Free Practice Quiz Question List

8 Dark Energy and the Fate of the Universe Online Quiz Questions

Use this free practice quiz with 20 questions to review 8 Dark Energy and the Fate of the Universe, test your knowledge, and prepare for your next test or exam.

20 questions

True or false

1 point

True or false: The universe’s accelerated expansion means that atoms and other gravitationally bound structures generally expand with the universe.

A
True
B
False

Choose one

1 point

Which statement best distinguishes dark matter from dark energy?

A
Dark matter is associated with accelerated expansion, while dark energy helps build cosmic structure.
B
Dark matter attracts gravitationally and helps build cosmic structure, while dark energy is associated with accelerated expansion.
C
Both dark matter and dark energy are names for the same component.
D
Dark energy holds atoms together, while dark matter causes the universe to expand.

Fill in the blank

1 point

In general relativity, cosmic expansion accelerates when the combined contents satisfy .

Choose one

1 point

How do baryon acoustic oscillations (BAO) help researchers trace the universe’s expansion history?

A
They measure the brightness of distant supernovae.
B
They measure how quickly stars form in distant galaxies.
C
They provide a preferred scale in the galaxy distribution that can be compared at different redshifts.
D
They directly reveal the physical substance responsible for dark energy.

Written response

1 point

The equation-of-state parameter is $w=\frac{p}{\rho}$ . A cosmological constant has what dimensionless value of $w$ ?

Fill in the blank

1 point

If dark energy remains like a positive cosmological constant, the usual long-term outcome in the standard model is the .

Choose all

1 point

Select all the observational methods described as contributing evidence or constraints on cosmic expansion or structure growth.

A
Type Ia supernova brightness and redshift
B
The BAO scale in the distribution of galaxies
C
Direct measurements of atoms expanding with the universe
D
The CMB combined with later-universe measurements
E
Weak gravitational lensing and galaxy clustering

Choose one

1 point

What distinguishes dynamical dark-energy models such as quintessence from a cosmological constant?

A
A field changes over time, so $w$ need not remain at $-1$ .
B
The vacuum energy is constant and necessarily keeps $w=-1$ .
C
Dark matter is replaced by a preferred scale in the galaxy distribution.
D
Expansion must eventually stop and reverse.

True or false

1 point

True or false: The reported preferences for time-varying dark energy establish that dark energy has been confirmed to change over time.

A
True
B
False

Choose all

1 point

Select all accurate conditional descriptions of possible cosmic fates.

A
A positive cosmological constant is associated with a Big Freeze.
B
If dark energy’s equation of state stays below $w=-1$ , a Big Rip is a possible outcome.
C
If dark energy weakens enough or becomes negative, expansion could reverse into a Big Crunch.
D
The Big Crunch is established as the inevitable outcome by current observations.

Choose one

1 point

What role does the cosmic microwave background (CMB) play in studying cosmic expansion?

A
It directly measures the current pressure of dark energy without relying on other observations.
B
It measures early-universe conditions and, with later-universe measurements, helps constrain geometry and expansion history.
C
It tracks only the growth of structure in the late universe.
D
It proves that dark energy is a cosmological constant.

Written response

1 point

For a cosmic component with density $\rho$ and pressure $p=-0.5\rho$ , what is the numerical value of $\frac{\rho+3p}{\rho}$ ?

Open ended

1 point

Why do tests of modified gravity compare measurements of cosmic expansion with measurements of structure growth?

Choose one

1 point

Which description best explains what the BAO scale represents in observations of galaxies?

A
The characteristic brightness of the earliest stars.
B
A preferred scale in the distribution of galaxies, left by sound waves in the early universe.
C
The distance between bound atoms as cosmic expansion proceeds.
D
A direct measurement of the vacuum energy’s physical origin.

Choose one

1 point

The universe's expansion is accelerating on very large scales. Why does this not mean that atoms, solar systems, and galaxies generally expand with it?

A
They are expanding at the same rate as the universe, but are too small to observe.
B
Gravity and other forces hold bound structures together even as distances between unbound galaxies increase.
C
Dark energy affects only the space inside atoms.
D
The scale factor describes the sizes of galaxies rather than the universe.

Choose one

1 point

Which statement best distinguishes dark matter from dark energy in the material?

A
Dark matter causes acceleration, while dark energy holds galaxies together.
B
Both names refer to the same component, but at different cosmic scales.
C
Dark matter attracts gravitationally and helps build structure; dark energy is associated with accelerated expansion.
D
Dark energy builds cosmic structure, while dark matter causes accelerated expansion.

Choose one

1 point

How did observations of distant Type Ia supernovae provide evidence for cosmic acceleration?

A
Their brightness and redshift showed that distant supernovae were farther away than expected if expansion were only slowing under gravity.
B
Their redshift directly measured the pressure of dark energy inside each supernova.
C
Their peak brightness showed that the universe's expansion had stopped.
D
Their distances showed that dark matter was not attracting galaxies.

True or false

1 point

True or false: If dark energy's equation-of-state parameter stays below $w=-1$ , a speculative Big Rip scenario could eventually disrupt structures, but this is not the standard $\Lambda$ CDM prediction.

A
True
B
False

Written response

1 point

In units where the speed of light is 1, what is the equation-of-state parameter $w$ for a cosmological constant?

Written response

1 point

If dark energy remains like a positive cosmological constant, what is the usual name for the expected long-term outcome in which the cosmos becomes increasingly cold and dilute?