Particles, forces and the big bang Flashcards
(180 cards)
1
Q
What is Cosmology
A
The science of the origin and development of the universe
2
Q
What is the Cosmological Principle?
A
Viewed on a sufficiently large scale, the properties of the universe are the same for all observers
All observers in universe would thus agree on large scale structure and properties of the universe
3
Q
What are the three assumptions of the Cosmological Principle
A
Universality, Homogeneity and Iostropy
4
Q
What is Universality?
A
The law of physics are the same everywhere, even if conditions vary from place to place or time to time
4
Q
What is Homogeneity?
A
Matter is evenly distributed throughout the universe
5
Q
What is Isotropy?
A
No direction is special. The universe looks the same in all directions
6
Q
A
7
Q
A
8
Q
Who is the lecturer for the course ‘Particles, Forces and the Big Bang’?
A
Dr. Martin Habedank
9
Q
What is the main research focus of Dr. Martin Habedank?
A
ATLAS Experiment at the CERN Large Hadron Collider and search for Dark Matter
10
Q
What is a light-year?
A
The distance travelled by light in one year, approximately 9.4607 × 10^15 m
11
Q
What is the approximate number of stars in the observable universe?
A
∼ 10^23
12
Q
What is the estimated number of grains of sand on all beaches on Earth?
A
∼ 10^19
13
Q
What are the two main components of the universe discussed in the course?
A
Dark Matter and Dark Energy
14
Q
What does the Cosmological Principle state?
A
The universe is homogeneous and isotropic
15
Q
Fill in the blank: An order of magnitude is a power of _______.
A
10
16
Q
How many orders of magnitude larger is Earth’s diameter compared to a human’s?
A
About 7 magnitudes
17
Q
What is the fate of the universe?
A
A key question in cosmology
18
Q
What is the size of the observable universe?
A
≳ 93 billion light years
19
Q
How many stars are visible to the naked eye from Earth?
A
∼ 2000
20
Q
What is the approximate distance of 1 light-day in meters?
A
2.6 × 10^13 m
21
Q
What are the two categories of questions addressed in cosmology?
A
Big and small questions
22
Q
What is the structure of the universe?
A
A fundamental question in cosmology
23
Q
True or False: The universe is static.
A
False
24
What are the smallest particles that matter is made of?
A key question in particle physics
25
What is the scale of the universe described in?
Powers of 10
26
What is the course Moodle page URL?
https://moodle.gla.ac.uk/course/view.php?id=45112
27
What is the significance of the ATLAS Experiment?
Search for new particles and phenomena at the LHC
28
What are the supplementary chapters recommended for reading?
Chapters 13-14 and 22-23 from 'The Cosmic Perspective'
29
What are the main topics covered in the course?
* The universe and cosmology
* Evidence for the Big Bang
* Particle physics and the Standard Model
* The evolution of the universe
* Outstanding cosmological problems
30
What is cosmology?
The science of the origin and development of the universe.
## Footnote
Distinct from astronomy/astrophysics, but uses results from them.
31
What does the Cosmological Principle state?
The properties of the universe are the same for all observers on a sufficiently large scale.
32
What are the three important assumptions implicit in the Cosmological Principle?
* Universality
* Homogeneity
* Isotropy
33
Define universality in the context of cosmology.
The laws of physics are the same everywhere, even if conditions vary from place to place or time to time.
34
Define homogeneity in the context of cosmology.
Matter is evenly distributed throughout the universe.
35
Define isotropy in the context of cosmology.
No direction is special; the universe looks the same in all directions.
36
True or False: Homogeneity is true in an absolute sense.
False.
37
What does it mean that the universe evolves?
The universe looks different at different times.
38
What is the focus of cosmology?
The discussion of very large distance scales.
39
What is the focus of particle physics?
The discussion of very small distance scales.
40
How many orders of magnitude must the physics required to describe the universe encompass?
About 60 orders of magnitude.
41
What is the fate of the universe?
An open question in cosmology.
42
Is the universe static?
An open question in cosmology.
43
What are the smallest particles that make up matter?
An open question in particle physics.
44
Can we understand how the smallest particles affect the world as we see it?
An open question in particle physics.
45
Fill in the blank: The discussion of very large distance scales is called _______.
[Cosmology]
46
Fill in the blank: The discussion of very small distance scales is called _______.
[Particle Physics]
47
How are the very big and the very small connected?
An open question in cosmology and particle physics.
48
What is the importance of the Cosmological Principle?
It leads to principles of Universality, Homogeneity, and Isotropy.
49
What is the study of very large distance scales called?
Cosmology
50
What is the study of very small distance scales called?
