Module 10 Flashcards
(211 cards)
1
Q
What does the universe consist of?
A
Matter and energy moving through space with the passage of time
2
Q
How are space and time traditionally viewed in everyday life?
A
As absolute and distinct
3
Q
Who discovered that space and time are intertwined?
A
Albert Einstein
4
Q
What is the significance of Einstein’s theory of relativity?
A
It is important for understanding astronomy and the universe
5
Q
When was Albert Einstein born?
A
March 14, 1879
6
Q
What job did Einstein take in 1901?
A
A job with the Swiss patent office
7
Q
What year did Einstein publish the special theory of relativity?
A
1905
8
Q
What is the photoelectric effect?
A
It presented the first concrete evidence of the wave-particle duality of light
9
Q
What phenomenon explains why suspended particles in water jiggle?
A
Brownian motion
10
Q
What does the general theory of relativity include that the special theory does not?
A
The effects of gravity
11
Q
What are thought experiments?
A
Experiments that can be carried out in principle but are difficult in practice
12
Q
What happens to the perception of time for someone moving at a speed close to the speed of light?
A
Time runs more slowly for that person
13
Q
What is a key idea of the special theory of relativity regarding the speed of light?
A
No information can travel faster than the speed of light
14
Q
True or False: According to relativity, all observers agree on the simultaneity of events.
A
False
15
Q
What happens to the length of an object moving at a speed close to the speed of light?
A
Its length is shorter in the direction of motion
16
Q
What happens to the mass of an object moving at a speed close to the speed of light?
A
Its mass is greater than when it is stationary
17
Q
What are the two absolutes in the theory of relativity?
A
- The laws of nature are the same for everyone
- The speed of light is the same for everyone
18
Q
How does relativity view measurements of motion?
A
They make sense only relative to a reference frame
19
Q
What is the speed of light in all reference frames?
A
It is the same for everyone
20
Q
What does the airplane example illustrate about motion?
A
There are multiple valid viewpoints about motion
21
Q
What is a reference frame?
A
A perspective from which motion and measurements are observed
22
Q
What is the relationship between relativity and common sense?
A
Relativity requires a broader perspective that may contradict common sense
23
Q
What paradox might arise when considering Earth’s shape?
A
The idea that Australians should fall off the Earth
24
Q
What is the significance of the speed of light being constant across reference frames?
A
It is a crucial aspect of Einstein’s theory of relativity
25
What helps children revise their understanding of up and down?
Learning that Earth is round
## Footnote
This challenges common sense notions about orientation.
26
Why do most maps show the Northern Hemisphere on top?
It reflects a common convention in cartography
## Footnote
The validity of a map remains unchanged regardless of orientation.
27
What paradoxes did Einstein encounter as a teenager?
Paradoxes related to traveling at or beyond the speed of light
## Footnote
He recognized the need to change common sense ideas about space and time.
28
What are the two absolutes of relativity?
The laws of nature are the same for everyone and everyone measures the same speed of light
## Footnote
These form the basis for thought experiments in relativity.
29
What is a free-float frame?
A reference frame where everything is weightless and floats freely
## Footnote
Also known as inertial reference frames.
30
In Thought Experiment 1, how does Al perceive motion?
Al perceives himself to be at rest
## Footnote
He sees the other person moving away at 90 km/hr.
31
What is true about the perspectives of observers in relative motion?
Both perspectives are equally valid
## Footnote
All motion is relative, leading to the same laws of nature.
32
In Thought Experiment 2, how fast does the ball move relative to Al?
10 km/hr
## Footnote
This is the result of subtracting Al's speed from the ball's speed.
33
In Thought Experiment 3, what happens to the baseball thrown at 90 km/hr?
The ball appears stationary to Al
## Footnote
It matches Al's speed, causing it to seem fixed in his reference frame.
34
What is the significance of the speed of light in relativity?
It is absolute and the same for all observers
## Footnote
This leads to surprising conclusions about relative motion.
35
In Thought Experiment 4, how fast is Al moving relative to you?
At 0.9c
## Footnote
This is 90% of the speed of light.
36
What happens in Thought Experiment 5 when you shine a flashlight while moving at 0.9c?
