Question 1

How long after the Big Bang was the Planck time,before which our current theories are completely unable to describe conditions in the universe?

Accepted Answer

A) 10⁻¹⁰ second 
B) 10⁻³⁵ second 
C) 10⁻⁴³ second 
D) 3 minutes 
E) 300,000 years 
A) 10⁻¹⁰ second 
B) 10⁻³⁵ second 
C) 10⁻⁴³ second 
D) 3 minutes 
E) 300,000 years

Question 2

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

Accepted Answer

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

Question 3

The idea of inflation makes one clear prediction that,until the discovery of an accelerating expansion,seemed to contradict the available observations.What is this prediction?

Accepted Answer

A) Inflation predicts that the early universe should have regions of enhanced density that could have acted as "seeds" for the formation of galaxies and large structures. 
B) The universe should be geometrically "flat" (in the four dimensions of spacetime). 
C) Inflation predicts that the temperature of the cosmic microwave background should be almost (but not exactly)the same everywhere. 
D) Inflation predicts that the entire universe must be far larger than the observable universe. 
A) Inflation predicts that the early universe should have regions of enhanced density that could have acted as "seeds" for the formation of galaxies and large structures. 
B) The universe should be geometrically "flat" (in the four dimensions of spacetime). 
C) Inflation predicts that the temperature of the cosmic microwave background should be almost (but not exactly)the same everywhere. 
D) Inflation predicts that the entire universe must be far larger than the observable universe.

Question 4

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

Accepted Answer

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

Question 5

The observed composition of ordinary matter in the universe-roughly 75 percent hydrogen and 25 percent helium-closely matches theoretical predictions based on the Big Bang model.

Accepted Answer

A) True 
 B)False

Question 6

How does the idea of inflation account for the existence of the "seeds" of density from which galaxies and other large structures formed?

Accepted Answer

A) Inflation predicts that gravity would have been very strong and thereby would have concentrated mass into seeds. 
B) Inflation tells us that the universe should have a "flat" overall geometry,and this led to the flat disks of galaxies. 
C) Inflation predicts that temperatures and densities should have become nearly equal throughout the universe. 
D) Inflation would have caused random,microscopic quantum fluctuations to grow so large in size that they became the seeds of structure. 
A) Inflation predicts that gravity would have been very strong and thereby would have concentrated mass into seeds. 
B) Inflation tells us that the universe should have a "flat" overall geometry,and this led to the flat disks of galaxies. 
C) Inflation predicts that temperatures and densities should have become nearly equal throughout the universe. 
D) Inflation would have caused random,microscopic quantum fluctuations to grow so large in size that they became the seeds of structure.

Question 7

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

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.

Question 8

A "GUT" (grand unified theory)refers to theories that

Accepted Answer

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

Question 9

A GUT (grand unified theory)refers to theories that

Accepted Answer

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

Question 10

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 find yourself in a place that looks (except for your own presence)perfectly symmetrical.There is no way to distinguish one place from another,and all forces are one.With this perfect symmetry,there is no obvious way to define the flow of time.Where are you?

Accepted Answer

A) You are in the center of a young star. 
B) You are in the early universe before the Planck time. 
C) You are floating somewhere in the universe near its end,10¹⁰⁰ years from now. 
D) You are inside the nucleus of an atom. 
E) You are in the universe shortly after inflation. 
A) You are in the center of a young star. 
B) You are in the early universe before the Planck time. 
C) You are floating somewhere in the universe near its end,10¹⁰⁰ years from now. 
D) You are inside the nucleus of an atom. 
E) You are in the universe shortly after inflation.

Question 11

What happens when a particle of matter meets its corresponding antiparticle of antimatter?

Accepted Answer

A) They can form a complete atom. 
B) The combined mass of the two particles is completely transformed into energy (photons). 
C) They fuse to make a heavier particle. 
D) The question makes no sense,since antimatter does not really exist. 
A) They can form a complete atom. 
B) The combined mass of the two particles is completely transformed into energy (photons). 
C) They fuse to make a heavier particle. 
D) The question makes no sense,since antimatter does not really exist.

Question 12

The idea of dark matter arose to explain gravitational effects observed in galaxies and clusters of galaxies.However,studies of the early universe (especially of the cosmic microwave background and of chemical abundances)also tell us something about dark matter.What do they tell us?

Accepted Answer

A) They add further support to the idea that dark matter really exists and is made of non-ordinary (nonbaryonic)matter,such as WIMPs. 
B) They do not support the conclusion that dark matter is the dominant form of matter in the universe. 
C) They tell us that dark matter probably exists,but that it must be made of ordinary (baryonic)matter in the form of MACHOs. 
D) They tell us that dark matter was produced during the era of nuclei. 
A) They add further support to the idea that dark matter really exists and is made of non-ordinary (nonbaryonic)matter,such as WIMPs. 
B) They do not support the conclusion that dark matter is the dominant form of matter in the universe. 
C) They tell us that dark matter probably exists,but that it must be made of ordinary (baryonic)matter in the form of MACHOs. 
D) They tell us that dark matter was produced during the era of nuclei.

