Question 1

To verify whether some grand unified theories are correct, physicists are searching for

Accepted Answer

A)  the Big Rip. 
B)  mini-black holes. 
C)  antimatter. 
D)  protons that decay. 
E)  dark matter that decays. 
A)  the Big Rip. 
B)  mini-black holes. 
C)  antimatter. 
D)  protons that decay. 
E)  dark matter that decays.

Question 2

As a result of our universe undergoing an accelerated expansion,

Accepted Answer

A)  ( $\Omega$$\bigwedge$  must be exactly zero.) 
B)  the fate of the universe is exclusively dictated by ( $\Omega$m.) 
C)  the mass density must be larger than the critical density. 
D)  the only possible outcome is the Big Crunch. 
E)  the age of the universe is currently greater than the Hubble time. 
A)  ( $\Omega$$\bigwedge$  must be exactly zero.) 
B)  the fate of the universe is exclusively dictated by ( $\Omega$m.) 
C)  the mass density must be larger than the critical density. 
D)  the only possible outcome is the Big Crunch. 
E)  the age of the universe is currently greater than the Hubble time.

Question 3

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

Accepted Answer

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

Question 4

What is needed for a "Big Rip" scenario? How does this compare with our universe?

Accepted Answer

For a "Big Rip" scenario to occur,dark e

Question 5

Observations of Type Ia supernovae show that the redshifts of the most distant galaxies are ________ the value predicted by Hubble's Law.

Accepted Answer

A)  the same as 
B)  less than 
C)  greater than 
D)  the reciprocal of 
E)  negative 
A)  the same as 
B)  less than 
C)  greater than 
D)  the reciprocal of 
E)  negative

Question 6

The large-scale effects of dark energy are summarized through the

Accepted Answer

A)  local expansion rate, $\Omega$. 
B)  cosmological constant,$\bigwedge$. 
C)  Hubble constant, H0. 
D)  amount of matter in the universe, $\Omega$m. 
E)  critical density, $\Omega$0. 
A)  local expansion rate, $\Omega$. 
B)  cosmological constant,$\bigwedge$. 
C)  Hubble constant, H0. 
D)  amount of matter in the universe, $\Omega$m. 
E)  critical density, $\Omega$0.

Question 7

Explain, ignoring dark energy, how the figure below describes three different scenarios for the evolution of the universe.Be sure to explain the meaning of the scale factor, RU.

Accepted Answer

This plot shows three possible scenarios

Question 8

Mass density acts to ________ the expansion of the universe, and dark energy acts to ________ the expansion.

Accepted Answer

A)  slow down; slow down 
B)  slow down; speed up 
C)  speed up; slow down 
D)  speed up; speed up 
E)  slow down; stabilize 
A)  slow down; slow down 
B)  slow down; speed up 
C)  speed up; slow down 
D)  speed up; speed up 
E)  slow down; stabilize

Question 9

Select the true statement:

Accepted Answer

A)  ( $\Omega$$\bigwedge$  makes the universe flatter, while  $\Omega$m makes the universe less flat.) 
B)  ( $\Omega$$\bigwedge$  + $\Omega$m is much smaller than the critical density.) 
C)  ( $\Omega$m is very close to zero.) 
D)  ( $\Omega$$\bigwedge$  and  $\Omega$m both affect the predictions about the fate and age of the universe.) 
E)  Current observational data seem to suggest that the universe is not flat. 
A)  ( $\Omega$$\bigwedge$  makes the universe flatter, while  $\Omega$m makes the universe less flat.) 
B)  ( $\Omega$$\bigwedge$  + $\Omega$m is much smaller than the critical density.) 
C)  ( $\Omega$m is very close to zero.) 
D)  ( $\Omega$$\bigwedge$  and  $\Omega$m both affect the predictions about the fate and age of the universe.) 
E)  Current observational data seem to suggest that the universe is not flat.

Question 10

In modern cosmology, Einstein's cosmological constant is

Accepted Answer

A)  an example of dark energy that causes an accelerated expansion of the universe. 
B)  vanishingly zero. 
C)  another name for the critical density of the universe. 
D)  the only explanation for an infinite universe. 
E)  of no use, as it predicts a static universe. 
A)  an example of dark energy that causes an accelerated expansion of the universe. 
B)  vanishingly zero. 
C)  another name for the critical density of the universe. 
D)  the only explanation for an infinite universe. 
E)  of no use, as it predicts a static universe.

Question 11

Explain why the superstring theory is considered more like a speculative idea or hypothesis than a scientific theory.

Accepted Answer

The superstring "theory" has emerged as

Question 12

The critical mass density of the universe today is 9.5 *10 - 27 kg/m3.Using (only) the currently observed amount of luminous matter, what would be the average mass density in the universe? If protons were spread evenly throughout the universe, what would be their typical separation? (Note that the typical separation between protons would be roughly equal to the cubic root of the average volume occupied by one proton, and the mass of a proton is 1.67 *10 - 27 kg.)

Accepted Answer

Based on the estimated amount of luminou

Question 13

Which of the following has the greatest effect on the expansion rate of today's universe?

Accepted Answer

A)  dark matter 
B)  luminous matter 
C)  dark energy 
D)  radiation pressure 
E)  nuclear decays 
A)  dark matter 
B)  luminous matter 
C)  dark energy 
D)  radiation pressure 
E)  nuclear decays

Question 14

The concept behind the possible existence of multiverses is that

Accepted Answer

A)  if the universe has infinite space dimensions, then many nearly identical universes may be "stacked" in the dimensions that we cannot currently perceive. 
B)  if the cosmological principle does not hold at very large distances, then far outside our visible universe you might find places with laws of physics very different from our own. 
C)  if string theory is correct, then each "extra" dimension may actually be an entire separate universe. 
D)  fluctuations in the cosmic microwave background imply that some pockets of space should have different laws of physics than others. 
E)  there is no reasoning behind multiverses; they are a product of science fiction. 
A)  if the universe has infinite space dimensions, then many nearly identical universes may be "stacked" in the dimensions that we cannot currently perceive. 
B)  if the cosmological principle does not hold at very large distances, then far outside our visible universe you might find places with laws of physics very different from our own. 
C)  if string theory is correct, then each "extra" dimension may actually be an entire separate universe. 
D)  fluctuations in the cosmic microwave background imply that some pockets of space should have different laws of physics than others. 
E)  there is no reasoning behind multiverses; they are a product of science fiction.

Question 15

Superstring theory is a candidate for a(n)

Accepted Answer

A)  infinite number of multiverses. 
B)  theory of everything. 
C)  theory describing the era prior to the Big Bang. 
D)  more fundamental theory of gravity, but ignores the other forces. 
E)  way to violate the cosmological principle. 
A)  infinite number of multiverses. 
B)  theory of everything. 
C)  theory describing the era prior to the Big Bang. 
D)  more fundamental theory of gravity, but ignores the other forces. 
E)  way to violate the cosmological principle.

Question 16

At what stage in the universe's history do we think the asymmetry between matter and antimatter was created?

Accepted Answer

A)  at the very moment the Big Bang occurred 
B)  around the time gravity separated from the single superforce 
C)  around the time the strong force separated from the grand unified theory 
D)  around the time the weak force and electromagnetism separated 
E)  around the time the electric and magnetic forces separated 
A)  at the very moment the Big Bang occurred 
B)  around the time gravity separated from the single superforce 
C)  around the time the strong force separated from the grand unified theory 
D)  around the time the weak force and electromagnetism separated 
E)  around the time the electric and magnetic forces separated

Question 17

The accelerated expansion of the universe was observationally discovered using

Accepted Answer

A)  Type Ia supernovae. 
B)  Cepheid variables. 
C)  RR Lyrae. 
D)  stellar parallax. 
E)  colors of galaxies. 
A)  Type Ia supernovae. 
B)  Cepheid variables. 
C)  RR Lyrae. 
D)  stellar parallax. 
E)  colors of galaxies.