Al sees the light beam moving at c
## Footnote
This contradicts the expectation of it moving at 0.1c.
37
Why can't any material object reach the speed of light?
Because the speed of light is absolute
## Footnote
No observer can measure an object traveling at or faster than light.
38
What is the conclusion of Thought Experiment 6 regarding headlight beams?
You cannot outrun your headlight beams
## Footnote
This emphasizes the limit of the speed of light.
39
What does relativity say about information transmission?
The speed of light is a limit for transmitting information
## Footnote
No object can transmit information faster than light.
40
What is a common misconception about light moving faster than light?
It seems to move faster in certain scenarios but does not transmit information
## Footnote
Examples include quantum mechanics and laser light between stars.
41
What are the predictions of special relativity based on?
The two basic assumptions of the theory
## Footnote
These involve the uniformity of nature's laws and the constant speed of light.
42
What is the speed of light as measured in any reference frame?
300,000 km/s
## Footnote
This speed is constant and does not change regardless of the observer's motion.
43
What does the special theory of relativity state about measurements of time, length, and mass?
They can be different in different reference frames.
44
What is the name given to the effect where time runs slower for an observer in a moving reference frame?
Time dilation.
45
In the thought experiment with the moving train, how does an outside observer view the ball's path?
The ball's path appears slanted forward.
46
What is the implication of measuring the speed of light in different reference frames?
Both observers will measure the speed of light to be the same.
47
What happens to the perception of time for an observer moving close to the speed of light?
Time runs slower in their reference frame.
48
Fill in the blank: The faster the other reference frame is moving, the more slowly time passes _______.
within it.
49
What is the relativity of simultaneity?
Observers in different reference frames may disagree on the order or simultaneity of events.
50
What happens to the lengths of objects moving relative to you?
They are contracted in their direction of motion.
51
What effect does high speed have on the mass of an object as perceived by a stationary observer?
The mass appears greater than when at rest.
52
True or False: Al and his stationary brother will experience the same acceleration when pushed with the same force.
False.
53
What happens to the speed of an object as it approaches the speed of light?
It requires an infinite amount of force to accelerate an infinite mass.
54
How do you calculate the speed of an object moving towards another moving object?
Using the velocity addition formula.
55
What will Al conclude about Jackie’s speed as she approaches him at 0.8c while he is moving at 0.9c?
Her speed will be less than the speed of light but greater than 0.9c.
56
What fundamental principle underlies the predictions of special relativity?
The speed of light is absolute and the laws of nature are the same for everyone.
57
What is the effect on time for clocks in a moving reference frame compared to a stationary observer?
Clocks in the moving frame run slower.
58
What is the conclusion regarding the observation of simultaneity between different reference frames?
Events that are simultaneous in one frame may not be simultaneous in another.
59
Fill in the blank: The faster an object is moving, the greater the _______ you will find it to have.
mass.
60
What is the speed range of light discussed in the content?
Between 0.9c and c
61
What does the absoluteness of the speed of light state?
The speed of light is always the same, regardless of the observer's motion.
62
Who conducted the Michelson-Morley experiment and what did it demonstrate?
A. A. Michelson and E. W. Morley; it demonstrated that the speed of light is not affected by Earth’s motion around the Sun.
63
What is one way to test the effects predicted by relativity?
By accelerating subatomic particles to speeds near the speed of light in particle accelerators.
64
What happens to the lifetime of a pi meson when produced at speeds close to the speed of light?
It lasts significantly longer than its rest lifetime of 18 nanoseconds due to time dilation.
65
What does the mass increase formula in relativity imply?
The mass of a moving object increases as its speed approaches the speed of light.
66
True or False: Particles can reach the speed of light.
False
67
What did experiments conducted in 2010 at the National Institute of Standards and Technology verify?
The predicted amount of time dilation at speeds of less than 10 meters per second.
68
What is the significance of Einstein's formula E=mc² in relation to relativity?
It explains the energy released in nuclear reactions and is derived from the theory of relativity.
69
How did Olaus Roemer contribute to measuring the speed of light?
He measured the time delay of light from Jupiter's moons to estimate the speed of light.
70
What method did Fizeau and Foucault use to measure the speed of light more precisely?