Particle Physics
51
What is the Cosmological Principle?
An assumption that the properties of the universe are the same for all observers
52
List the principles that arise from the Cosmological Principle.
* Universality
* Homogeneity
* Isotropy
53
Approximately how many years ago did the Big Bang occur?
13.7 billion years ago
54
What was the state of the universe at the time of the Big Bang?
Very hot and dense
55
What major event is described by the Big Bang model?
Rapid expansion and cooling of the universe
56
What is Olbers' Paradox?
The question of why the night sky is dark if the universe is infinite and filled with stars
57
What would happen if the universe were static and filled with stars according to the hypothesis of Olbers' Paradox?
The sky would be as bright as the surface of a star
58
What is one proposed solution to Olbers' Paradox?
Dust obscures the starlight
59
Why is the dust obscuring starlight solution to Olbers' Paradox considered wrong?
The dust would heat up and eventually glow as brightly as a star
60
What did Kepler believe regarding the number of stars in the universe?
That the universe has a finite number of stars
61
What is one characteristic of the observable universe regarding stars?
It has a finite number of stars
62
According to Carl Charlier, what arrangement of stars could potentially solve Olbers' Paradox?
A fractal pattern
63
What does the Cosmic Microwave Background signify?
Evidence of the Big Bang
64
What does the Hubble-Lemaître Law describe?
The relation between the distance of galaxies and their redshift
65
Fill in the blank: The universe is _______.
expanding
66
List the evidence for the Big Bang.
* It is dark at night
* The universe is expanding
* We observe a cosmic microwave background
* It predicts correct relic abundances of elements
67
True or False: The Big Bang model suggests that matter was captured by gravity leading to structure formation.
True
68
What did Edgar Allan Poe suggest regarding the background of the sky?
That it would present a uniform luminosity if stars were endless
69
What significant cosmological problem does Olbers' Paradox highlight?
The contradiction of a dark night sky versus an infinite universe filled with stars
70
What does the voids found by telescopes imply about the universe?
The universe is not eternal but has a finite age rather than finite size.
71
Who conducted the first quantitative analysis of the problem regarding the universe's age?
Lord Kelvin.
72
What is Olbers’ Paradox?
It questions why the night sky is dark if the universe is infinite and eternal.
73
What does the finite age of the universe suggest about the light from distant stars?
Light from very far away stars has not yet reached us.
74
How old is the universe estimated to be?
Approximately 13.7 billion years.
75
What is the current estimated size of the observable universe?
About 93 billion light years across.
76
What significant discovery did Edwin Hubble make in 1928?
He measured the distance of close galaxies.
77
What method is used to judge the distance to objects in space?
The 'distance ladder' using measured and expected brightness.
78
What effect does a wave emitted from a moving source experience?
The apparent wavelength is altered by the direction of the source.
79
What happens to the wavelength of light if the source is moving away from the observer?
The wavelength will be longer (redshift).
80
What phenomenon do astronomers observe when looking at distant objects?
Distant objects emit light that appears more red than expected.
81
What does the term 'redshift' indicate?
That distant sources are moving away from us.
82
What does Hubble's Law state?
The speed a galaxy moves away from us is proportional to its distance from us.
83
What is the formula for Hubble's Law?
v = H₀ × d.
84
What is Hubble's constant approximately equal to?
69.32 ± 0.80 km/s/Mpc.
85
What does the expansion of the universe imply about galaxies?
Galaxies are moving away from every point in the universe.
86
What is the nature of the expansion of the universe?
Expansion of space itself, not into anything.
87
Who first predicted the Cosmic Microwave Background Radiation (CMBR)?
Alpher and Herman in 1948.
88
What did Penzias and Wilson discover in 1964?
They detected isotropic background radiation indicating a cosmic source.
89
What does the 'surface of last scattering' refer to?
The moment when the universe became transparent after forming neutral atoms.
90
What is the temperature of the Cosmic Microwave Background Radiation?
2.72548 ± 0.00057 K.
91
What did Planck's solution to the ultraviolet catastrophe involve?
Energy is quantised.
92
What is the significance of the CMBR being a near-perfect black-body spectrum?
It indicates the characteristics of the early universe.
93
What is the effect of the expansion of the universe on the CMBR?
It has been redshifted from an original temperature of approximately 3000 K.
94
What do measurements of the CMBR reveal?
A map of the universe 379,000 years after the Big Bang.
95
What does CMBR stand for?
Cosmic Microwave Background Radiation
## Footnote
CMBR is a remnant from the early universe.
96
What is the significance of the CMBR measurements?
