Question 1

The universe can be infinite in size for which shapes of the universe?

Accepted Answer

A)  Open 
B)  Closed 
C)  Flat 
D)  Open and flat 
A)  Open 
B)  Closed 
C)  Flat 
D)  Open and flat D

Question 2

To determine how the expansion rate of the universe has changed over time,astronomers must measure __________ for a sample of Type I supernovae in distant galaxies.

Accepted Answer

A)  redshift and luminosity 
B)  redshift and brightness 
C)  distance and luminosity 
D)  distance and brightness 
A)  redshift and luminosity 
B)  redshift and brightness 
C)  distance and luminosity 
D)  distance and brightness B

Question 3

Grand unified theories are very attractive because they can explain

Accepted Answer

A)  why the universe consists mostly of matter. 
B)  why the Big Bang never made any antimatter. 
C)  why we have five fundamental forces in the universe today. 
D)  why the CBR is very smooth. 
A)  why the universe consists mostly of matter. 
B)  why the Big Bang never made any antimatter. 
C)  why we have five fundamental forces in the universe today. 
D)  why the CBR is very smooth. A

Question 4

According to superstring theory,how are different varieties of elementary particles similar? How do they differ?

Accepted Answer

In superstring theory,all elem

Question 5

If the sum of the mass and energy density in the universe yields   then the universe will recollapse in a Big Crunch.

Accepted Answer

A) True 
 B)False

Question 6

Is Einstein's "biggest blunder" still considered a mistake?

Accepted Answer

A)  No,the cosmological constant is nonzero. 
B)  Yes,the cosmological constant turned out to be zero. 
C)  Somewhat,because he could have predicted that the universe was expanding even before Hubble observed it. 
D)  Both a and c are correct. 
A)  No,the cosmological constant is nonzero. 
B)  Yes,the cosmological constant turned out to be zero. 
C)  Somewhat,because he could have predicted that the universe was expanding even before Hubble observed it. 
D)  Both a and c are correct.

Question 7

Inflation happened

Accepted Answer

A)  when the universe was   s old. 
B)  when the universe expanded by a factor of approximately   . 
C)  when the average energy of the vacuum of spacetime changed. 
D)  All of the above 
A)  when the universe was   s old. 
B)  when the universe expanded by a factor of approximately   . 
C)  when the average energy of the vacuum of spacetime changed. 
D)  All of the above

Question 8

What is the name of the particle that mediates the electromagnetic force in quantum electrodynamics (QED)and the strong force in quantum chromodynamics (QCD)?

Accepted Answer

The photon is the particle tha

Question 9

The three fundamental forces of nature are gravity,electromagnetism,and the strong force.

Accepted Answer

A) True 
 B)False

Question 10

As the universe cooled shortly after the Big Bang,which was the first fundamental force to separate itself out from the others?

Accepted Answer

A)  Electromagnetism 
B)  Gravity 
C)  The strong force 
D)  The weak force 
A)  Electromagnetism 
B)  Gravity 
C)  The strong force 
D)  The weak force

Question 11

Astronomers have confirmed the grand unified theory by observing that protons decay in laboratory experiments.

Accepted Answer

A) True 
 B)False

Question 12

If you found a globular cluster that had an age of 20 billion years,what cosmological observations would conflict with this observation?

Accepted Answer

The WMAP results on the CBR sa

Question 13

In the 1990s,astronomers found that distant Type I supernova were __________ than they expected,leading them to conclude that __________.

Accepted Answer

A)  brighter;the universe's expansion rate was decreasing with time 
B)  brighter;the universe was finite in size 
C)  fainter;the universe's expansion rate has been increasing with time 
D)  fainter;the universe was infinite in size 
A)  brighter;the universe's expansion rate was decreasing with time 
B)  brighter;the universe was finite in size 
C)  fainter;the universe's expansion rate has been increasing with time 
D)  fainter;the universe was infinite in size

Question 14

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

Accepted Answer

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

Question 15

What are two observations that when combined tell us that the universe has   and is flat?

