Question 1

What do we mean by inflation?

Accepted Answer

A) the sudden release of photons when a particle and antiparticle annihilate one another 
B) quantum fluctuations by high speed, relativistic particles in a state of false vacuum that caused disturbances in the space- time continuum leading to the process described in the question to which this answer refers 
C) the expansion of the universe that we still observe today 
D) a sudden and extremely rapid expansion of the universe that occurred in a tiny fraction of a second during the universe's first second of existence 
A) the sudden release of photons when a particle and antiparticle annihilate one another 
B) quantum fluctuations by high speed, relativistic particles in a state of false vacuum that caused disturbances in the space- time continuum leading to the process described in the question to which this answer refers 
C) the expansion of the universe that we still observe today 
D) a sudden and extremely rapid expansion of the universe that occurred in a tiny fraction of a second during the universe's first second of existence

Question 2

Which of the following is not an observed characteristic of the cosmic microwave background?

Accepted Answer

A) It has a perfect thermal radiation spectrum. 
B) It contains prominent spectral lines of hydrogen, the primary chemical ingredient of the universe. 
C) Its temperature is a little less than 3 Kelvin (3 degrees above absolute zero). 
D) Its temperature is the same everywhere, except for small variations at the level of 1 part in 100,000. 
A) It has a perfect thermal radiation spectrum. 
B) It contains prominent spectral lines of hydrogen, the primary chemical ingredient of the universe. 
C) Its temperature is a little less than 3 Kelvin (3 degrees above absolute zero). 
D) Its temperature is the same everywhere, except for small variations at the level of 1 part in 100,000.

Question 3

Which of the following observations cannot be explained by the Big Bang theory unless we assume that an episode of inflation occurred?

Accepted Answer

A) the fact that the universe is expanding 
B) the fact that the temperature of the cosmic microwave background is almost the same everywhere 
C) the existence of the cosmic microwave background 
D) the fact that about 25% of the ordinary matter in the universe consists of helium 
A) the fact that the universe is expanding 
B) the fact that the temperature of the cosmic microwave background is almost the same everywhere 
C) the existence of the cosmic microwave background 
D) the fact that about 25% of the ordinary matter in the universe consists of helium

Question 4

Why do we expect the cosmic background radiation to be almost, but not quite, the same in all directions?

Accepted Answer

A) The temperature of the universe can be found by taking an average over the entire sky, but individual stars will create peaks in the temperature over small angles. 
B) The overall structure of the universe is very uniform, but the universe must have contained some regions of higher density in order for galaxies to form. 
C) The overall structure of the universe is very uniform, but intervening gas between us and the era of nuclei absorbs wavelengths depending on the composition and redshift of the gas. 
D) Dark matter will smooth out the spectrum, but the small patches of "light" matter create fluctuations in the temperature. 
E) The overall structure of the universe is very uniform, but the synthesis of different elements produces varying signatures within the background radiation. 
A) The temperature of the universe can be found by taking an average over the entire sky, but individual stars will create peaks in the temperature over small angles. 
B) The overall structure of the universe is very uniform, but the universe must have contained some regions of higher density in order for galaxies to form. 
C) The overall structure of the universe is very uniform, but intervening gas between us and the era of nuclei absorbs wavelengths depending on the composition and redshift of the gas. 
D) Dark matter will smooth out the spectrum, but the small patches of "light" matter create fluctuations in the temperature. 
E) The overall structure of the universe is very uniform, but the synthesis of different elements produces varying signatures within the background radiation.

Question 5

Early in the history of the universe, the universe was

Accepted Answer

A) the same temperature it is now. 
B) colder. 
C) hotter. 
A) the same temperature it is now. 
B) colder. 
C) hotter.

Question 6

Why can't current theories describe what happened during the Planck era?

Accepted Answer

A) We do not yet have a theory that links quantum mechanics and general relativity. 
B) We do not yet have a theory that explains how the universe underwent a rapid period of inflationary expansion. 
C) We do not yet have a theory that links the weak and electromagnetic forces. 
D) The Planck era was the time before the Big Bang, and we cannot describe what happened before the beginning of the universe. 
E) We do not understand the properties of the antimatter that would have been produced at this time. 
A) We do not yet have a theory that links quantum mechanics and general relativity. 
B) We do not yet have a theory that explains how the universe underwent a rapid period of inflationary expansion. 
C) We do not yet have a theory that links the weak and electromagnetic forces. 
D) The Planck era was the time before the Big Bang, and we cannot describe what happened before the beginning of the universe. 
E) We do not understand the properties of the antimatter that would have been produced at this time.

Question 7

Why did the Big Bang not produce heavier elements?

Accepted Answer

A) By the time helium could survive, the temperature had become too low for heavier elements to form. 
B) They did, but radioactive decay caused these elements to disappear again. 
C) Too many high energy photons were present during the era of nucleosynthesis for heavy elements to form. 
A) By the time helium could survive, the temperature had become too low for heavier elements to form. 
B) They did, but radioactive decay caused these elements to disappear again. 
C) Too many high energy photons were present during the era of nucleosynthesis for heavy elements to form.

Question 8

What is the significance of the Planck time?

Accepted Answer

A) It is the amount of time required for two protons to fuse to make deuterium. 
B) It is the time at which inflation is thought to have occurred. 
C) Before it, conditions were so extreme that our current understanding of physics is insufficient to predict what might have occurred. 
D) It is the time when the cosmic microwave background was released. 
A) It is the amount of time required for two protons to fuse to make deuterium. 
B) It is the time at which inflation is thought to have occurred. 
C) Before it, conditions were so extreme that our current understanding of physics is insufficient to predict what might have occurred. 
D) It is the time when the cosmic microwave background was released.

Question 9

Which of the following statements about the cosmic background radiation is not true?

Accepted Answer

A) It had a much higher temperature in the past. 
B) It was discovered by Penzias and Wilson in the mid- 1960s. 
C) It has a temperature of about 3 degrees K above absolute zero. 
D) It appears essentially the same in all directions (it is isotropic). 
E) It is the result of a mixture of radiation from many independent sources, such as stars and galaxies that formed within the first billion years of the Big Bang. 
A) It had a much higher temperature in the past. 
B) It was discovered by Penzias and Wilson in the mid- 1960s. 
C) It has a temperature of about 3 degrees K above absolute zero. 
D) It appears essentially the same in all directions (it is isotropic). 
E) It is the result of a mixture of radiation from many independent sources, such as stars and galaxies that formed within the first billion years of the Big Bang.

Question 10

A GUT (grand unified theory)refers to theories that

Accepted Answer

A) unify gravity and the electromagnetic and weak forces. 
B) unify the strong force and the electromagnetic and weak forces. 
C) unify gravity and the strong and weak forces. 
D) unify all four forces. 
E) unify the electromagnetic and weak forces. 
A) unify gravity and the electromagnetic and weak forces. 
B) unify the strong force and the electromagnetic and weak forces. 
C) unify gravity and the strong and weak forces. 
D) unify all four forces. 
E) unify the electromagnetic and weak forces.

Question 11

Why might inflation have occurred at the end of the GUT era?

Accepted Answer

A) An enormous amount of energy was released when the strong and electroweak forces froze out from the GUT force. 
B) Large amounts of matter and antimatter annihilated at this time. 
C) Gravity was an extremely weak force at this period in time. 
D) The universe was too small and needed to grow quickly. 
E) There wasn't enough matter present to slow down the expansion at that time. 
A) An enormous amount of energy was released when the strong and electroweak forces froze out from the GUT force. 
B) Large amounts of matter and antimatter annihilated at this time. 
C) Gravity was an extremely weak force at this period in time. 
D) The universe was too small and needed to grow quickly. 
E) There wasn't enough matter present to slow down the expansion at that time.

Question 12

Briefly describe the two key pieces of evidence that support the Big Bang theory.

Accepted Answer

The Big Bang theory predicts that the un

Question 13

Briefly explain why radiation was trapped for 380,000 years during the era of nuclei, and why the cosmic background radiation was formed at the end of this era.

Accepted Answer

During the era of nuclei, the universe c

Question 14

Why does the Big Bang theory predict that the cosmic background radiation should have a perfect thermal radiation spectrum?

Accepted Answer

A) The spectrum of pure hydrogen gas must be a perfect thermal radiation spectrum. 
B) The background radiation came from the heat of the universe, with a peak corresponding to the temperature of the universe. 
C) The spectrum of 75 percent hydrogen and 25 percent helium must be a perfect thermal radiation spectrum. 
D) The light from all the stars and gas in the sky averaged over the entire universe will be a perfect thermal radiation spectrum. 
E) It doesn't predict that the cosmic background radiation should have a perfect thermal radiation spectrum. 
A) The spectrum of pure hydrogen gas must be a perfect thermal radiation spectrum. 
B) The background radiation came from the heat of the universe, with a peak corresponding to the temperature of the universe. 
C) The spectrum of 75 percent hydrogen and 25 percent helium must be a perfect thermal radiation spectrum. 
D) The light from all the stars and gas in the sky averaged over the entire universe will be a perfect thermal radiation spectrum. 
E) It doesn't predict that the cosmic background radiation should have a perfect thermal radiation spectrum.

Question 15

The Big Bang theory is supported by two major lines of evidence that alternative models have not successfully explained. What are they?

Accepted Answer

A) (1)The theory predicts the existence of and the specific characteristics of the observed cosmic microwave background; (2)the theory correctly predicts the observed overall chemical composition of the universe. 
B) (1)The theory correctly predicts that the universe should be expanding; (2)the theory predicts the existence of and the specific characteristics of the observed cosmic microwave background. 
C) (1)The theory predicts the episode of inflation that we think occurred in the early universe; (2)the theory predicts the existence of large quantities of dark matter. 
D) (1)The theory correctly predicts that the universe should be expanding; (2)the theory correctly predicts the observed ratio of spiral to elliptical galaxies in the universe. 
A) (1)The theory predicts the existence of and the specific characteristics of the observed cosmic microwave background; (2)the theory correctly predicts the observed overall chemical composition of the universe. 
B) (1)The theory correctly predicts that the universe should be expanding; (2)the theory predicts the existence of and the specific characteristics of the observed cosmic microwave background. 
C) (1)The theory predicts the episode of inflation that we think occurred in the early universe; (2)the theory predicts the existence of large quantities of dark matter. 
D) (1)The theory correctly predicts that the universe should be expanding; (2)the theory correctly predicts the observed ratio of spiral to elliptical galaxies in the universe.

Question 16

What direct evidence do we have that the weak and electromagnetic forces were once unified as a single force?

Accepted Answer

A) Particle accelerators on Earth can reach energies equivalent to the high temperatures of the Electroweak era and have produced particles predicted by the unified theory. 
B) Temperatures in the center of the Sun can reproduce the conditions during the Electroweak era. 
C) The most advanced telescopes are able to see back to the GUT era in the universe. 
D) Detectors on Earth have received photons and high- energy particles from the GUT era. 
E) We have no direct evidence of such a unified force. 
A) Particle accelerators on Earth can reach energies equivalent to the high temperatures of the Electroweak era and have produced particles predicted by the unified theory. 
B) Temperatures in the center of the Sun can reproduce the conditions during the Electroweak era. 
C) The most advanced telescopes are able to see back to the GUT era in the universe. 
D) Detectors on Earth have received photons and high- energy particles from the GUT era. 
E) We have no direct evidence of such a unified force.

Question 17

If observations had shown that the cosmic microwave background was perfectly smooth (rather than having very slight variations in temperature), then we would have no way to account for .

Accepted Answer

A) the relationship between the strong and the weak force 
B) how galaxies came to exist 
C) the fact that our universe is expanding 
D) the existence of helium in the universe 
A) the relationship between the strong and the weak force 
B) how galaxies came to exist 
C) the fact that our universe is expanding 
D) the existence of helium in the universe

Question 18

Olbers' paradox is an apparently simple question, but its resolution suggests that the universe is finite in age. What is the simple question posed by Olbers' paradox?

