Question 1

What is gravitational lensing? According to general relativity,why does it occur?

Accepted Answer

It is the distortion of the appearance of distant objects due to gravity and occurs because their light passes through regions of space that are curved.

Question 2

Which of the following correctly describes the relationship between Newton's theory of gravity and general relativity?

Accepted Answer

A) Newton's theory of gravity is now known to be false,and we were previously misled to think it was true by measurement errors. 
B) Newton's theory of gravity and general relativity give the same answers,but the former tells us to think of gravity as a force and the latter tells us to think of gravity as curvature of spacetime. 
C) Newton's theory of gravity is an approximation to general relativity that works when gravity is relatively weak,but breaks down when gravity is strong. 
D) General relativity applies at the sub-atomic level,but Newton's theory of gravity does not. 
A) Newton's theory of gravity is now known to be false,and we were previously misled to think it was true by measurement errors. 
B) Newton's theory of gravity and general relativity give the same answers,but the former tells us to think of gravity as a force and the latter tells us to think of gravity as curvature of spacetime. 
C) Newton's theory of gravity is an approximation to general relativity that works when gravity is relatively weak,but breaks down when gravity is strong. 
D) General relativity applies at the sub-atomic level,but Newton's theory of gravity does not. C

Question 3

As predicted by general relativity,time runs slightly slower at the peak of Mount Everest than it does at sea level.

Accepted Answer

A) True 
 B)False  False

Question 4

If you draw a spacetime diagram,the worldline of an object that is stationary in your reference frame is

Accepted Answer

A) vertical. 
B) horizontal. 
C) slanted. 
D) curved. 
E) a circle. 
A) vertical. 
B) horizontal. 
C) slanted. 
D) curved. 
E) a circle.

Question 5

What do we mean by hyperspace?

Accepted Answer

A) It is another word for spacetime. 
B) It is a space through which it is possible to travel very fast. 
C) It is a space with a hyperbolic geometry. 
D) Any space with more than three dimensions. 
A) It is another word for spacetime. 
B) It is a space through which it is possible to travel very fast. 
C) It is a space with a hyperbolic geometry. 
D) Any space with more than three dimensions.

Question 6

In your own words,explain what we mean by spacetime.

Accepted Answer

It is the combination of space

Question 7

If your worldline is following the straightest possible path through spacetime,then

Accepted Answer

A) you will be weightless. 
B) you will feel heavier than your normal weight. 
C) you must be accelerating. 
D) you must be traveling at constant velocity. 
A) you will be weightless. 
B) you will feel heavier than your normal weight. 
C) you must be accelerating. 
D) you must be traveling at constant velocity.

Question 8

Although many scientists believe general relativity to be correct,there is no experimental evidence supporting the predictions this theory makes about time.

Accepted Answer

A) True 
 B)False

Question 9

What do we mean by the event horizon of a black hole?

Accepted Answer

A) It is the center of the black hole. 
B) It is the "bottomless pit" of the black hole. 
C) It is the place where time begins to slow down as you approach a black hole. 
D) It is the boundary within which events in the black hole cannot influence events in the outside universe. 
A) It is the center of the black hole. 
B) It is the "bottomless pit" of the black hole. 
C) It is the place where time begins to slow down as you approach a black hole. 
D) It is the boundary within which events in the black hole cannot influence events in the outside universe.

Question 10

Space is different for different observers.Time is different for different observers.Spacetime is the same for everyone.

Accepted Answer

A) True 
 B)False

Question 11

According to general relativity,how is time affected by gravity?

Accepted Answer

A) Time is not affected by gravity. 
B) Time is affected by gravity,but not in a predictable way. 
C) Time is stopped by any gravitational field. 
D) Time runs faster in stronger gravitational fields. 
E) Time runs slower in stronger gravitational fields. 
A) Time is not affected by gravity. 
B) Time is affected by gravity,but not in a predictable way. 
C) Time is stopped by any gravitational field. 
D) Time runs faster in stronger gravitational fields. 
E) Time runs slower in stronger gravitational fields.

