Question 1

The night sky is dark because the universe is neither static nor infinitely old.

Accepted Answer

The darkness of the night sky, known as Olbers' Paradox, is explained by the fact that the universe is expanding and has a finite age, meaning not all light has reached us yet.

Question 2

One explanation of the dark sky Olber's Paradox is that light can reach us only from objects in space out to a distance in light years _______ the age of the universe in years..

Accepted Answer

The answer of One explanation of the dark sky Olber's...

Question 3

Homogeneity is the assumption that the universe looks the same in all directions.

Accepted Answer

The assumption that the universe looks the same in all directions is called isotropy, not homogeneity. Homogeneity refers to the universe having a uniform composition and structure on a large scale.

Question 4

How old is the universe since the Big Bang? Pick the best answer according to radioactive dating in the solar system,light travel times to most distant galaxies,time reversal of the Big Bang,and observations of the 3 degree K radiation.

Accepted Answer

The universe is approximately 14 billion years old, as determined by various methods including radioactive dating, light travel times, and cosmic microwave background radiation observations.

Question 5

What is the fate of an open universe?

Accepted Answer

An open universe will continue to expand forever because it does not have enough mass to stop the expansion.

Question 6

Where did the cosmic microwave background (CMB)come from?

Accepted Answer

The cosmic microwave background (CMB) originated from photons released during the recombination era, when electrons and protons combined to form neutral hydrogen atoms, allowing photons to travel freely through space. This event occurred about 380,000 years after the Big Bang.

Question 7

What evidence supports an acceleration in the expansion rate of the universe?

Accepted Answer

Type Ia supernovae are used as standard candles to measure cosmic distances. The observation that they are fainter than expected in distant galaxies suggests that the universe's expansion rate is accelerating.

Question 8

What observational evidence supports the fact that our universe is expanding?

Accepted Answer

The increasing redshift of galaxies with increasing distance is evidence of the universe's expansion, as it indicates that galaxies are moving away from us, stretching the light to longer, redder wavelengths.

Question 9

Why is the cosmic microwave background (CMB)so cold if the early universe was so hot?

Accepted Answer

The expansion of the universe has stretched the wavelengths of the CMB photons, redshifting them and lowering their temperature from the hot conditions of the early universe to the cooler temperature observed today.

Question 10

Galaxy seeds around which galaxies,clusters,and walls grew may be

Accepted Answer

Defects in space-time, such as cosmic strings or other topological defects, are theorized to act as seeds for the formation of large-scale structures in the universe.

Question 11

_____ in our Milky Way Galaxy's halo can cause sudden brightening of distant stars by gravitationally lensing the light from those stars.This process causes the distant stars to grow brighter over a period of a few tens of days.

Accepted Answer

MACHOs (Massive Compact Halo Objects) in the Milky Way's halo can cause gravitational lensing, leading to the temporary brightening of distant stars.

Question 12

Baryonic matter includes

Accepted Answer

The answer of Baryonic matter includes 
...

Question 13

If the universe is closed,then its age will be

Accepted Answer

The answer of If the universe is closed,then its age...

Question 14

Evidence for a very early "super rapid" inflation of the universe is that the 3° K radiation from opposite sides of the skyand (180 degrees about 28 billion light years apart)is of nearly ________ intensity.This distance is ________ the age of the universe in years.

Accepted Answer

The Cosmic Microwave Background Radiation (CMBR) is nearly uniform in intensity across the sky, suggesting that regions now far apart were once close together, supporting the theory of rapid inflation. The distance is greater than the age of the universe in years, indicating that these regions have moved apart faster than light could travel in the current age of the universe.

Question 15

Astronomers believe that the hydrogen atoms in your body were created ...

Accepted Answer

Hydrogen is the simplest and most common element in the universe, and it was created in the Big Bang, which is the beginning of our universe. Therefore, the hydrogen atoms in our bodies must have been created in the Big Bang.

Question 16

Which of the following is not an assumption of today's cosmology?

Accepted Answer

Geocentrism is not an assumption of today's cosmology. Today's cosmology is based on the assumption that the universe is isotropic and homogeneous, and that the cosmological principle holds.

Question 17

Measurements of the amount of deuterium and the presence of very little lithium-7 in the gas clouds near quasars tell us that

Accepted Answer

The answer of Measurements of the amount of deuterium and...

Question 18

What observation has prompted astronomers to ponder the possible existence of dark energy?