They used rotating mirrors.
71
Fill in the blank: The speed of light is _______.
absolute
72
What paradox arises if the speed of light is not absolute?
Different observers could witness the same event in different ways.
73
What does the thought experiment involving Al and his spaceship illustrate?
Relativity of time, length, and mass from different frames of reference.
74
What is a key conclusion drawn from the thought experiments about relativity?
The laws of nature are the same for all observers, regardless of their relative motion.
75
What experimental evidence supports the theory of relativity?
Nuclear energy, time dilation in particle accelerators, and the Michelson-Morley experiment.
76
What does the term 'length contraction' refer to?
The phenomenon where an object's length appears shorter when moving at relativistic speeds.
77
What happens to the observed time of an object moving at relativistic speeds?
It appears to run slower compared to an observer's time.
78
What conclusion can be drawn from the fact that we always see distinct stars in binary systems?
It supports the idea that the speed of light is absolute.
79
What happens when Al is moving in slow motion?
You send him a radio message and receive his response in slow motion.
## Footnote
This illustrates the concept of time dilation as perceived by observers moving relative to each other.
80
What is the result of recording Al's slow-motion response and speeding it up?
You hear Al say, 'I’m not moving in slow motion—you are!'
## Footnote
This highlights the relativity of time and how different observers can perceive time differently.
81
What does the argument between you and Al illustrate about time and space?
It shows that time and space are relative, and the disagreement is meaningless based on inadequate definitions.
## Footnote
This reflects the fundamental principles of Einstein's theory of relativity.
82
What is the significance of the speed of light according to relativity?
The speed of light is absolute, while time and space are relative.
## Footnote
This is a core principle of Einstein's special theory of relativity.
83
How does special relativity provide a 'ticket to the stars'?
It allows for time dilation and length contraction, enabling long-distance travel at speeds close to light.
## Footnote
This means that while time passes differently for travelers, they can reach distant stars within their lifetimes.
84
What is the journey time to Vega from the perspective of Earth?
It takes just over 25 years to reach Vega at nearly the speed of light.
## Footnote
This is based on the assumption of traveling at 0.999c.
85
What is the journey time to Vega from the spaceship's perspective?
The trip takes about 1 year due to length contraction.
## Footnote
This illustrates how different reference frames can yield different time measurements.
86
What happens to a person's age during high-speed travel to a distant star?
They age less than people who remain on Earth.
## Footnote
This is a consequence of time dilation.
87
What is the outcome of a round trip to the Andromeda Galaxy from the perspective of Earth?
It would take at least 5 million years.
## Footnote
This demonstrates the vast distances involved in intergalactic travel.
88
What happens if you travel at 50 parts in 1 trillion of the speed of light to the Andromeda Galaxy?
The trip would take only about 50 years from your perspective.
## Footnote
This is an example of how relativity allows for significant differences in time perception.
89
What does relativity offer in terms of returning to the same epoch after a journey?
It only offers a one-way ticket to the stars, not to the same time period.
## Footnote
This means you can return to your starting point but not to the same time.
90
What are the two major ideas that the theory of relativity is based on?
* The laws of nature are the same for everyone
* The speed of light is the same for everyone
91
What is the surprising aspect of the speed of light's absoluteness?
Everyone measures light traveling at the same speed regardless of their own motion.
## Footnote
This contrasts with everyday experiences where velocities are additive.
92
Why can't we reach the speed of light?
Light always travels at the same speed, making it impossible for any observer to measure their own light as moving at the speed of light.
## Footnote
This is a fundamental aspect of relativity.
93
How does relativity change our view of time and space?
Time runs slower, length contracts, and mass increases for objects moving at high speeds.
## Footnote
Observers in different frames may disagree on simultaneity and speeds.
94
How can we make sense of the apparent contradictions in relativity?
Both observers see each other's time running slowly, illustrating the relative nature of time and space.
## Footnote
This is akin to how 'up' and 'down' can differ based on one's perspective on Earth.
95
What is the reality of gravity according to Einstein's general theory of relativity?
Gravity is explained as a consequence of the structure of space and time.
## Footnote
This shifts the understanding of gravitational forces from Newton's law.
