Question 1

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

Accepted Answer

A) 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. 
B) The temperature of the universe can be found by taking an average over the entire sky,but individual stars will create peaks in the spectrum over small angles. 
C) Dark matter consisting of WIMPs greatly smooths out the spectrum,but the small patches of "light" matter create peaks in the spectrum. 
D) The overall structure of the universe is very uniform,but the synthesis of different elements produces varying signatures within the background spectrum. 
E) 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. 
A) 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. 
B) The temperature of the universe can be found by taking an average over the entire sky,but individual stars will create peaks in the spectrum over small angles. 
C) Dark matter consisting of WIMPs greatly smooths out the spectrum,but the small patches of "light" matter create peaks in the spectrum. 
D) The overall structure of the universe is very uniform,but the synthesis of different elements produces varying signatures within the background spectrum. 
E) 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.

Question 2

We have conclusive evidence for inflation from the light polarization of the cosmic microwave background.

Accepted Answer

A) True 
 B)False

Question 3

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

Accepted Answer

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

Question 4

Which of the following statements cannot be tested by science today?

Accepted Answer

A) Our universe is flat. 
B) Prior to the Planck time,our universe sprouted from another universe. 
C) The universe is 14 billion years old. 
D) The expansion of the universe is now accelerating. 
A) Our universe is flat. 
B) Prior to the Planck time,our universe sprouted from another universe. 
C) The universe is 14 billion years old. 
D) The expansion of the universe is now accelerating.

Question 5

What is the significance of the Planck time?

Accepted Answer

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

Question 6

Refer to this scenario for the following questions:
Lost in Spacetime.Just when you thought it was safe to take final exams ...a vindictive multi-dimensional being reaches down (up? over? through?)to Earth and pulls you out of the universe.You are thrown back into the universe at a place of this being's choosing,and she permits you to leave only after you have identified your surroundings.You are subject to several tests.
Through a scientifically unexplainable miracle,you are able to survive in every one of the places you are tested.(Lest you become too comfortable,however,you certainly are able to feel any associated pain due to high temperature,pressure,gravity,etc. )In each case described below,identify your surroundings.In some cases,the surroundings described may exist only during eras of the universe (past or future)other than our own time;in those cases,you should identify both the place and the time where you are located.
-You are feeling like spaghetti.Although normally only about 2 meters tall,you are now about 25 meters long.(How fortunate,if painful,that the being has arranged for your body to become elastic enough so that it is not ripped apart under these conditions. )As you look up over your head,you see things moving pretty quickly in the universe-but that lasts only for a brief instant,and then all contact with the universe is lost.Where are you?

Accepted Answer

A) You are plunging into the Sun. 
B) You are crossing the event horizon of a black hole. 
C) You are being consumed by a "crack" in the universe caused by inflation. 
D) You are near the center of a star that has just developed an iron core,leading to a supernova. 
E) You are in a medieval torture chamber somewhere in western Europe. 
A) You are plunging into the Sun. 
B) You are crossing the event horizon of a black hole. 
C) You are being consumed by a "crack" in the universe caused by inflation. 
D) You are near the center of a star that has just developed an iron core,leading to a supernova. 
E) You are in a medieval torture chamber somewhere in western Europe.

Question 7

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

Accepted Answer

The two key pieces of evidence that supp

Question 8

The temperature variations of the cosmic microwave background observed by Planck agrees well with our model predictions.This provides persuasive evidence in favor of what?

Accepted Answer

A) both the Big Bang and inflation 
B) only the Big Bang,but not inflation 
C) not the Big Bang,but inflation 
D) neither the Big Bang nor inflation 
A) both the Big Bang and inflation 
B) only the Big Bang,but not inflation 
C) not the Big Bang,but inflation 
D) neither the Big Bang nor inflation

Question 9

Why is the era of nucleosynthesis so important in determining the chemical composition of the universe forever after?

Accepted Answer

The era of nucleosynthesis is important

Question 10

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

Accepted Answer

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

Question 11

The Planck era is another name for the present period of time in the universe.

Accepted Answer

A) True 
 B)False

Question 12

Which of the following statements correctly summarizes the events in the early universe according to the Big Bang theory?

Accepted Answer

A) The universe began with the forces unified.During the first fraction of a second,the forces separated and there was a brief but important episode of inflation.Subatomic particles of both matter and antimatter then began to appear from the energy present in the universe.Most of the particles annihilated to make photons,but some became protons,neutrons,electrons,and neutrinos.The protons and neutrons underwent some fusion during the first three minutes,thereby determining the basic chemical composition of the universe. 
B) An episode of what we call inflation initiated the event of the Big Bang.Once the Big Bang got underway,particles and forces began to appear one by one.The forces produced protons,which fused to make hydrogen and helium until the universe was about 380,000 years old.Then gravity began to act,turning the hydrogen and helium into galaxies. 
C) Forces and various subatomic particles began to appear during the first second after the Big Bang.For reasons not understood,the particles were all made of ordinary matter and none were made of antimatter,thus explaining why we live in a universe made of matter.The particles underwent some fusion for the first 380,000 years after the Big Bang,at which time the first stars were born. 
D) The Big Bang began with the initiation of what we call inflation,which gradually slowed to the current expansion rate of the universe.Forces came to exist for a different reason,having to do with quantum fluctuations in the space-time continuum.Particles came to exist as a result of cracks made when forces froze.Once there were particles,gravity brought them together to make stars,and the stars then turned the particles into hydrogen,helium,and other elements. 
A) The universe began with the forces unified.During the first fraction of a second,the forces separated and there was a brief but important episode of inflation.Subatomic particles of both matter and antimatter then began to appear from the energy present in the universe.Most of the particles annihilated to make photons,but some became protons,neutrons,electrons,and neutrinos.The protons and neutrons underwent some fusion during the first three minutes,thereby determining the basic chemical composition of the universe. 
B) An episode of what we call inflation initiated the event of the Big Bang.Once the Big Bang got underway,particles and forces began to appear one by one.The forces produced protons,which fused to make hydrogen and helium until the universe was about 380,000 years old.Then gravity began to act,turning the hydrogen and helium into galaxies. 
C) Forces and various subatomic particles began to appear during the first second after the Big Bang.For reasons not understood,the particles were all made of ordinary matter and none were made of antimatter,thus explaining why we live in a universe made of matter.The particles underwent some fusion for the first 380,000 years after the Big Bang,at which time the first stars were born. 
D) The Big Bang began with the initiation of what we call inflation,which gradually slowed to the current expansion rate of the universe.Forces came to exist for a different reason,having to do with quantum fluctuations in the space-time continuum.Particles came to exist as a result of cracks made when forces froze.Once there were particles,gravity brought them together to make stars,and the stars then turned the particles into hydrogen,helium,and other elements.

Question 13

Which of the following observations is not a piece of evidence supporting the Big Bang theory?

Accepted Answer

A) darkness of the night sky 
B) recession speeds of far away galaxies relative to close ones 
C) observed helium abundance in the universe 
D) relative motions of galaxies in the Local Group 
A) darkness of the night sky 
B) recession speeds of far away galaxies relative to close ones 
C) observed helium abundance in the universe 
D) relative motions of galaxies in the Local Group

Question 14

What are the two key observational facts that led to widespread acceptance of the Big Bang model?

Accepted Answer

A) the cosmic background radiation and the high helium content of the universe 
B) the cosmic background radiation and the expansion of the universe 
C) the cosmic background radiation and the near-critical density of the universe 
D) the predominance of matter over antimatter and the near-critical density of the universe 
E) the predominance of matter over antimatter and the large scale structure of galaxies 
A) the cosmic background radiation and the high helium content of the universe 
B) the cosmic background radiation and the expansion of the universe 
C) the cosmic background radiation and the near-critical density of the universe 
D) the predominance of matter over antimatter and the near-critical density of the universe 
E) the predominance of matter over antimatter and the large scale structure of galaxies

Question 15

Which of the following statements best explains what we mean when we say that the electroweak and strong forces "froze out" at 10⁻³⁸ second after the Big Bang?

Accepted Answer

A) These two forces first became distinct at this time. 
B) These forces are important only at temperatures below the freezing point of water-a temperature that the universe reached at an age of about at 10⁻³⁸ second. 
C) Freezing out was a term coined by particle physicists who think that the Big Bang theory is really cool. 
D) Following this time,neither the strong nor electroweak forces were ever important in the universe again. 
A) These two forces first became distinct at this time. 
B) These forces are important only at temperatures below the freezing point of water-a temperature that the universe reached at an age of about at 10⁻³⁸ second. 
C) Freezing out was a term coined by particle physicists who think that the Big Bang theory is really cool. 
D) Following this time,neither the strong nor electroweak forces were ever important in the universe again.

Question 16

Refer to this scenario for the following questions:
Lost in Spacetime.Just when you thought it was safe to take final exams ...a vindictive multi-dimensional being reaches down (up? over? through?)to Earth and pulls you out of the universe.You are thrown back into the universe at a place of this being's choosing,and she permits you to leave only after you have identified your surroundings.You are subject to several tests.
Through a scientifically unexplainable miracle,you are able to survive in every one of the places you are tested.(Lest you become too comfortable,however,you certainly are able to feel any associated pain due to high temperature,pressure,gravity,etc. )In each case described below,identify your surroundings.In some cases,the surroundings described may exist only during eras of the universe (past or future)other than our own time;in those cases,you should identify both the place and the time where you are located.
-You are in a place that is extremely hot and dense,making you feel quite sweaty and claustrophobic.You can't see far because your surroundings are opaque to light.Around you,nuclear fusion is converting carbon into oxygen and other elements.Where are you?

Accepted Answer

A) You are in the center of a star very much like our Sun. 
B) You are in the early universe during the era of nucleosynthesis. 
C) You are inside a nuclear power plant on Earth. 
D) You are in the center of a massive star near the end of its life. 
E) You are in the center of a star much smaller than the Sun. 
A) You are in the center of a star very much like our Sun. 
B) You are in the early universe during the era of nucleosynthesis. 
C) You are inside a nuclear power plant on Earth. 
D) You are in the center of a massive star near the end of its life. 
E) You are in the center of a star much smaller than the Sun.

Question 17

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

Accepted Answer

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

Question 18

If inflation really occurred,then our observable universe is only a tiny portion of the entire universe born in the Big Bang.

Accepted Answer

A) True 
 B)False

Question 19

Measuring the amount of deuterium in the universe allows us to set a limit on

Accepted Answer

A) the total amount of mass in the universe. 
B) the density of ordinary (baryonic)matter in the universe. 
C) the acceleration of the universe. 
D) the current age of the universe. 
A) the total amount of mass in the universe. 
B) the density of ordinary (baryonic)matter in the universe. 
C) the acceleration of the universe. 
D) the current age of the universe.

Question 20

To date,physicists have investigated the behavior of matter and energy at temperatures as high as those that existed in the universe as far back as ________ after the Big Bang.

Accepted Answer

A) 1 million years 
B) 300,000 years 
C) 300 years 
D) 3 minutes 
E) 10⁻¹⁰ second 
A) 1 million years 
B) 300,000 years 
C) 300 years 
D) 3 minutes 
E) 10⁻¹⁰ second

Exam 22: The Birth of the Universe

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

We have conclusive evidence for inflation from the light polarization of the cosmic microwave background.

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

Which of the following statements cannot be tested by science today?

What is the significance of the Planck time?

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

The temperature variations of the cosmic microwave background observed by Planck agrees well with our model predictions.This provides persuasive evidence in favor of what?

Why is the era of nucleosynthesis so important in determining the chemical composition of the universe forever after?

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

The Planck era is another name for the present period of time in the universe.

Which of the following statements correctly summarizes the events in the early universe according to the Big Bang theory?

Which of the following observations is not a piece of evidence supporting the Big Bang theory?

What are the two key observational facts that led to widespread acceptance of the Big Bang model?

Which of the following statements best explains what we mean when we say that the electroweak and strong forces "froze out" at 10⁻³⁸ second after the Big Bang?

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

If inflation really occurred,then our observable universe is only a tiny portion of the entire universe born in the Big Bang.

Measuring the amount of deuterium in the universe allows us to set a limit on

To date,physicists have investigated the behavior of matter and energy at temperatures as high as those that existed in the universe as far back as ________ after the Big Bang.

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

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

Life in the Universe

Celestial Timekeeping and Navigation

Space and Time

Spacetime and Gravity

Building Blocks of the Universe

Filters