Accepted Answer

Supernovae appearing fainter than expected at large redshifts suggest that the universe's expansion is accelerating, which has led astronomers to hypothesize the existence of dark energy.

Question 19

A frame of the HST deep field image of distant galaxies is shown.By means of optical and radio telescopes astronomers can see distant objects like these as they ...

Accepted Answer

The answer of A frame of the HST deep field...

Question 20

The flatness problem and horizon problem

Accepted Answer

The flatness problem and horizon problem are both resolved by the theory of cosmic inflation, which proposes a rapid expansion of the universe at a very early time, smoothing out any irregularities and explaining the uniformity of the cosmic microwave background.

Quiz 18: Modern Cosmology

The night sky is dark because the universe is neither static nor infinitely old.

One explanation of the dark sky Olber's Paradox is that light can reach us only from objects in space out to a distance in light years _______ the age of the universe in years..

Homogeneity is the assumption that the universe looks the same in all directions.

How old is the universe since the Big Bang? Pick the best answer according to radioactive dating in the solar system,light travel times to most distant galaxies,time reversal of the Big Bang,and observations of the 3 degree K radiation.

What is the fate of an open universe?

Where did the cosmic microwave background (CMB) come from?

What evidence supports an acceleration in the expansion rate of the universe?

What observational evidence supports the fact that our universe is expanding?

Why is the cosmic microwave background (CMB) so cold if the early universe was so hot?

Galaxy seeds around which galaxies,clusters,and walls grew may be

_____ in our Milky Way Galaxy's halo can cause sudden brightening of distant stars by gravitationally lensing the light from those stars.This process causes the distant stars to grow brighter over a period of a few tens of days.

Baryonic matter includes

If the universe is closed,then its age will be

Evidence for a very early "super rapid" inflation of the universe is that the 3° K radiation from opposite sides of the skyand (180 degrees about 28 billion light years apart) is of nearly intensity.This distance is the age of the universe in years.

Astronomers believe that the hydrogen atoms in your body were created ...

Which of the following is not an assumption of today's cosmology?

Measurements of the amount of deuterium and the presence of very little lithium-7 in the gas clouds near quasars tell us that

What observation has prompted astronomers to ponder the possible existence of dark energy?

A frame of the HST deep field image of distant galaxies is shown.By means of optical and radio telescopes astronomers can see distant objects like these as they ...

The flatness problem and horizon problem

Quiz 18: Modern Cosmology

The night sky is dark because the universe is neither static nor infinitely old.

One explanation of the dark sky Olber's Paradox is that light can reach us only from objects in space out to a distance in light years _______ the age of the universe in years..

Homogeneity is the assumption that the universe looks the same in all directions.

How old is the universe since the Big Bang? Pick the best answer according to radioactive dating in the solar system,light travel times to most distant galaxies,time reversal of the Big Bang,and observations of the 3 degree K radiation.

What is the fate of an open universe?

Where did the cosmic microwave background (CMB) come from?

What evidence supports an acceleration in the expansion rate of the universe?

What observational evidence supports the fact that our universe is expanding?

Why is the cosmic microwave background (CMB) so cold if the early universe was so hot?

Galaxy seeds around which galaxies,clusters,and walls grew may be

_____ in our Milky Way Galaxy's halo can cause sudden brightening of distant stars by gravitationally lensing the light from those stars.This process causes the distant stars to grow brighter over a period of a few tens of days.

Baryonic matter includes

If the universe is closed,then its age will be

Evidence for a very early "super rapid" inflation of the universe is that the 3° K radiation from opposite sides of the skyand (180 degrees about 28 billion light years apart) is of nearly ________ intensity.This distance is ________ the age of the universe in years.

Astronomers believe that the hydrogen atoms in your body were created ...

Which of the following is not an assumption of today's cosmology?

Measurements of the amount of deuterium and the presence of very little lithium-7 in the gas clouds near quasars tell us that

What observation has prompted astronomers to ponder the possible existence of dark energy?

A frame of the HST deep field image of distant galaxies is shown.By means of optical and radio telescopes astronomers can see distant objects like these as they ...

The flatness problem and horizon problem

Evidence for a very early "super rapid" inflation of the universe is that the 3° K radiation from opposite sides of the skyand (180 degrees about 28 billion light years apart) is of nearly intensity.This distance is the age of the universe in years.