Question 12

Suppose you claim that you are feeling the effects of a gravitational field.How can you explain the fact that Al is weightless?

Accepted Answer

A) She is weightless because she is moving at constant velocity. 
B) She is weightless because she is in a free-float frame. 
C) She is weightless because she is in free-fall. 
D) If you are in a gravitational field,then she cannot be weightless. 
A) She is weightless because she is moving at constant velocity. 
B) She is weightless because she is in a free-float frame. 
C) She is weightless because she is in free-fall. 
D) If you are in a gravitational field,then she cannot be weightless.

Question 13

Mercury's perihelion slowly precesses around the Sun by a bit less than 2° per century.This precession can be fully accounted for by Newton's theory of gravity,although general relativity also gives the same answer.

Accepted Answer

A) True 
 B)False

Question 14

In what way do observations of Mercury support Einstein's general theory of relativity?

Accepted Answer

A) Mercury's orbit slowly precesses in a way that matches the prediction of general relativity but disagrees with the prediction based on Newton's universal law of gravitation. 
B) Einstein discovered that time runs slower on Mercury than on Earth,as his theory predicted. 
C) Einstein was able to explain the fact that Mercury orbits the Sun exactly twice for every three rotations,and Newton's theory of gravity cannot account for this. 
D) We can see that Mercury lies deeper in the spacetime bowl that surrounds the Sun than does Earth. 
A) Mercury's orbit slowly precesses in a way that matches the prediction of general relativity but disagrees with the prediction based on Newton's universal law of gravitation. 
B) Einstein discovered that time runs slower on Mercury than on Earth,as his theory predicted. 
C) Einstein was able to explain the fact that Mercury orbits the Sun exactly twice for every three rotations,and Newton's theory of gravity cannot account for this. 
D) We can see that Mercury lies deeper in the spacetime bowl that surrounds the Sun than does Earth.

Question 15

According to general relativity,why does Earth orbit the Sun?

Accepted Answer

A) Earth orbits the Sun because the mysterious force that we call gravity holds Earth in orbit. 
B) Earth is following the straightest path possible through spacetime,but this path happens to go around and around the Sun. 
C) Earth orbits the Sun because Earth and Sun are connected by a "rope-like" set of invisible,subatomic particles. 
D) Earth orbits the Sun because a spacetime diagram shows the Sun to be a bowl-shaped dip in a rubber sheet. 
A) Earth orbits the Sun because the mysterious force that we call gravity holds Earth in orbit. 
B) Earth is following the straightest path possible through spacetime,but this path happens to go around and around the Sun. 
C) Earth orbits the Sun because Earth and Sun are connected by a "rope-like" set of invisible,subatomic particles. 
D) Earth orbits the Sun because a spacetime diagram shows the Sun to be a bowl-shaped dip in a rubber sheet.

Question 16

What evidence supports the predicted existence of gravitational waves?

Accepted Answer

A) The orbit of a star system consisting of two neutron stars is slowly decaying,suggesting that energy is being carried away by gravitational waves. 
B) The energy generated by gravitational waves from the Sun can be seen as it is absorbed by Jupiter. 
C) Gravitational waves are frequently and easily detected by large telescopes. 
D) Photographs of spacetime show the gravitational waves as ripples that are clearly visible. 
A) The orbit of a star system consisting of two neutron stars is slowly decaying,suggesting that energy is being carried away by gravitational waves. 
B) The energy generated by gravitational waves from the Sun can be seen as it is absorbed by Jupiter. 
C) Gravitational waves are frequently and easily detected by large telescopes. 
D) Photographs of spacetime show the gravitational waves as ripples that are clearly visible.

Question 17

According to general relativity,what is a black hole?