96
What is the significance of the explorers running into each other during their journey?
It illustrates that straight paths on a curved surface (Earth) can lead to unexpected outcomes.
## Footnote
This analogy helps understand complex concepts in relativity.
97
98
What happens when two probes are launched in opposite directions from a space station?
They will meet as they orbit Earth.
99
What does the general theory of relativity say about curved paths?
Curved paths are caused by the force of gravity and distortions of spacetime.
100
What is spacetime?
A four-dimensional combination of the three dimensions of space and one dimension of time.
101
How does matter affect spacetime according to general relativity?
Matter shapes the fabric of spacetime, analogous to how heavy weights distort a rubber sheet.
102
What are the major ideas of general relativity? List them.
* Gravity arises from distortions of spacetime.
* Time runs slowly in gravitational fields.
* Black holes can exist in spacetime.
* The universe can have a finite volume without having a center or boundaries.
* Large masses emit gravitational waves.
103
What is the fundamental assumption of general relativity?
The laws of nature are the same for everyone, and all motion is relative, including acceleration.
104
What is the equivalence principle?
The effects of gravity are exactly equivalent to the effects of acceleration.
105
How does the equivalence principle explain the sensation of weight?
Weight can be attributed to effects of either acceleration or gravity.
106
What happens to an astronaut accelerating at 1g in space?
They feel a force pressing them against the floor of their spaceship.
107
What is the significance of the equivalence principle in general relativity?
It allows us to treat all motion as relative and leads to fundamental changes in understanding gravity.
108
How is spacetime different from three-dimensional space?
Spacetime includes a fourth dimension: time.
109
What is the interval in spacetime?
A quantity that different observers agree upon, despite differing values of x, y, z, and t.
110
True or False: The interval between two events can be zero even if they occur at different locations in spacetime.
True.
111
What does the minus sign in the interval formula indicate?
It makes the geometry of spacetime complex.
112
What historical leap did Einstein make regarding the equivalence principle?
He proposed that the effects of gravity and acceleration are the same, challenging prior assumptions.
113
Fill in the blank: Spacetime is a _______ space.
four-dimensional
114
What does the rubber sheet analogy illustrate?
Matter distorts the fabric of spacetime.
115
What is spacetime?
Spacetime is a four-dimensional space consisting of length, width, depth, and time.
116
How does time differ from the other dimensions in spacetime?
Time differs in an important way from the other three dimensions.
117
What happens to objects in spacetime?
Objects are stretched out through time, appearing as four-dimensional objects.
118
What is a worldline in spacetime?
A worldline is the path of an object through four-dimensional spacetime.
119
What does a vertical worldline represent?
A vertical worldline represents an object at rest.
120
What does a slanted worldline indicate?
A slanted worldline indicates an object moving at constant velocity.
121
What does a curved worldline represent?
A curved worldline represents an accelerating object.
122
What is the significance of the angle between two worldlines?
The angle indicates different perspectives on the same four-dimensional reality.
123
What is curved spacetime?
Curved spacetime refers to the bending of spacetime, affecting the paths of objects.
124
What are the three basic types of geometry?
* Flat geometry (Euclidean) * Spherical geometry * Saddle-shaped geometry (hyperbolic)
125
What defines a great circle on Earth's surface?
A great circle is the shortest distance between two points, centered at the center of Earth.
126
What is the geometry of the universe?
The universe's geometry is a mixture of flat, spherical, and saddle-shaped geometries.
127
What does it mean if spacetime is flat?
If spacetime is flat, the rules of geometry for a flat plane hold.
128
What does the equivalence principle state?
The equivalence principle states that weight can be attributed to acceleration or a gravitational field.
129
Fill in the blank: The path of an object following the straightest possible path in spacetime indicates _______.
the shape of spacetime
130
True or False: Different observers measure time and space the same way.
False
131
What visual analogy is used to explain the curvature of spacetime?
The curvature of a two-dimensional surface, like a bent sheet of paper or Earth's surface.
132
What is a spacetime diagram?
A graph that represents one dimension of space and the dimension of time on a single graph.
133
What is the significance of light beams in spacetime diagrams?
Light beams make 45° lines in spacetime diagrams because light travels 1 light-second of distance with each second of time.
