Question 1

The cosmological principle states that any observer in any galaxy will see the same general features of the universe.

Accepted Answer

A) True 
 B)False

Question 2

Why is the cosmic microwave background (CMB) so cold,if the early universe was so hot?

Accepted Answer

A)  Enough time has passed for matter in the universe to release enough heat to cool down.
B)  The CMB constantly interacts with atoms, which effectively cools down the photons.
C)  The expansion of the universe has redshifted those photons to an effectively cooler temperature.
D)  The Big Bang was initially hot but the CMB was released from cold material much later on.E) A) and B)
F) A) and C)

Question 3

How do we know there was a Big Bang?

Accepted Answer

The Big Bang theory is the prevailing co...

Question 4

What property of an antiproton is opposite to that of a proton?

Accepted Answer

A)  mass
B)  velocity
C)  electric charge
D)  direction of spinE) A) and B)
F) C) and D)

Question 5

What properties does the cosmological principle require the universe to have?

Accepted Answer

A)  homogeneous and expanding
B)  homogeneous and isotropic
C)  isotropic and accelerating
D)  isotropic and expandingE) All of the above
F) B) and D)

Question 6

What do current observations indicate about the amount of baryonic matter and dark matter in the universe?

Accepted Answer

A)  The total amount detected is sufficient to overcome the expansion of the universe.
B)  The total amount detected implies that the universe is closed.
C)  The amounts of the two kinds of matter are roughly equal.
D)  The total amount detected implies that the universe is open.E) A) and B)
F) B) and C)

Question 7

What happens when a proton and an antiproton collide?

Accepted Answer

A)  They destroy each other and produce energy in the form of gamma rays.
B)  One of the protons is converted to a neutron and they form a nucleus of one proton and one neutron.
C)  One of the protons is converted to an electron and they form a hydrogen atom.
D)  One proton is converted to a neutron and the other is converted to an electron.E) A) and B)
F) C) and D)

Question 8

Why is the primordial background radiation visible in all directions?

Accepted Answer

The answer of Why is the primordial background radiation visible...

Question 9

Under what conditions will space-time be flat?

Accepted Answer

A)  if the universe is expanding
B)  if the universe is finite
C)  if the average density of the universe is equal to the critical density
D)  if the universe is homogeneous and isotropicE) None of the above
F) All of the above

Question 10

Why would a value of 100 km/sec/Mpc for the Hubble constant contradict theories of stellar evolution?

Accepted Answer

A value of 100 km/sec/Mpc for the Hubble...

Question 11

The ____________________ is that the universe is both isotropic and homogeneous.

Accepted Answer

cosmologic...

Question 12

Where did the cosmic microwave background (CMB) come from?

Accepted Answer

A)  photons emitted from the first stars
B)  photons released from hydrogen in our galaxy
C)  light scattered by dust in our solar system
D)  photons released when electrons and nuclei combined for the first timeE) A) and C)
F) A) and D)

Question 13

The cosmic background radiation comes from a particular time after the origin of the universe.What was that time?

Accepted Answer

A)  when protons and neutrons were first formed
B)  when the Big Bang first began to expand
C)  when gamma rays had enough energy to destroy nuclei
D)  when electrons began to recombine with nuclei to form atomsE) A) and B)
F) A) and C) D

Question 14

What characteristic of the universe governs whether the universe is open,closed,or flat?

Accepted Answer

A)  density
B)  temperature
C)  radius
D)  rotation rateE) B) and C)
F) C) and D) A

Question 15

How does the geometry of a gravity-dominated universe relate to its density?

Accepted Answer

A)  If the universe is closed, the density is equal to the critical density.
B)  If the universe is flat, the density is equal to the critical density
C)  If the universe is open, the density is equal to the critical density.
D)  if the universe is open, the density is greater than the critical density.E) B) and C)
F) All of the above

Question 16

As the universe cooled,it eventually reached a temperature of 3,000 K and protons were able to capture and hold electrons to form neutral hydrogen.What is this process called?

