Question 1

If the distance of a galaxy at a redshift z = 0.05 is 220 Mpc, how many years back into the past are we looking when we observe this galaxy?

Accepted Answer

A)   5 million years
B)   220 million years
C)   720 million years
D)   6 billion years
E)   10 billion years

Question 2

If we lived in a galaxy 1 billion light-years from our own, what would we see?

Accepted Answer

A)   a universe 1 billion years younger than ours
B)   a universe 1 billion years older than ours
C)   much the same universe as we see here
D)   a universe expanding at a slower rate than we see from Earth
E)   a universe expanding at a faster rate than we see from Earth

Question 3

If the distance of a galaxy is 5 Mpc, what is its recessional velocity if the Hubble constant is 70 km/s/Mpc?

Accepted Answer

A)   70 km/s
B)   100 km/s
C)   350 km/s
D)   500 km/s
E)   700 km/s

Question 4

It is possible for a galaxy to have an apparent velocity greater than the speed of light.This means that the galaxy

Accepted Answer

A)   has an active nucleus capable of producing relativistic jets.
B)   is approaching us and the measured speed is a mere artifact of projecting its velocity along the line of sight.
C)   has been ejected at tremendous speed by the Big Bang.
D)   is being temporarily accelerated by large numbers of simultaneous supernovae blasts.
E)   is being carried by the expansion of the universe.

Question 5

In the early 1960s, physicists Penzias and Wilson detected a persistent noise at a wavelength of about 1 mm in their radio telescope that came from all directions in the sky due to

Accepted Answer

A)   synchrotron emission from the Crab Nebula.
B)   emission from newly formed stars in the Orion Nebula.
C)   cellphone usage.
D)   photons left over from the Big Bang.
E)   television and radio broadcasting.

Question 6

The existence of the cosmic background radiation tells us that the early universe was

Accepted Answer

A)   much hotter than it is today.
B)   much colder than it is today.
C)   composed entirely of radiation at early times.
D)   composed entirely of stars at early times.
E)   about the same temperature as today but much more dense.

Question 7

The CMB is a snapshot of the radiation in the universe at a redshift of z  1,000 when the universe was about

Accepted Answer

A)   1,000 times smaller than it is today.
B)   10 times smaller than it is today.
C)   2 times smaller than it is today.
D)   the same size as it is today.
E)   10 times larger than it is today.

Question 8

Explain how the figure below shows evidence supporting the Big Bang theory.

Accepted Answer

The Big Bang theory predicts that only c...

Question 9

If you measured the distances and recessional velocities for a sample of galaxies and plotted the data to get the figure shown below, what value would you derive for the Hubble constant?

Accepted Answer

A)   10 km/s/Mpc
B)   50 km/s/Mpc
C)   70 km/s/Mpc
D)   100 km/s/Mpc
E)   500 km/s/Mpc

Question 10

Briefly explain how an accurate determination of Hubble constant has improved our understanding of cosmology.

Accepted Answer

With an accurate determination of the Hu...

Question 11

The oldest photons we detect in the universe come from

Accepted Answer

A)   distant quasars.
B)   the first generations of stars.
C)   the most distant galaxies.
D)   the epoch of recombination.
E)   the first supernovae.

Question 12

If the Hubble constant were equal to 50 km/s/Mpc, what would the approximate age of the universe (the Hubble time) be, assuming that the expansion rate has stayed approximately constant over time? Note that 1 Mpc = 3.086 * 1019 km and 1 year = 3.154 * 107 s.

Accepted Answer

The age of the universe would ...

Question 13

Galaxy peculiar velocities are typically about 300 km/s.How far away do you have to look in order to see recessional velocities that are 10 times this peculiar velocity? Note that the Hubble constant has a value of 70 km/s/Mpc.

Accepted Answer

A)   12 Mpc
B)   25 Mly
C)   37 Mpc
D)   43 Mpc
E)   52 Mpc

Question 14

Why did Big Bang nucleosynthesis only produce elements less massive than beryllium?

