Question 1

What kinds of atomic nuclei formed during the nucleosynthesis era?

Accepted Answer

A)  only hydrogen 
B)  only helium 
C)  hydrogen, helium and trace amounts of lithium, beryllium, and boron 
D)  roughly equal amounts of hydrogen, helium, lithium, beryllium, and boron 
E)  essentially all of the chemical elements, except for those heavier than uranium 
A)  only hydrogen 
B)  only helium 
C)  hydrogen, helium and trace amounts of lithium, beryllium, and boron 
D)  roughly equal amounts of hydrogen, helium, lithium, beryllium, and boron 
E)  essentially all of the chemical elements, except for those heavier than uranium

Question 2

Current measurements of the matter density of the universe (including dark matter) support the prediction of the theory of inflation that the universe should be flat.

Accepted Answer

A) True 
 B)False

Question 3

How long after the Big Bang was the Planck time, the time at which our current theories become completely unable to describe conditions any earlier in the universe?

Accepted Answer

A)  10⁻¹⁰ seconds 
B)  10⁻³⁵ seconds 
C)  10⁻⁴³ seconds 
D)  3 minutes 
E)  380,000 years 
A)  10⁻¹⁰ seconds 
B)  10⁻³⁵ seconds 
C)  10⁻⁴³ seconds 
D)  3 minutes 
E)  380,000 years

Question 4

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

Accepted Answer

A)  the temperature of the universe at the end of the era of nuclei. 
B)  the total amount of mass in the universe. 
C)  the density of ordinary (baryonic) matter in the universe. 
D)  the expansion rate of the universe. 
E)  the current age of the universe. 
A)  the temperature of the universe at the end of the era of nuclei. 
B)  the total amount of mass in the universe. 
C)  the density of ordinary (baryonic) matter in the universe. 
D)  the expansion rate of the universe. 
E)  the current age of the universe.

Question 5

How do we determine the conditions that existed in the very early universe?

Accepted Answer

A)  We work backward from current conditions to calculate what temperatures and densities must have been when the observable universe was much smaller in size. 
B)  We look all the way to the cosmological horizon, where we can see the actual conditions that prevailed all the way back to the first instant of the Big Bang. 
C)  The conditions in the very early universe must have been much like those found in stars today, so we learn about them by studying stars. 
D)  We can only guess at the conditions, since we have no way to calculate or observe what they were. 
A)  We work backward from current conditions to calculate what temperatures and densities must have been when the observable universe was much smaller in size. 
B)  We look all the way to the cosmological horizon, where we can see the actual conditions that prevailed all the way back to the first instant of the Big Bang. 
C)  The conditions in the very early universe must have been much like those found in stars today, so we learn about them by studying stars. 
D)  We can only guess at the conditions, since we have no way to calculate or observe what they were.

Question 6

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 7

Based on the observed amount of deuterium in the universe, we can conclude that

Accepted Answer

A)  ordinary (baryonic) matter makes 75 percent of the mass of the universe. 
B)  neutrons outnumber protons 7 to 1 in the universe. 
C)  most of the deuterium that was created during the era of nucleosynthesis has since been destroyed. 
D)  the density of ordinary (baryonic) matter is about 4 percent of the critical density. 
E)  we live in a critical-density universe. 
A)  ordinary (baryonic) matter makes 75 percent of the mass of the universe. 
B)  neutrons outnumber protons 7 to 1 in the universe. 
C)  most of the deuterium that was created during the era of nucleosynthesis has since been destroyed. 
D)  the density of ordinary (baryonic) matter is about 4 percent of the critical density. 
E)  we live in a critical-density universe.

Question 8

The four fundamental forces that operate in the universe today are ________.

Accepted Answer

A)  strong force, weak force, electromagnetic force, gravity 
B)  strong force, weak force, electric force, magnetic force 
C)  nuclear force, electromagnetic force, gravity, tidal force 
D)  nuclear force, gravity, electric force, magnetic force 
A)  strong force, weak force, electromagnetic force, gravity 
B)  strong force, weak force, electric force, magnetic force 
C)  nuclear force, electromagnetic force, gravity, tidal force 
D)  nuclear force, gravity, electric force, magnetic force

Question 9

The Cosmic Microwave Background Radiation: The CMBR is one of the true observational bonanzas of 20ᵗʰ and 21ˢᵗ-century astronomy. Make as complete a list as possible of the various observations of the cosmic microwave background that have been used to confirm, challenge, and extend the Big Bang theory for the origin and evolution of the Universe.

Accepted Answer

1. Penzias and Wilson's discovery in 196

Question 10

Early in the history of the universe, the universe was

Accepted Answer

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

Question 11

Evidence that the cosmic background radiation is the remnant of a Big Bang comes from predicting characteristics of remnant radiation from the Big Bang theory and comparing these predictions with observations. Four of the five statements below are real. Which one is fictitious?

Accepted Answer

A)  The cosmic background radiation is expected to have a temperature just a few degrees above absolute zero, and its actual temperature turns out to be 2.73 K. 
B)  The cosmic background radiation is expected to have a perfect thermal spectrum, and observations from the COBE spacecraft verify this prediction. 
C)  The cosmic background radiation is expected to contain redshifted emission lines from hydrogen and helium, and it does. 
D)  The cosmic background radiation is expected to look essentially the same in all directions, and it does. 
E)  The cosmic background radiation is expected to have tiny temperature fluctuations at the level of about 1 part in 100,000. Such fluctuations were found in the COBE data. 
A)  The cosmic background radiation is expected to have a temperature just a few degrees above absolute zero, and its actual temperature turns out to be 2.73 K. 
B)  The cosmic background radiation is expected to have a perfect thermal spectrum, and observations from the COBE spacecraft verify this prediction. 
C)  The cosmic background radiation is expected to contain redshifted emission lines from hydrogen and helium, and it does. 
D)  The cosmic background radiation is expected to look essentially the same in all directions, and it does. 
E)  The cosmic background radiation is expected to have tiny temperature fluctuations at the level of about 1 part in 100,000. Such fluctuations were found in the COBE data.

Question 12

The more baryons there are in the universe (a higher density of baryonic matter), the lower the ratio of deuterium to hydrogen is. Therefore, if Harry measures a higher ratio of deuterium to hydrogen than Sally, Harry infers

Accepted Answer

A)  the same density of baryons as Sally. 
B)  a lower density of baryons than Sally. 
C)  a higher density of baryons than Sally. 
A)  the same density of baryons as Sally. 
B)  a lower density of baryons than Sally. 
C)  a higher density of baryons than Sally.

Question 13

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 know how hot or dense the universe was during that time. 
C)  We do not understand the properties of antimatter. 
D)  The Planck era was the time before the Big Bang, and we cannot describe what happened before that instant. 
A)  We do not yet have a theory that links quantum mechanics and general relativity. 
B)  We do not know how hot or dense the universe was during that time. 
C)  We do not understand the properties of antimatter. 
D)  The Planck era was the time before the Big Bang, and we cannot describe what happened before that instant.

Question 14

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

Question 15

What is the temperature of the universe (as a whole) today?

Accepted Answer

A)  3K 
B)  3000K 
C)  300K 
D)  The universe cannot be said to have a single temperature. 
A)  3K 
B)  3000K 
C)  300K 
D)  The universe cannot be said to have a single temperature.

Question 16

According to the Big Bang theory, why do we live in a universe that is made of almost entirely of matter rather than antimatter?

Accepted Answer

A)  During the first 0.001 second after the Big Bang, particles and antiparticles were made in almost but not perfectly equal numbers. Everything annihilated except the very slight excess of matter particles. 
B)  GUT theories predict that under the conditions that prevailed in the early universe, the normal laws of physics would have been suspended so that only matter particles were created, and no particles of antimatter. 
C)  The fact that we live in a universe made of matter is not surprising, because antimatter has never been shown to exist for real. 
D)  Einstein's famous equation E = mc² tells us that energy can turn into matter, but does not tell us that it can turn into antimatter. 
A)  During the first 0.001 second after the Big Bang, particles and antiparticles were made in almost but not perfectly equal numbers. Everything annihilated except the very slight excess of matter particles. 
B)  GUT theories predict that under the conditions that prevailed in the early universe, the normal laws of physics would have been suspended so that only matter particles were created, and no particles of antimatter. 
C)  The fact that we live in a universe made of matter is not surprising, because antimatter has never been shown to exist for real. 
D)  Einstein's famous equation E = mc² tells us that energy can turn into matter, but does not tell us that it can turn into antimatter.

Question 17

Refer to this scenario for the following questions:
A multi-dimensional being reaches down to Earth and pulls you out of the universe. You are then thrown back into the universe at a place and time of the being's choosing, and you are permitted to leave only after you have identified your surroundings. This process is repeated several times. Through a scientifically unexplainable miracle, you are able to survive in every one of the places that you find yourself. In each scenario below, identify your surroundings (and potentially your cosmic era) from among the choices given.
-You find yourself in a very low-density gas that is extremely hot. In fact, the temperature of the gas is so high that it is emitting lots of X-rays. There are no stars anywhere within about 10,000 light-years of you, but at slightly greater distances, your sky is brightened by hundreds (perhaps thousands) of beautiful, star-filled structures, some with majestic spiral shapes. Where are you?

Accepted Answer

A)  You are in the universe when it was about 500 million years old, just before galaxies began to form. 
B)  You are in the center of the Milky Way Galaxy, looking outward into the Local Group. 
C)  You are in the universe about 380,000 years after the Big Bang when the cosmic microwave background radiation was formed. 
D)  You are in intergalactic space within a rich cluster of thousands of galaxies. 
E)  You are in the outskirts of a galaxy whose nucleus is a powerful quasar. 
A)  You are in the universe when it was about 500 million years old, just before galaxies began to form. 
B)  You are in the center of the Milky Way Galaxy, looking outward into the Local Group. 
C)  You are in the universe about 380,000 years after the Big Bang when the cosmic microwave background radiation was formed. 
D)  You are in intergalactic space within a rich cluster of thousands of galaxies. 
E)  You are in the outskirts of a galaxy whose nucleus is a powerful quasar.