Accepted Answer

A)  ionization
B)  isotropy
C)  annihilation
D)  recombinationE) A) and B)
F) A) and C)

Question 17

What does the resolution of Olbers' paradox say about why it gets dark at night?

Accepted Answer

A)  It gets dark at night because the universe is not infinite in age.
B)  It gets dark at night because the universe is static.
C)  It gets dark at night because the universe is closed.
D)  It gets dark at night because the universe contains dust.E) A) and B)
F) A) and C)

Question 18

Which of the following best describes the horizon problem?

Accepted Answer

A)  the nearness of the universe to critical density
B)  the isotropy of the cosmic microwave background
C)  the existence of the inflationary Big Bang
D)  the limited size of the observable universeE) B) and D)
F) B) and C) B

Question 19

What could be the origin of the galaxy seeds around which galaxies,clusters,and walls grew?

Accepted Answer

A)  hot dark matter
B)  baryons
C)  the separation of the electromagnetic and weak forces
D)  quantum fluctuations in space-timeE) A) and B)
F) A) and C)

Question 20

Which of the following applies if the universe is closed?

Accepted Answer

A)  The universe will expand forever.
B)  The universe has a centre.
C)  The universe has an edge.
D)  The universe has a high density.E) B) and D)
F) B) and C)

Exam 11: Cosmology in the 21st Century

The cosmological principle states that any observer in any galaxy will see the same general features of the universe.

Correct AnswerverifiedShow Answer

Why is the cosmic microwave background (CMB) so cold,if the early universe was so hot?

Correct AnswerverifiedShow Answer

How do we know there was a Big Bang?

Correct AnswerAnswered by ExamLex AIThe Big Bang theory is the prevailing co...View AnswerShow Answer

What property of an antiproton is opposite to that of a proton?

Correct AnswerverifiedShow Answer

What properties does the cosmological principle require the universe to have?

Correct AnswerverifiedShow Answer

What do current observations indicate about the amount of baryonic matter and dark matter in the universe?

Correct AnswerverifiedShow Answer

What happens when a proton and an antiproton collide?

Correct AnswerverifiedShow Answer

Why is the primordial background radiation visible in all directions?

Correct AnswerverifiedShow Answer

Under what conditions will space-time be flat?

Correct AnswerverifiedShow Answer

Why would a value of 100 km/sec/Mpc for the Hubble constant contradict theories of stellar evolution?

Correct AnswerAnswered by ExamLex AIA value of 100 km/sec/Mpc for the Hubble...View AnswerShow Answer

The ____________________ is that the universe is both isotropic and homogeneous.

Correct Answerverifiedcosmologic...View AnswerShow Answer

Where did the cosmic microwave background (CMB) come from?

Correct AnswerverifiedShow Answer

The cosmic background radiation comes from a particular time after the origin of the universe.What was that time?

Correct AnswerverifiedD

What characteristic of the universe governs whether the universe is open,closed,or flat?

Correct AnswerverifiedA

How does the geometry of a gravity-dominated universe relate to its density?

Correct AnswerverifiedShow Answer

As the universe cooled,it eventually reached a temperature of 3,000 K and protons were able to capture and hold electrons to form neutral hydrogen.What is this process called?

Correct AnswerverifiedShow Answer

What does the resolution of Olbers' paradox say about why it gets dark at night?

Correct AnswerverifiedShow Answer

Which of the following best describes the horizon problem?

Correct AnswerverifiedB

What could be the origin of the galaxy seeds around which galaxies,clusters,and walls grew?

Correct AnswerverifiedShow Answer

Which of the following applies if the universe is closed?

Correct AnswerverifiedShow Answer

Correct Answer
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Answered by ExamLex AI
The Big Bang theory is the prevailing co...
View Answer

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
verified

Correct Answer
Answered by ExamLex AI
A value of 100 km/sec/Mpc for the Hubble...
View Answer

Correct Answer
verified
cosmologic...
View Answer

Correct Answer
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Correct Answer
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D

Correct Answer
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A

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B

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