Question 18

List the four fundamental forces of nature and describe what effect each force has on objects in the universe.

Accepted Answer

The four fundamental forces of nature ar

Question 19

If  $\Omega$m + $\Omega$$\bigwedge$  =1 today and dark energy were a cosmological constant, the universe would

Accepted Answer

A)  expand forever. 
B)  slow its expansion but never reverse it. 
C)  stop expanding and eventually collapse. 
D)  oscillate between expansion and collapse. 
E)  expand so quickly that it is ripped apart. 
A)  expand forever. 
B)  slow its expansion but never reverse it. 
C)  stop expanding and eventually collapse. 
D)  oscillate between expansion and collapse. 
E)  expand so quickly that it is ripped apart.

Question 20

Why does the sum of  $\Omega$m and  $\Omega$ $\bigwedge$  determine the shape of our universe?

Accepted Answer

The mass and energy density summed toget

Exam 22: Cosmology

To verify whether some grand unified theories are correct, physicists are searching for

As a result of our universe undergoing an accelerated expansion,

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

What is needed for a "Big Rip" scenario? How does this compare with our universe?

Observations of Type Ia supernovae show that the redshifts of the most distant galaxies are ________ the value predicted by Hubble's Law.

The large-scale effects of dark energy are summarized through the

Explain, ignoring dark energy, how the figure below describes three different scenarios for the evolution of the universe.Be sure to explain the meaning of the scale factor, RU.

Mass density acts to ________ the expansion of the universe, and dark energy acts to ________ the expansion.

Select the true statement:

In modern cosmology, Einstein's cosmological constant is

Explain why the superstring theory is considered more like a speculative idea or hypothesis than a scientific theory.

Which of the following has the greatest effect on the expansion rate of today's universe?

The concept behind the possible existence of multiverses is that

Superstring theory is a candidate for a(n)

At what stage in the universe's history do we think the asymmetry between matter and antimatter was created?

The accelerated expansion of the universe was observationally discovered using

List the four fundamental forces of nature and describe what effect each force has on objects in the universe.

If Ω\OmegaΩ m + Ω\OmegaΩ ⋀\bigwedge⋀ =1 today and dark energy were a cosmological constant, the universe would

Why does the sum of Ω\OmegaΩ m and Ω\OmegaΩ ⋀\bigwedge⋀ determine the shape of our universe?

Thinking Like an Astronomer

Patterns in the Skymotions of Earth and the Moon

Motion of Astronomical Bodies

Gravity and Orbits

Light

The Tools of the Astronomer

The Formation of Planetary Systems

The Terrestrial Planets and Earths Moon

Atmospheres of the Terrestrial Planets

Worlds of Gas and Liquidthe Giant Planets

Planetary Moons and Rings

Dwarf Planets and Small Solar System Bodies

Taking the Measure of Stars

Our Starthe Sun

The Interstellar Medium and Star Formation

Evolution of Low-Mass Stars

Evolution of High-Mass Stars

Relativity and Black Holes

Galaxies

The Milky Waya Normal Spiral Galaxy

The Expanding Universe

Large-Scale Structure in the Universe

Life

Filters

Explain, ignoring dark energy, how the figure below describes three different scenarios for the evolution of the universe.Be sure to explain the meaning of the scale factor, R_U.

Mass density acts to the expansion of the universe, and dark energy acts to the expansion.

If $\Omega$ _m + $\Omega$ _$\bigwedge$ =1 today and dark energy were a cosmological constant, the universe would

Why does the sum of $\Omega$ _m and $\Omega$ _$\bigwedge$ determine the shape of our universe?