Accepted Answer

Correct answers are any two pa

Question 16

The weak force mediates the beta decay of neutrons into protons,electrons,and antineutrinos.

Accepted Answer

A) True 
 B)False

Question 17

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)  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)  All of the above

Question 18

What was the temperature of the universe when a typical CBR photon was no longer able to spontaneously create an electron and positron pair? Note that a photon has an energy equal to   the CBR at any point in time has a blackbody spectrum that peaks at   ,and the mass of a single electron is   .

Accepted Answer

A)  2,000 K 
B)  400,000 K 
C)  4 million K 
D)  2 billion K 
A)  2,000 K 
B)  400,000 K 
C)  4 million K 
D)  2 billion K

Question 19

In a closed (spherical)universe,the sum of the angles in a triangle is

Accepted Answer

A)  180 degrees. 
B)   180 degrees. 
D)  240 degrees. 
A)  180 degrees. 
B)   180 degrees. 
D)  240 degrees.

Question 20

What would the universe be like if there were complete symmetry between matter and antimatter?

Accepted Answer

A)  It would look similar to our universe,but half of it would be composed of antimatter. 
B)  We would observe two universes,one an antimatter reflection of the other. 
C)  There would be no universe,because all of the matter and antimatter would have been annihilated. 
D)  There would be a universe,but it would be completely composed of energy. 
A)  It would look similar to our universe,but half of it would be composed of antimatter. 
B)  We would observe two universes,one an antimatter reflection of the other. 
C)  There would be no universe,because all of the matter and antimatter would have been annihilated. 
D)  There would be a universe,but it would be completely composed of energy.

Exam 21: Modern Cosmology

The universe can be infinite in size for which shapes of the universe?

To determine how the expansion rate of the universe has changed over time,astronomers must measure __________ for a sample of Type I supernovae in distant galaxies.

Grand unified theories are very attractive because they can explain

According to superstring theory,how are different varieties of elementary particles similar? How do they differ?

If the sum of the mass and energy density in the universe yields then the universe will recollapse in a Big Crunch.

Is Einstein's "biggest blunder" still considered a mistake?

Inflation happened

What is the name of the particle that mediates the electromagnetic force in quantum electrodynamics (QED)and the strong force in quantum chromodynamics (QCD)?

The three fundamental forces of nature are gravity,electromagnetism,and the strong force.

As the universe cooled shortly after the Big Bang,which was the first fundamental force to separate itself out from the others?

Astronomers have confirmed the grand unified theory by observing that protons decay in laboratory experiments.

If you found a globular cluster that had an age of 20 billion years,what cosmological observations would conflict with this observation?

In the 1990s,astronomers found that distant Type I supernova were __________ than they expected,leading them to conclude that __________.

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

What are two observations that when combined tell us that the universe has and is flat?

The weak force mediates the beta decay of neutrons into protons,electrons,and antineutrinos.

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

What was the temperature of the universe when a typical CBR photon was no longer able to spontaneously create an electron and positron pair? Note that a photon has an energy equal to the CBR at any point in time has a blackbody spectrum that peaks at ,and the mass of a single electron is .

In a closed (spherical)universe,the sum of the angles in a triangle is

What would the universe be like if there were complete symmetry between matter and antimatter?

Why Learn Astronomy

Patterns in the Skymotions of Earth

Gravity and Orbitsa Celestial Ballet

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 Liquidthe Giant Planets

Gravity Is More Than Keplers Laws

Planetary Adornmentsmoons and Rings

Dwarf Planets and Small Solar System Bodies

Taking the Measure of Stars

A Run-Of-The-Mill G-Type Starour Sun

Star Formation and the Interstellar Medium

Stars in the Slow Lanelow-Mass Stellar Evolution

Live Fast,die Younghigh-Mass Stellar Evolution

Our Expanding Universe

Galaxies

The Milky Waya Normal Spiral Galaxy

The Origin of Structure

Life

Filters

In the 1990s,astronomers found that distant Type I supernova were than they expected,leading them to conclude that .