Question 18

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

Accepted Answer

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

Question 19

Based on our current understanding of physics, we can understand the conditions that prevailed in the early universe as far back in time as about ________.

Accepted Answer

A)  one ten-billionth of a second after the Big Bang 
B)  380,000 years after the Big Bang 
C)  10⁻⁴⁵ seconds after the Big Bang 
D)  10 billion years ago 
A)  one ten-billionth of a second after the Big Bang 
B)  380,000 years after the Big Bang 
C)  10⁻⁴⁵ seconds after the Big Bang 
D)  10 billion years ago

Question 20

Which of the following is not consistent with observations of the cosmic microwave background?

Accepted Answer

A)  The universe is geometrically "flat" (in the four dimensions of spacetime). 
B)  The matter density (both luminous and dark matter combined) in the universe is only about one-fourth of the critical density. 
C)  Dark energy, whatever it is, represents the majority of the energy content of the universe. 
D)  The universe is at least 20 billion years old. 
A)  The universe is geometrically "flat" (in the four dimensions of spacetime). 
B)  The matter density (both luminous and dark matter combined) in the universe is only about one-fourth of the critical density. 
C)  Dark energy, whatever it is, represents the majority of the energy content of the universe. 
D)  The universe is at least 20 billion years old.

What kinds of atomic nuclei formed during the nucleosynthesis era?

Current measurements of the matter density of the universe (including dark matter) support the prediction of the theory of inflation that the universe should be flat.

How long after the Big Bang was the Planck time, the time at which our current theories become completely unable to describe conditions any earlier in the universe?

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

How do we determine the conditions that existed in the very early universe?

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.

Based on the observed amount of deuterium in the universe, we can conclude that

The four fundamental forces that operate in the universe today are ________.

Early in the history of the universe, the universe was

Evidence that the cosmic background radiation is the remnant of a Big Bang comes from predicting characteristics of remnant radiation from the Big Bang theory and comparing these predictions with observations. Four of the five statements below are real. Which one is fictitious?

The more baryons there are in the universe (a higher density of baryonic matter), the lower the ratio of deuterium to hydrogen is. Therefore, if Harry measures a higher ratio of deuterium to hydrogen than Sally, Harry infers

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

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

What is the temperature of the universe (as a whole) today?

According to the Big Bang theory, why do we live in a universe that is made of almost entirely of matter rather than antimatter?

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

Based on our current understanding of physics, we can understand the conditions that prevailed in the early universe as far back in time as about ________.

Which of the following is not consistent with observations of the cosmic microwave background?

Our Place in 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 Planetary Systems: Our Solar System and Beyond

Earth and the Terrestrial Worlds

Jovian Planet Systems

Asteroids, Comets, and Dwarf Planets: Their Nature, Orbits, and Impacts

Our Star

Surveying the Stars

Star Stuff

Bizarre Stellar Graveyard

Our Galaxy

Galaxies and the Foundation of Modern Cosmology

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

Life in the Universe

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Exam 17: The Beginning of Time

What kinds of atomic nuclei formed during the nucleosynthesis era?

Current measurements of the matter density of the universe (including dark matter) support the prediction of the theory of inflation that the universe should be flat.

How long after the Big Bang was the Planck time, the time at which our current theories become completely unable to describe conditions any earlier in the universe?

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

How do we determine the conditions that existed in the very early universe?

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.

Based on the observed amount of deuterium in the universe, we can conclude that

The four fundamental forces that operate in the universe today are ________.

Early in the history of the universe, the universe was

Evidence that the cosmic background radiation is the remnant of a Big Bang comes from predicting characteristics of remnant radiation from the Big Bang theory and comparing these predictions with observations. Four of the five statements below are real. Which one is fictitious?

The more baryons there are in the universe (a higher density of baryonic matter), the lower the ratio of deuterium to hydrogen is. Therefore, if Harry measures a higher ratio of deuterium to hydrogen than Sally, Harry infers

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

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

What is the temperature of the universe (as a whole) today?

According to the Big Bang theory, why do we live in a universe that is made of almost entirely of matter rather than antimatter?

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

Based on our current understanding of physics, we can understand the conditions that prevailed in the early universe as far back in time as about ________.

Which of the following is not consistent with observations of the cosmic microwave background?

Our Place in 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 Planetary Systems: Our Solar System and Beyond

Earth and the Terrestrial Worlds

Jovian Planet Systems

Asteroids, Comets, and Dwarf Planets: Their Nature, Orbits, and Impacts

Our Star

Surveying the Stars

Star Stuff

Bizarre Stellar Graveyard

Our Galaxy

Galaxies and the Foundation of Modern Cosmology

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

Life in the Universe

Filters