They reveal a map of the universe 379,000 years after the Big Bang
## Footnote
Increasing angular resolution in measurements shows more structure.
97
What does Olbers' paradox suggest about a static eternal universe?
The night sky should be as bright as the surface of the sun
## Footnote
This paradox is resolved by the Big Bang theory.
98
How does the Big Bang resolve Olbers' paradox?
There was a time when there were no stars
## Footnote
Distant stars' light has not had time to reach us.
99
What is the Hubble-Lemaître Law?
It states that other galaxies are moving away from us at speeds proportional to their distance
## Footnote
This law implies an expanding universe.
100
What is Hubble's constant?
The constant of proportionality in the Hubble-Lemaître Law
## Footnote
It quantifies the rate of expansion of the universe.
101
How do we measure the speed of distant objects in the universe?
Using redshift
## Footnote
Redshift occurs because light from objects moving away has a longer wavelength.
102
What is the Cosmic Microwave Background observed by Penzias and Wilson?
A microwave hiss from all over the sky
## Footnote
It represents the first free traveling photons after the Big Bang.
103
What does the Cosmic Microwave Background signify?
It is emitted from the surface of last scattering and is redshifted by the expansion of the universe
## Footnote
This redshift indicates that the universe is expanding.
104
Fill in the blank: The light from very distant stars has not had time to _______.
reach us
105
Which statement about evidence in support of the Big Bang model is FALSE?
The observation of gravitational waves is evidence for the Big Bang model.
106
What does Olber’s paradox state regarding the night sky?
The night sky should be bright if the Universe were infinitely old.
107
What is the significance of the cosmic microwave background (CMB) in relation to the Big Bang model?
The CMB shows that the universe was once very uniform and in thermal equilibrium.
108
What do the relic abundances of light elements in the universe indicate?
They match predictions for how elements would be produced following the Big Bang.
109
Which assumption leading to Olber’s paradox is WRONG?
The Universe is eternal.
110
What does the assumption that the Universe is infinite in size imply?
Cosmological observations are consistent with an infinite Universe.
111
What is required for the assumption that the Universe is uniformly filled with stars to be true?
Stars would need to be arranged in very specific ways.
112
How does the amount of light from a star change with distance?
It decreases as 1/r².
113
What are the key topics covered in the course content?
* The universe and cosmology
* Evidence for the Big Bang
* The history of cosmology
* Particle physics and the Standard Model
* The evolution of the universe
* Dark Matter and Dark Energy
* The fate of the universe
* Some outstanding cosmological problems
114
What is the difference between mythic cosmology and physical cosmology?
Mythic cosmology is based on supernatural events, while physical cosmology is based on observation and prediction.
115
Who is credited with the first scientific 'cosmology'?
Thales of Mileteus.
116
What did Eudoxus create to explain retrograde motion?
A system of 26 concentric spheres.
117
What observation did retrograde motion present to early astronomers?
Planets appear to sometimes reverse direction.
118
What did Aristotle assert about heavenly bodies?
They were made from a 'perfect and unchanging celestial material.'
119
Who believed that the Earth rotated on its axis?
Heracleides of Athens.
120
What did Aristarchus of Samos propose about the Earth?
That the Earth goes around the Sun.
121
What method did Eratosthenes use to measure the Earth's circumference?
He measured the shadow of a column in Alexandria at noon.
122
What was the estimated circumference of the Earth calculated by Eratosthenes?
Approximately 42,000 km.
123
What is the basis of Ptolemy's geocentric cosmology?
All heavenly motion was based on circles with planetary orbits centered on the Earth.
124
What was a major feature of Copernican theory?
The Sun is at the center of the universe.
125
What did Copernicus claim about the distances from the Earth to the Sun?
They are small compared to the distance to the stars.
126
What three motions does the Earth have according to Copernicus?
* Daily rotation
* Annual revolution
* Annual tilting of its axis
127
Who was Tycho Brahe?
A Danish observational astronomer.
128
What did Tycho Brahe observe in 1572?
A supernova.
129
What was Galileo Galilei known for?
Being an Italian astronomer and scientist.
130
What device did Galileo utilize for his astronomical observations?
A telescope.
131
Who was Galileo Galilei?
An Italian astronomer and scientist (1564–1642)
132
When did telescopes first appear?
In the Netherlands in 1608
133
What significant observation did Galileo make about Jupiter?
Jupiter has moons
134
What conclusion did Galileo draw from the moons of Jupiter?
Earth is not the centre of the universe
135
What did Galileo observe about the moon?
The moon has mountains and craters
136
What conclusion did Galileo draw from the imperfections of celestial bodies?
Celestial bodies are not perfect
137
What is the composition of the Milky Way according to Galileo?
The Milky Way is made of stars
138
What conclusion did Galileo draw about stars?
Stars are very far away and probably not made for humans
139
What observation did Galileo make about Venus?
Venus has phases similar but not identical to the moon
140
What conclusion did Galileo draw from the phases of Venus?
At least Venus certainly doesn’t orbit Earth
141
What happened to Galileo at age 70?
He was tried for heresy for contradicting the church's official position
142
Who was Johannes Kepler?
A mathematician and astronomer (1571-1630) who worked with Tycho Brahe
143
What did Kepler discover using Brahe’s instruments?
The first accurate mathematical laws that the planets obey
144
What is Kepler's first law?
The planets follow elliptical orbits, with the Sun at one of the foci
145
What is Kepler's second law?
A line joining a planet and the Sun sweeps out equal areas during equal intervals of time
146
What is Kepler's third law?
(Period)^2 ∝ (Average radius)^3
147
Who was Isaac Newton?
A scientist (1642–1727) who made contributions to various fields including astronomy
148
What was Newton's main contribution to astronomy?
His realization that the law of gravity governs planetary motion
149
What does Newton's inverse square law of gravitation state?
F ∝ m1m2 / r^2
150
Who is Albert Einstein?
A physicist (1879–1955) known for his Special and General Theories of Relativity
151
What is the first postulate of Einstein's special theory of relativity?
The laws of physics are the same in all inertial frames of reference
152
What is the second postulate of Einstein's special theory of relativity?
The speed of light in vacuum is the same in all inertial frames of reference
153
What is a consequence of the special theory of relativity?
Nothing can go faster than light
154
What does the special theory of relativity imply about moving clocks?
Moving clocks tick more slowly
155
What does the special theory of relativity imply about moving objects?
Moving objects are shrunk in the direction of motion
156
What concept links space and time in relativity?
4D space-time
157
What does Einstein's general theory of relativity state about gravity?
Gravity is an effect caused by the curvature of space-time
158
What tells space-time how to curve in general relativity?
Energy
159
What tells matter how to move in general relativity?
The curvature of space-time
160
What are some consequences of general relativity?
* Time runs slower in strong gravitational fields
* Gravitational lensing
* Binary pulsars
* Black holes
* Gravitational waves
161
What discovery by LIGO was made in 2015/16?
Gravitational waves
162
What significant realization did Harlow Shapley make in 1916?
The Milky Way is much bigger than previously thought
163
What did Edwin Hubble demonstrate in 1929?
The universe is expanding (Hubble-Lemaître law)
164
What did Fritz Zwicky infer in 1933?
The bulk of matter in the Coma galaxy cluster is dark
165
What model did George Gamow develop in 1948?
A model of Big Bang nucleosynthesis
166
What did Arno Penzias and Robert Wilson discover in 1964?
The Cosmic Microwave Background
167
What is physical cosmology?
The use of observations and predictions to present a scientific view of the origin and development of the universe
168
What did Greek philosophers believe about the Earth's position in the universe?
They believed that Earth was at the centre of the universe
169
Who first presented the modern heliocentric model of the universe?
Copernicus, supported by Galileo and Kepler
170
What did Newton formulate to explain Kepler’s observations?
The first theory of gravity
171
What is Physical Cosmology?
The use of observations and predictions to present a scientific view of the origin and development of the universe.
## Footnote
This field combines aspects of astronomy and physics to understand cosmic phenomena.
172
Who were the first to use science to describe cosmology?
Greek philosophers.
## Footnote
They believed that Earth was at the centre of the universe.
173
Who presented the first modern heliocentric model of the universe?
Copernicus.
## Footnote
His model was supported by Galileo and Kepler.
174
What did Kepler show about the orbits of planets?
Planets follow elliptical orbits.
## Footnote
This is known as Kepler's Laws.
175
Who formulated the first theory of gravity?
Newton.
## Footnote
He explained Kepler’s observations with his gravitational theory.
176
What did Einstein revolutionize with his theories?
Physics.
## Footnote
His theories include Special and General Relativity.
177
What does General Relativity present about gravity?
Gravity is caused by space-time curvature.
## Footnote
This was a significant shift from Newtonian physics.
178
What did Shapley and Hubble demonstrate about the universe?
The universe isn’t just our own galaxy and it is expanding.
## Footnote
Their work contributed to the understanding of the universe's vastness.
179
What model builds on the work of scientists like Lemaître and Gamow?
The Big Bang model.
## Footnote
This model explains the origin of the universe and its expansion.