Accepted Answer

A) How many stars are in the universe? 
B) What would it be like to ride on a beam of light? 
C) Why is the sky dark at night? 
D) Can we measure the position and momentum of an electron at the same time? 
E) How does the Sun produce energy? 
A) How many stars are in the universe? 
B) What would it be like to ride on a beam of light? 
C) Why is the sky dark at night? 
D) Can we measure the position and momentum of an electron at the same time? 
E) How does the Sun produce energy?

Question 19

Galaxies formed from tiny density perturbations that formed prior to the inflationary period.

Accepted Answer

A) True 
 B)False

Question 20

What is Olbers' paradox, and what is its resolution?

Accepted Answer

If the universe were infinite and unchan

What do we mean by inflation?

Which of the following is not an observed characteristic of the cosmic microwave background?

Which of the following observations cannot be explained by the Big Bang theory unless we assume that an episode of inflation occurred?

Why do we expect the cosmic background radiation to be almost, but not quite, the same in all directions?

Early in the history of the universe, the universe was

Why can't current theories describe what happened during the Planck era?

Why did the Big Bang not produce heavier elements?

What is the significance of the Planck time?

Which of the following statements about the cosmic background radiation is not true?

A GUT (grand unified theory)refers to theories that

Why might inflation have occurred at the end of the GUT era?

Briefly describe the two key pieces of evidence that support the Big Bang theory.

Briefly explain why radiation was trapped for 380,000 years during the era of nuclei, and why the cosmic background radiation was formed at the end of this era.

Why does the Big Bang theory predict that the cosmic background radiation should have a perfect thermal radiation spectrum?

The Big Bang theory is supported by two major lines of evidence that alternative models have not successfully explained. What are they?

What direct evidence do we have that the weak and electromagnetic forces were once unified as a single force?

If observations had shown that the cosmic microwave background was perfectly smooth (rather than having very slight variations in temperature), then we would have no way to account for .

Olbers' paradox is an apparently simple question, but its resolution suggests that the universe is finite in age. What is the simple question posed by Olbers' paradox?

Galaxies formed from tiny density perturbations that formed prior to the inflationary period.

What is Olbers' paradox, and what is its resolution?

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: the Cosmic Messenger

Formation of the Solar System

Earth and the Terrestrial Worlds

Jovian Planet System

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 Stuff

The Bizarre Stellar Graveyard

Our Galaxy

A Universe of Galaxies

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

Life in the Universe

Filters

Exam 17: The Birth of the Universe

What do we mean by inflation?

Which of the following is not an observed characteristic of the cosmic microwave background?

Which of the following observations cannot be explained by the Big Bang theory unless we assume that an episode of inflation occurred?

Why do we expect the cosmic background radiation to be almost, but not quite, the same in all directions?

Early in the history of the universe, the universe was

Why can't current theories describe what happened during the Planck era?

Why did the Big Bang not produce heavier elements?

What is the significance of the Planck time?

Which of the following statements about the cosmic background radiation is not true?

A GUT (grand unified theory)refers to theories that

Why might inflation have occurred at the end of the GUT era?

Briefly describe the two key pieces of evidence that support the Big Bang theory.

Briefly explain why radiation was trapped for 380,000 years during the era of nuclei, and why the cosmic background radiation was formed at the end of this era.

Why does the Big Bang theory predict that the cosmic background radiation should have a perfect thermal radiation spectrum?

The Big Bang theory is supported by two major lines of evidence that alternative models have not successfully explained. What are they?

What direct evidence do we have that the weak and electromagnetic forces were once unified as a single force?

If observations had shown that the cosmic microwave background was perfectly smooth (rather than having very slight variations in temperature), then we would have no way to account for .

Olbers' paradox is an apparently simple question, but its resolution suggests that the universe is finite in age. What is the simple question posed by Olbers' paradox?

Galaxies formed from tiny density perturbations that formed prior to the inflationary period.

What is Olbers' paradox, and what is its resolution?

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: the Cosmic Messenger

Formation of the Solar System

Earth and the Terrestrial Worlds

Jovian Planet System

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 Stuff

The Bizarre Stellar Graveyard

Our Galaxy

A Universe of Galaxies

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

Life in the Universe

Filters