Question 13

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

Accepted Answer

A) 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. 
B) 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. 
C) We work backward from current conditions to calculate what temperatures and densities must have been when the observable universe was much smaller in size. 
D) We can only guess at the conditions,since we have no way to calculate or observe what they were. 
A) 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. 
B) 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. 
C) We work backward from current conditions to calculate what temperatures and densities must have been when the observable universe was much smaller in size. 
D) We can only guess at the conditions,since we have no way to calculate or observe what they were.

Question 14

Which adjective does not necessarily describe a known feature of the early universe? (Be sure to consider the universe as a whole,not just the observable universe. )

Accepted Answer

A) dense 
B) small 
C) hot 
D) filled with intense radiation 
A) dense 
B) small 
C) hot 
D) filled with intense radiation

Question 15

The Planck era refers to the time period

Accepted Answer

A) before the Big Bang. 
B) before the Planck time. 
C) after the Planck time. 
D) after inflation. 
E) after the GUT era. 
A) before the Big Bang. 
B) before the Planck time. 
C) after the Planck time. 
D) after inflation. 
E) after the GUT era.

Question 16

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

Question 17

In stars,helium can sometimes be fused into carbon and heavier elements (in their final stages of life).Why didn't the same fusion processes produce carbon and heavier elements in the early universe?

Accepted Answer

A) By the time stable helium nuclei had formed,the temperature and density had already dropped too low for helium fusion to occur. 
B) Helium fusion occurred,but the carbon nuclei that were made were later destroyed by the intense radiation in the early universe. 
C) Temperatures in the early universe were never above the roughly 100 million Kelvin required for helium fusion. 
D) No one knows-this is one of the major mysteries in astronomy. 
A) By the time stable helium nuclei had formed,the temperature and density had already dropped too low for helium fusion to occur. 
B) Helium fusion occurred,but the carbon nuclei that were made were later destroyed by the intense radiation in the early universe. 
C) Temperatures in the early universe were never above the roughly 100 million Kelvin required for helium fusion. 
D) No one knows-this is one of the major mysteries in astronomy.

Question 18

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 understand the properties of antimatter. 
C) We do not know how much energy existed during that time. 
D) It was a time period from which we cannot receive radiation. 
E) 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 understand the properties of antimatter. 
C) We do not know how much energy existed during that time. 
D) It was a time period from which we cannot receive radiation. 
E) The Planck era was the time before the Big Bang,and we cannot describe what happened before that instant.

Question 19

Why do we think tiny quantum ripples should have been present in the very early universe?

Accepted Answer

A) The shock wave of the Big Bang caused ripples that expanded outward with time. 
B) The energy released when the strong force froze out of the GUT force caused shock waves that produced ripples in the universe. 
C) Matter and antimatter particles that spontaneously formed from high-energy photons caused perturbations in the radiation field. 
D) The annihilation of matter and antimatter particles caused tiny explosions that perturbed the radiation field. 
E) Quantum mechanics requires that the energy fields at any point in space be continually fluctuating as a result of the uncertainty principle. 
A) The shock wave of the Big Bang caused ripples that expanded outward with time. 
B) The energy released when the strong force froze out of the GUT force caused shock waves that produced ripples in the universe. 
C) Matter and antimatter particles that spontaneously formed from high-energy photons caused perturbations in the radiation field. 
D) The annihilation of matter and antimatter particles caused tiny explosions that perturbed the radiation field. 
E) Quantum mechanics requires that the energy fields at any point in space be continually fluctuating as a result of the uncertainty principle.

Question 20

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 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. 
B) (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. 
C) (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. 
D) (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. 
A) (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. 
B) (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. 
C) (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. 
D) (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.

Exam 22: The Birth of the Universe

How long after the Big Bang was the Planck time,before which our current theories are completely unable to describe conditions in the universe?

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

The idea of inflation makes one clear prediction that,until the discovery of an accelerating expansion,seemed to contradict the available observations.What is this prediction?

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

The observed composition of ordinary matter in the universe-roughly 75 percent hydrogen and 25 percent helium-closely matches theoretical predictions based on the Big Bang model.

How does the idea of inflation account for the existence of the "seeds" of density from which galaxies and other large structures formed?

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

A "GUT" (grand unified theory)refers to theories that

A GUT (grand unified theory)refers to theories that

What happens when a particle of matter meets its corresponding antiparticle of antimatter?

The idea of dark matter arose to explain gravitational effects observed in galaxies and clusters of galaxies.However,studies of the early universe (especially of the cosmic microwave background and of chemical abundances)also tell us something about dark matter.What do they tell us?

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

Which adjective does not necessarily describe a known feature of the early universe? (Be sure to consider the universe as a whole,not just the observable universe. )

The Planck era refers to the time period

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

In stars,helium can sometimes be fused into carbon and heavier elements (in their final stages of life).Why didn't the same fusion processes produce carbon and heavier elements in the early universe?

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

Why do we think tiny quantum ripples should have been present in the very early universe?

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

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