Question 1

Grand unified theories are very attractive because they can explain:

Accepted Answer

A)  why we have five fundamental forces in the universe today 
B)  why the Big Bang never made any antimatter 
C)  why the universe consists mostly of matter 
D)  why the CMB is very smooth 
E)  what happens inside a black hole 
A)  why we have five fundamental forces in the universe today 
B)  why the Big Bang never made any antimatter 
C)  why the universe consists mostly of matter 
D)  why the CMB is very smooth 
E)  what happens inside a black hole C

Question 2

Which was a triumph of quantum electrodynamics (QED)?

Accepted Answer

A)  QED predicted the existence of three carrier particles before they were discovered in laboratory experiments. 
B)  QED unites the strong and weak nuclear forces. 
C)  QED is an example of a theory of everything. 
D)  QED successfully explains the origin of quantum mechanical fluctuations in the CBR. 
E)  QED combined the electric and magnetic forces. 
A)  QED predicted the existence of three carrier particles before they were discovered in laboratory experiments. 
B)  QED unites the strong and weak nuclear forces. 
C)  QED is an example of a theory of everything. 
D)  QED successfully explains the origin of quantum mechanical fluctuations in the CBR. 
E)  QED combined the electric and magnetic forces. A

Question 3

Figure 2
-Figure 2 shows a graph of the value of  $\Omega$mass as a function of time in a universe with no dark energy. The five different curves correspond to universes with slightly different values for  $\Omega$mass one second after the Big Bang. Which line corresponds to a universe with the largest value of  $\Omega$mass one second after the Big Bang?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  D 
E)  E 
A)  A 
B)  B 
C)  C 
D)  D 
E)  E A

Question 4

The standard model of particle physics is incomplete because it leaves which question(s) unanswered?

Accepted Answer

A)  Why do neutrinos have mass? 
B)  Why is the strong nuclear force much stronger than the weak nuclear force? 
C)  How is gravity related to the other three fundamental forces? 
D)  How does gravity work over such long distances? 
E)  all of the above 
A)  Why do neutrinos have mass? 
B)  Why is the strong nuclear force much stronger than the weak nuclear force? 
C)  How is gravity related to the other three fundamental forces? 
D)  How does gravity work over such long distances? 
E)  all of the above

Question 5

Why does the sum of $\Omega$ mass and $\Omega$$\wedge$  determine the shape of our universe?

Accepted Answer

The mass and energy density af

Question 6

Dark energy is a force that continually decreases the expansion rate of the universe.

Accepted Answer

A) True 
 B)False

Question 7

Why would it be very improbable for our universe to have  $\Omega$mass +$\Omega$$\wedge$  = 0.9?

Accepted Answer

A)  It would quickly evolve to have a much different value of  $\Omega$mass +$\Omega$$\wedge$ . 
B)  In order to exist, every universe must have  $\Omega$mass +  $\Omega$$\wedge$  = 1. 
C)  We know  $\Omega$mass = 1, based on the average density of galaxies. 
D)  The fluctuation in the CMB tell us that  $\Omega$mass +$\Omega$$\wedge$  = 0.7. 
E)  Dark energy studies tell us  $\Omega$$\wedge$  = 0.9. 
A)  It would quickly evolve to have a much different value of  $\Omega$mass +$\Omega$$\wedge$ . 
B)  In order to exist, every universe must have  $\Omega$mass +  $\Omega$$\wedge$  = 1. 
C)  We know  $\Omega$mass = 1, based on the average density of galaxies. 
D)  The fluctuation in the CMB tell us that  $\Omega$mass +$\Omega$$\wedge$  = 0.7. 
E)  Dark energy studies tell us  $\Omega$$\wedge$  = 0.9.

Question 8

Describe the four fundamental forces of nature by listing their names and describing what effect each force has on objects in the universe.

Accepted Answer

The four fundamental forces of nature ar

Question 9

Put the following types of objects in order, starting with the first one to form after the Big Bang and ending with the last one to form:

Accepted Answer

A)  neutral atoms, protons, nuclei 
B)  protons, nuclei, neutral atoms 
C)  nuclei, neutral atoms, protons 
D)  protons, neutral atoms, nuclei 
E)  nuclei, protons, neutral atoms 
A)  neutral atoms, protons, nuclei 
B)  protons, nuclei, neutral atoms 
C)  nuclei, neutral atoms, protons 
D)  protons, neutral atoms, nuclei 
E)  nuclei, protons, neutral atoms

Question 10

Which of the following is FALSE?

Accepted Answer

A)  When the universe was young, matter worked to slow the expansion rate of the universe. 
B)  The Big Bang occurred approximately 13.7 billion years ago. 
C)  Only in the last 5 to 6 billion years has dark energy caused the universe's expansion rate to increase over time. 
D)  Throughout the age of the universe, dark energy has caused its expansion rate to increase over time. 
E)  Astrophysicists are unsure whether or not dark energy always will continue to increase the expansion rate of the universe. 
A)  When the universe was young, matter worked to slow the expansion rate of the universe. 
B)  The Big Bang occurred approximately 13.7 billion years ago. 
C)  Only in the last 5 to 6 billion years has dark energy caused the universe's expansion rate to increase over time. 
D)  Throughout the age of the universe, dark energy has caused its expansion rate to increase over time. 
E)  Astrophysicists are unsure whether or not dark energy always will continue to increase the expansion rate of the universe.

Question 11

Figure 1
-Figure 1 shows five possible graphs of the scale factor of the universe as a function of time. Which of these graphs represent our universe where  $\Omega$ mass = 0.3 and  $\Omega$ $\wedge$ =0.7?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  D 
E)  E 
A)  A 
B)  B 
C)  C 
D)  D 
E)  E

Question 12

Quantum chromodynamics describes how __________ works.

Accepted Answer

A)  gravity 
B)  the strong nuclear force 
C)  electricity 
D)  magnetism 
E)  light 
A)  gravity 
B)  the strong nuclear force 
C)  electricity 
D)  magnetism 
E)  light

Question 13

Which of these are possible types of multiple universes that could exist?

Accepted Answer

A)  parallel universes with different physics and different mathematical explanations 
B)  other parts of an infinite universe which are so far away that we cannot observe them 
C)  quantum mechanical parallel universes, which are created each time something happens that has a probability of occurring in a different way, such as a dice roll 
D)  a multiverse with constant inflation, where each universe forms due to quantum fluctuations stopping that inflation 
E)  all of the above 
A)  parallel universes with different physics and different mathematical explanations 
B)  other parts of an infinite universe which are so far away that we cannot observe them 
C)  quantum mechanical parallel universes, which are created each time something happens that has a probability of occurring in a different way, such as a dice roll 
D)  a multiverse with constant inflation, where each universe forms due to quantum fluctuations stopping that inflation 
E)  all of the above

Question 14

In order to produce an electron and a positron, two photons must have a combined energy of:

Accepted Answer

A)  E $\gt$ 2mec2 
B)  E $\gt$ mec2 
C)  E $\gt$ 1/2mec2 
D)  E = mec2 
E)  This cannot happen. 
A)  E $\gt$ 2mec2 
B)  E $\gt$ mec2 
C)  E $\gt$ 1/2mec2 
D)  E = mec2 
E)  This cannot happen.

Question 15

What is the Planck era?

Accepted Answer

A)  the earliest moments after the Big Bang 
B)  a period when quantum mechanics is needed to describe spacetime in addition to particles 
C)  the time period when a theory of everything (TO
E)  is needed to understand the universe 
D)  When spacetime can be described as a quantum mechanical "foam" rather than a smooth sheet 
E)  all of the above 
A)  the earliest moments after the Big Bang 
B)  a period when quantum mechanics is needed to describe spacetime in addition to particles 
C)  the time period when a theory of everything (TO
E)  is needed to understand the universe 
D)  When spacetime can be described as a quantum mechanical "foam" rather than a smooth sheet 
E)  all of the above

Question 16

If the sum of the mass and energy density in the universe yields $\Omega$ $\lt$ 1, then the universe will recollapse in a Big Crunch.

Accepted Answer

A) True 
 B)False

Question 17

What do astronomers believe is currently having the largest effect on the change in the expansion rate of the present-day universe?