134
How do observers perceive time and space differently?
Observers in different reference frames can measure time and space differently.
135
What happens to parallel lines on a spherical surface?
Parallel lines eventually converge.
136
What is the sum of angles in a triangle on a spherical surface?
Greater than 180°.
137
How does the curvature of spacetime affect the paths of objects?
Curved spacetime causes objects to follow curved paths instead of straight ones.
138
Fill in the blank: If the circumference of a circle in space is less than ______, the space has spherical geometry.
2πr
139
What is the implication of a finite spherical geometry for spacetime?
Spacetime is finite but has no center or edges.
140
What does the equivalence principle state?
We can attribute a feeling of weight to either a force generated by acceleration or a gravitational field.
141
What happens to objects experiencing weightlessness according to the equivalence principle?
They are traveling in a straight line, the straightest possible path through spacetime.
142
What is the significance of orbits in the context of spacetime geometry?
Orbits represent paths following the straightest possible path through spacetime.
143
How does Newton's law of gravity explain gravitational attraction?
Every mass exerts a gravitational attraction on every other mass regardless of distance.
144
What was Newton's perspective on 'action at a distance'?
He found it absurd and believed no competent thinker could accept it.
145
How does Einstein's general theory of relativity explain gravity?
Gravity arises from the curvature of spacetime, not from a force acting at a distance.
146
What does the rubber sheet analogy help illustrate?
The curvature of spacetime and how it affects the motion of masses.
147
What happens to the paths of objects in curved spacetime?
They follow the straightest possible paths determined by the curvature.
148
What is a black hole?
A region of spacetime so curved that nothing can escape from it once crossed the event horizon.
149
What is the event horizon in the context of a black hole?
The boundary marking the point of no return for objects falling into a black hole.
150
How does gravity affect time according to general relativity?
Gravity causes time to run more slowly at lower altitudes in a gravitational field.
151
What is gravitational time dilation?
The effect where time passes more slowly in stronger gravitational fields.
152
What is the relationship between mass, density, and gravitational strength?
Greater mass or increased density leads to stronger gravitational attraction.
153
Fill in the blank: According to general relativity, gravity arises from the __________ of spacetime.
curvature
154
True or False: According to general relativity, planets orbit the Sun due to a mysterious force exerted by the Sun.
False
155
What are the orbital shapes that objects in spacetime can follow?
* Circular
* Elliptical
* Unbound parabolic
* Hyperbolic
156
What is the significance of the curvature of spacetime near the Sun?
It dictates the paths of freely moving masses like the planets.
157
How does the rubber sheet analogy simplify the understanding of orbits?
By showing how mass curves spacetime and affects the paths of objects.
158
What does the term 'free-fall' refer to in the context of orbits?
A trajectory where an object is only influenced by gravity.
159
What change occurs to the perception of time during acceleration in a spaceship?
Time appears to run slower at the back of the spaceship compared to the front.
160
What happens to the curvature of spacetime as mass is compressed into a smaller volume?
The curvature increases, leading to stronger gravitational effects.
161
What is the effect of firing a spaceship's engines on the astronauts' experience of weight?
They will feel weight during acceleration or deceleration.
162
Fill in the blank: The curvature of spacetime increases as __________ increases.
mass
163
What does the analogy of rolling marbles on a rubber sheet demonstrate?
How objects follow curved paths in a gravitational field.
164
How does time behave in a uniform gravitational field?
Time runs more slowly at lower altitudes than at higher altitudes.
165
What is the relationship between the strength of gravity and the curvature of spacetime?
Stronger gravity corresponds to greater curvature of spacetime.
166
What is the implication of the rubber sheet analogy for understanding planetary motion?
Planets move in curved paths due to the curvature of spacetime around massive bodies.
167
What is gravitational time dilation?
Time runs more slowly at lower altitudes than at higher altitudes in a gravitational field.
## Footnote
The effect is more pronounced in stronger gravitational fields.
168
How does gravity affect the passage of time according to general relativity?
The stronger the gravity, the greater the curvature of spacetime, leading to greater gravitational time dilation.
169
Which object has the most noticeable gravitational time dilation effect?
A black hole.