Accepted Answer

A)   The laws of physics do not allow the formation of massive nuclei outside stars.
B)   The universe was never hot enough for nucleosynthesis by fusion before stars formed.
C)   There was no black hole to provide sufficient energy for advanced nucleosynthesis.
D)   The universe expanded and cooled rapidly.
E)   More massive elements did form, but they decayed very rapidly into lighter ones.

Question 15

The apparent recessional velocities of galaxies at large distances are due mainly to

Accepted Answer

A)   the actual motions of the galaxies through space.
B)   the motion of our Sun around the galactic center.
C)   a continuously increasing scaling factor of the universe.
D)   the relativistic jets launched by supermassive black holes.
E)   incorrect interpretation of spectra from galaxies.

Question 16

Distant galaxies we can see today with a redshift of z  6 emitted their light when the universe was

Accepted Answer

A)   5 times smaller than it is today.
B)   6 times smaller than it is today.
C)   7 times smaller than it is today.
D)   8 times smaller than it is today.
E)   the same size as it is today.

Question 17

The COBE and WMAP satellites detected fluctuations in the CMB.On average, how big were these fluctuations, and what do they that tell us about the universe at a redshift of z = 1,000?

Accepted Answer

After correcting for the Milky Way's mot...

Question 18

If a scientist in the distant Andromeda Galaxy studies the hydrogen gas in that galaxy, they will measure ________ what a scientist in our galaxy would measure, studying hydrogen gas
In the Milky Way.

Accepted Answer

A)   a larger mass per atom than
B)   a smaller mass per atom than
C)   a different set of spectral lines than
D)   different possible chemical bonds with other elements than
E)   the same properties as

Exam 21: The Expanding Universe

It is possible for a galaxy to have an apparent velocity greater than the speed of light.This means that the galaxy

Correct Answer
verified

If the Hubble constant were equal to 50 km/s/Mpc, what would the approximate age of the universe (the Hubble time) be, assuming that the expansion rate has stayed approximately constant over time? Note that 1 Mpc = 3.086 * 10¹⁹ km and 1 year = 3.154 * 10⁷ s.

Correct Answer
verified
The age of the universe would ...
View Answer

The COBE and WMAP satellites detected fluctuations in the CMB.On average, how big were these fluctuations, and what do they that tell us about the universe at a redshift of z = 1,000?

Correct Answer
verified
After correcting for the Milky Way's mot...
View Answer

Explain how the figure below shows evidence supporting the Big Bang theory.

Correct Answer
verified
The Big Bang theory predicts that only c...
View Answer

If a scientist in the distant Andromeda Galaxy studies the hydrogen gas in that galaxy, they will measure ________ what a scientist in our galaxy would measure, studying hydrogen gas In the Milky Way.

Correct Answer
verified

Galaxy peculiar velocities are typically about 300 km/s.How far away do you have to look in order to see recessional velocities that are 10 times this peculiar velocity? Note that the Hubble constant has a value of 70 km/s/Mpc.

Correct Answer
verified

If you measured the distances and recessional velocities for a sample of galaxies and plotted the data to get the figure shown below, what value would you derive for the Hubble constant?

Correct Answer
verified

Why did Big Bang nucleosynthesis only produce elements less massive than beryllium?

Correct Answer
verified

The apparent recessional velocities of galaxies at large distances are due mainly to

Correct Answer
verified

If the distance of a galaxy is 5 Mpc, what is its recessional velocity if the Hubble constant is 70 km/s/Mpc?

Correct Answer
verified

In the early 1960s, physicists Penzias and Wilson detected a persistent noise at a wavelength of about 1 mm in their radio telescope that came from all directions in the sky due to

Correct Answer
verified

Briefly explain how an accurate determination of Hubble constant has improved our understanding of cosmology.

Correct Answer
verified
With an accurate determination of the Hu...
View Answer

The existence of the cosmic background radiation tells us that the early universe was

Correct Answer
verified

Distant galaxies we can see today with a redshift of z 6 emitted their light when the universe was

Correct Answer
verified

The CMB is a snapshot of the radiation in the universe at a redshift of z 1,000 when the universe was about

Correct Answer
verified

The oldest photons we detect in the universe come from

Correct Answer
verified

If the distance of a galaxy at a redshift z = 0.05 is 220 Mpc, how many years back into the past are we looking when we observe this galaxy?

