  Earth 
D)  the Sun 
E)  a spaceship in empty space 
A)  a white dwarf 
B)  a giant planet like Jupiter 
C)  Earth 
D)  the Sun 
E)  a spaceship in empty space

Exam 24: Black Holes and Curved Space-Time

The region around a black hole where everything is trapped, and nothing can get out to interact with the rest of the universe, is called

Suppose each of the following objects could collapse into a black hole. Each black hole would have a sphere around it that is the limit for escape -- once you are inside this region, you cannot get away. For which object would this region be the largest in diameter?

To predict whether a star will ultimately become a black hole, what is the key property of the star we should look at?

According to the general theory of relativity, the presence of mass

According to Einstein's general theory of relativity, the stronger a star's gravity,

Which of the following statements about the way the mass of a white dwarf affects spacetime is correct?

Which of the following objects do many astronomers believe is a black hole?

When one member of a binary star system is a black hole, and astronomers detect flickering x-rays coming from the system, where are these x-rays usually coming from?

The equivalence principle (principle of equivalence) says that

When scientists say that "black holes have no hair", what do they mean?

The first time that astronomers observed both gravitational waves and electro-magnetic waves from the same event, what they were observing was:

From which of the following will a wave of light show the greatest gravitational redshift:

Science and the Universe: a Brief Tour

Observing the Sky: the Birth of Astronomy

Orbits and Gravity

Earth, Moon, and Sky

Radiation and Spectra

Astronomical Instruments

Other Worlds: an Introduction to the Solar System

Earth As a Planet

Cratered Worlds: the Moon and Mercury

Earthlike Planets: Venus and Mars

The Giant Planets

Rings, Moons, and Pluto

Comets and Asteroids: Debris of the Solar System

Cosmic Samples and the Origin of the Solar System

The Sun: a Garden-Variety Star

The Sun: a Nuclear Powerhouse

Analyzing Starlight

The Stars: a Celestial Census

Celestial Distances

Between the Stars

The Birth of Stars and the Discovery of Planets Outside the Solar System

Stars From Adolescence to Old Age

The Death of Stars

The Milky Way Galaxy

Galaxies

Active Galaxies, Quasars, and Supermassive Black Holes

The Evolution and Distribution of Galaxies

The Big Bang

Life in the Universe

Filters