170
What is the significance of Mercury’s orbit in testing general relativity?
Einstein explained the precession of Mercury's orbit, which Newton's laws could not fully account for.
171
What key principle did Einstein use to explain Mercury's orbit?
The equivalence principle.
172
What phenomenon occurs when light rays pass near a massive object?
Gravitational lensing.
173
What does gravitational lensing cause?
It can create distorted or multiple images of a distant object.
174
What is microlensing?
A temporary increase in brightness of a distant star caused by a small, dim object passing in front of it.
175
What is gravitational redshift?
The phenomenon where light emitted from a gravitational field appears redshifted due to time running more slowly in stronger gravitational fields.
176
What are gravitational waves?
Ripples in the curvature of space caused by major changes in mass distribution, predicted by general relativity.
177
What is the Laser Interferometer Gravitational-Wave Observatory (LIGO)?
A facility designed to detect gravitational waves by measuring changes in distances using laser beams.
178
When did LIGO first detect gravitational waves?
In 2015.
179
What can gravitational waves indicate about binary neutron stars?
They can reveal orbital decay due to energy loss from gravitational waves.
180
What is a wormhole?
A hypothetical tunnel through spacetime that could create shortcuts between distant points in the universe.
181
True or False: Time runs faster at higher altitudes than at lower altitudes.
False.
182
Fill in the blank: The discrepancy in Mercury's orbit was explained by the _______ of spacetime.
curvature
183
What is the relationship between gravitational time dilation and GPS accuracy?
GPS accounts for gravitational time dilation to maintain accuracy.
184
What is the effect of gravitational fields on atomic clocks?
Clocks in stronger gravitational fields tick more slowly.
185
What happens to light from a star when it passes near a massive object?
Its path curves due to the curvature of spacetime.
186
What did Einstein initially doubt about gravitational waves?
He doubted they would ever be detectable.
187
What is the primary method LIGO uses to detect gravitational waves?
Interference patterns from laser beams measuring changes in arm lengths.
188
How do gravitational waves propagate through space?
Like ripples on a pond.
189
What was a significant result from the first detection of gravitational waves?
It came from the merger of two black holes.
190
What is the distance from Earth to the star Vega?
25 light-years
191
What is a wormhole?
A tunnel through hyperspace that creates a shortcut between two points in space
192
What phenomenon allows a spaceship to travel from Earth to Vega in a few minutes?
Taking a shortcut through a wormhole
193
True or False: A spaceship traveling through a wormhole exceeds the speed of light.
False
194
What is the Twin Paradox?
A thought experiment where one twin ages less than the other due to traveling at high speed
195
What happens to time for the twin that accelerates during the Twin Paradox?
Less time passes for the traveling twin
196
Fill in the blank: The maximum amount of time recorded between two events in spacetime occurs if you follow the _______.
straightest possible path
197
What is the equivalence principle?
The principle stating that the effects of gravity are equivalent to the effects of acceleration
198
What does general relativity state about gravity?
Gravity arises from the curvature of spacetime
199
How does mass affect spacetime?
Mass causes spacetime to curve
200
What is a black hole?
A region of spacetime so curved that it forms a bottomless pit
201
What is gravitational time dilation?
The effect where time runs more slowly in stronger gravitational fields
202
What observation confirms the predictions of general relativity regarding Mercury's orbit?
The precession of Mercury’s orbit
203
What are gravitational waves?
Waves produced by accelerating masses that travel at the speed of light
204
What instrument has detected gravitational waves?
LIGO
205
What is the significance of hyperspace in the context of relativity?
Hyperspace may allow shortcuts that could enable rapid travel without violating relativity
206
True or False: Current physics rules out the possibility of time travel.
False
207
What philosophical implications does relativity raise?
Debates about fate and free will
208
What did Hermann Minkowski say about space and time?
Space and time are intertwined and cannot exist independently
209
How has relativity changed our view of space and time?
Space and time are now understood to be part of a single entity called spacetime
210
Fill in the blank: Gravity is not a mysterious force but a result of the _______.
curvature of spacetime
211
What is the relationship between the geometry of spacetime and gravitational effects?
Curvature of spacetime determines the paths of freely moving masses