Accepted Answer

A)  dark matter 
B)  baryonic (normal) matter 
C)  dark energy 
D)  radiation pressure 
E)  gravity 
A)  dark matter 
B)  baryonic (normal) matter 
C)  dark energy 
D)  radiation pressure 
E)  gravity

Question 18

What was the temperature of the universe when a typical CMB photon was no longer able to spontaneously create a proton and antiproton pair? Note that a photon has an energy equal to E = hc/$\lambda$, the CBR at any point in time has a blackbody spectrum that peaks at $\lambda$peak = (2,900 $\mu$m K)/T, and the mass of a single proton is 1.7 *10-27 kg.

Accepted Answer

In order to create a proton and antiprot

Question 19

The force that binds three quarks together to make up a proton or neutron is called the weak force.

Accepted Answer

A) True 
 B)False

Question 20

Why is the fact that the cosmic microwave background radiation (CMB) is very smooth considered a problem?

Accepted Answer

A)  A universe as smooth as predicted by the CMB should not have formed as many galaxies as have been observed. 
B)  A universe as smooth as predicted by the CMB should have collapsed by now. 
C)  A universe as smooth as predicted by the CMB should be expanding much faster than we are now. 
D)  A universe as smooth as predicted by the CMB should never occur because quantum mechanical fluctuations would have been imprinted on it. 
E)  A universe as smooth as predicted by the CMB should never have formed any stars or galaxies. 
A)  A universe as smooth as predicted by the CMB should not have formed as many galaxies as have been observed. 
B)  A universe as smooth as predicted by the CMB should have collapsed by now. 
C)  A universe as smooth as predicted by the CMB should be expanding much faster than we are now. 
D)  A universe as smooth as predicted by the CMB should never occur because quantum mechanical fluctuations would have been imprinted on it. 
E)  A universe as smooth as predicted by the CMB should never have formed any stars or galaxies.

Exam 22: Modern Cosmology

Grand unified theories are very attractive because they can explain:

Which was a triumph of quantum electrodynamics (QED)?

The standard model of particle physics is incomplete because it leaves which question(s) unanswered?

Why does the sum of Ω\OmegaΩ mass and Ω\OmegaΩ ∧\wedge∧ determine the shape of our universe?

Dark energy is a force that continually decreases the expansion rate of the universe.

Why would it be very improbable for our universe to have Ω\OmegaΩ mass + Ω\OmegaΩ ∧\wedge∧ = 0.9?

Describe the four fundamental forces of nature by listing their names and describing what effect each force has on objects in the universe.

Put the following types of objects in order, starting with the first one to form after the Big Bang and ending with the last one to form:

Which of the following is FALSE?

Figure 1 -Figure 1 shows five possible graphs of the scale factor of the universe as a function of time. Which of these graphs represent our universe where Ω\OmegaΩ mass = 0.3 and Ω\OmegaΩ ∧\wedge∧ =0.7?

Quantum chromodynamics describes how __________ works.

Which of these are possible types of multiple universes that could exist?

In order to produce an electron and a positron, two photons must have a combined energy of:

What is the Planck era?

If the sum of the mass and energy density in the universe yields Ω\OmegaΩ <\lt< 1, then the universe will recollapse in a Big Crunch.

What do astronomers believe is currently having the largest effect on the change in the expansion rate of the present-day universe?

The force that binds three quarks together to make up a proton or neutron is called the weak force.

Why is the fact that the cosmic microwave background radiation (CMB) is very smooth considered a problem?

Why Learn Astronomy

Patterns in the Skymotions of Earth

Motion of Astronomical Bodies

Gravity and Orbits

Light

The Tools of the Astronomer

The Birth and Evolution of Planetary Systems

The Terrestrial Planets and Earths Moon

Atmospheres of the Terrestrial Planets

Worlds of Gas and Liquid the Giant Planets

Planetary Adornmentsmoons and Rings

Dwarf Planets and Small Solar System Bodies

Taking the Measure of Stars

Our Starthe Sun

Star Formation and the Interstellar Medium

Evolution of Low-Mass Stars

Evolution of High-Mass Stars

Relativity and Black Holes

The Expanding Universe

Galaxies

The Milky Waya Normal Spiral Galaxy

Large-Scale Structure in the Universe

Life

Filters

Why does the sum of $\Omega$ _mass and $\Omega$ _$\wedge$ determine the shape of our universe?

Why would it be very improbable for our universe to have $\Omega$ _mass + $\Omega$ _$\wedge$ = 0.9?

If the sum of the mass and energy density in the universe yields $\Omega$ $\lt$ 1, then the universe will recollapse in a Big Crunch.