Accepted Answer

A) an object that cannot be seen 
B) a place where light travels slower than the normal speed of light 
C) a place where the strength of gravity is infinite 
D) a hole in the observable universe 
A) an object that cannot be seen 
B) a place where light travels slower than the normal speed of light 
C) a place where the strength of gravity is infinite 
D) a hole in the observable universe

Question 18

Planes traveling between Seattle and Tokyo often go near Alaska because

Accepted Answer

A) there is less air traffic to contend with. 
B) planes travel faster in cooler air. 
C) the distance is shorter. 
D) the plane can stay over the safety of land for longer. 
A) there is less air traffic to contend with. 
B) planes travel faster in cooler air. 
C) the distance is shorter. 
D) the plane can stay over the safety of land for longer.

Question 19

If you draw a spacetime diagram,the worldline of an object that is traveling by you at constant speed is

Accepted Answer

A) vertical. 
B) horizontal. 
C) slanted. 
D) curved. 
E) a circle. 
A) vertical. 
B) horizontal. 
C) slanted. 
D) curved. 
E) a circle.

Question 20

What does the equivalence principle say?

Accepted Answer

A) Gravity is the same thing as curvature of spacetime. 
B) The effects of gravity are exactly equivalent to the effects of acceleration. 
C) You cannot distinguish between motion at constant velocity and weight in a gravitational field. 
D) The effects of relativity are exactly equivalent to those predicted by Newton's laws of motion. 
E) All observers must always measure the same (equivalent)weights for moving objects. 
A) Gravity is the same thing as curvature of spacetime. 
B) The effects of gravity are exactly equivalent to the effects of acceleration. 
C) You cannot distinguish between motion at constant velocity and weight in a gravitational field. 
D) The effects of relativity are exactly equivalent to those predicted by Newton's laws of motion. 
E) All observers must always measure the same (equivalent)weights for moving objects.

Exam 27: Spacetime and Gravity

What is gravitational lensing? According to general relativity,why does it occur?

Which of the following correctly describes the relationship between Newton's theory of gravity and general relativity?

As predicted by general relativity,time runs slightly slower at the peak of Mount Everest than it does at sea level.

If you draw a spacetime diagram,the worldline of an object that is stationary in your reference frame is

What do we mean by hyperspace?

In your own words,explain what we mean by spacetime.

If your worldline is following the straightest possible path through spacetime,then

Although many scientists believe general relativity to be correct,there is no experimental evidence supporting the predictions this theory makes about time.

What do we mean by the event horizon of a black hole?

Space is different for different observers.Time is different for different observers.Spacetime is the same for everyone.

According to general relativity,how is time affected by gravity?

Suppose you claim that you are feeling the effects of a gravitational field.How can you explain the fact that Al is weightless?

Mercury's perihelion slowly precesses around the Sun by a bit less than 2° per century.This precession can be fully accounted for by Newton's theory of gravity,although general relativity also gives the same answer.

In what way do observations of Mercury support Einstein's general theory of relativity?

According to general relativity,why does Earth orbit the Sun?

What evidence supports the predicted existence of gravitational waves?

According to general relativity,what is a black hole?

Planes traveling between Seattle and Tokyo often go near Alaska because

If you draw a spacetime diagram,the worldline of an object that is traveling by you at constant speed is

What does the equivalence principle say?

A Modern View of the Universe

Discovering the Universe for Yourself

The Science of Astronomy

Making Sense of the Universe: Understanding Motion, Energy, and Gravity

Light and Matter: Reading Messages from the Cosmos

Telescopes: Portals of Discovery

Our Planetary System

Formation of the Solar System

Planetary Geology: Earth and the Other Terrestrial Worlds

Planetary Atmospheres: Earth and the Other Terrestrial Worlds

Jovian Planet Systems

Asteroids, Comets, and Dwarf Planets: Their Nature, Orbits, and Impacts

Other Planetary Systems: The New Science of Distant Worlds

Our Star

Surveying the Stars

Star Birth

Star Stuff

The Bizarre Stellar Graveyard

Our Galaxy

Galaxies and the Foundations of Modern Cosmology

Galaxy Evolution

The Birth of the Universe

Dark Matter, Dark Energy, and the Fate of the Universe

Life in the Universe

Celestial Timekeeping and Navigation

Space and Time

Building Blocks of the Universe

Filters