Correct Answer
verified

If we lived in a galaxy 1 billion light-years from our own, what would we see?

Correct Answer
verified

Exam 21: The Expanding Universe

It is possible for a galaxy to have an apparent velocity greater than the speed of light.This means that the galaxy

Correct AnswerverifiedShow Answer

If the Hubble constant were equal to 50 km/s/Mpc, what would the approximate age of the universe (the Hubble time) be, assuming that the expansion rate has stayed approximately constant over time? Note that 1 Mpc = 3.086 * 1019 km and 1 year = 3.154 * 107 s.

Correct AnswerverifiedThe age of the universe would ...View AnswerShow Answer

The COBE and WMAP satellites detected fluctuations in the CMB.On average, how big were these fluctuations, and what do they that tell us about the universe at a redshift of z = 1,000?

Correct AnswerverifiedAfter correcting for the Milky Way's mot...View AnswerShow Answer

Explain how the figure below shows evidence supporting the Big Bang theory.

Correct AnswerverifiedThe Big Bang theory predicts that only c...View AnswerShow Answer

If a scientist in the distant Andromeda Galaxy studies the hydrogen gas in that galaxy, they will measure ________ what a scientist in our galaxy would measure, studying hydrogen gas In the Milky Way.

Correct AnswerverifiedShow Answer

Galaxy peculiar velocities are typically about 300 km/s.How far away do you have to look in order to see recessional velocities that are 10 times this peculiar velocity? Note that the Hubble constant has a value of 70 km/s/Mpc.

Correct AnswerverifiedShow Answer

If you measured the distances and recessional velocities for a sample of galaxies and plotted the data to get the figure shown below, what value would you derive for the Hubble constant?

Correct AnswerverifiedShow Answer

Why did Big Bang nucleosynthesis only produce elements less massive than beryllium?

Correct AnswerverifiedShow Answer

The apparent recessional velocities of galaxies at large distances are due mainly to

Correct AnswerverifiedShow Answer

If the distance of a galaxy is 5 Mpc, what is its recessional velocity if the Hubble constant is 70 km/s/Mpc?

Correct AnswerverifiedShow Answer

In the early 1960s, physicists Penzias and Wilson detected a persistent noise at a wavelength of about 1 mm in their radio telescope that came from all directions in the sky due to

Correct AnswerverifiedShow Answer

Briefly explain how an accurate determination of Hubble constant has improved our understanding of cosmology.

Correct AnswerverifiedWith an accurate determination of the Hu...View AnswerShow Answer

The existence of the cosmic background radiation tells us that the early universe was

Correct AnswerverifiedShow Answer

Distant galaxies we can see today with a redshift of z 6 emitted their light when the universe was

Correct AnswerverifiedShow Answer

The CMB is a snapshot of the radiation in the universe at a redshift of z 1,000 when the universe was about

Correct AnswerverifiedShow Answer

The oldest photons we detect in the universe come from

Correct AnswerverifiedShow Answer

If the distance of a galaxy at a redshift z = 0.05 is 220 Mpc, how many years back into the past are we looking when we observe this galaxy?

Correct AnswerverifiedShow Answer

If we lived in a galaxy 1 billion light-years from our own, what would we see?

Correct AnswerverifiedShow Answer

Correct Answer
verified

If the Hubble constant were equal to 50 km/s/Mpc, what would the approximate age of the universe (the Hubble time) be, assuming that the expansion rate has stayed approximately constant over time? Note that 1 Mpc = 3.086 * 10¹⁹ km and 1 year = 3.154 * 10⁷ s.

Correct Answer
verified
The age of the universe would ...
View Answer

Correct Answer
verified
After correcting for the Milky Way's mot...
View Answer

Correct Answer
verified
The Big Bang theory predicts that only c...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
With an accurate determination of the Hu...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified