The Great Speedup: Accelerated Expansion of the Universe Quiz

  • 11th Grade
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| Questions: 20 | Updated: Feb 20, 2026
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1. Why did astronomers conclude the expansion of the universe is accelerating based on Type Ia supernovae observations

Explanation

The correct answer is B because if the expansion were constant or slowing down, distant supernovae would be closer and brighter. Finding them to be fainter than predicted implies they are further away, meaning the expansion rate must have increased over the billions of years the light traveled to reach us.

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About This Quiz
The Great Speedup: Accelerated Expansion Of The Universe Quiz - Quiz

Witness the 1998 discovery that changed our understanding of cosmic destiny. This Accelerated Expansion of the Universe Quiz covers the surprising observation that the universe is pushing itself apart faster and faster. Review how this discovery led to the conclusion that gravity is being overcome by a mysterious, repulsive force.

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2. Dark energy is a repulsive force that counteracts the pull of gravity on a cosmic scale

Explanation

This statement is true because gravity acts to pull matter together and slow down expansion, whereas dark energy acts on the vacuum of space to push it apart. The discovery of acceleration proves that on a global scale, the repulsive effect of dark energy is currently stronger than the attractive pull of gravity.

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3. Scientists use Type Ia supernovae as standard _____ because their known peak luminosity allows them to calculate distance

Explanation

The term standard candles is the correct answer because it refers to astronomical objects with a known intrinsic brightness. By comparing this fixed brightness to how dim the object looks from Earth, scientists can calculate an exact distance, which is necessary to track the history of the universe's expansion rate.

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4. Which observations provided the foundational evidence used to construct the Big Bang model

Explanation

Options A, B, and C are correct because the afterglow of the Big Bang, the recession of galaxies, and the chemical ratio of hydrogen to helium are the three pillars of the model. While water on planets is interesting, it does not provide evidence for the origin or expansion rate of the entire universe.

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5. What is the primary role of the cosmological constant in modern expansion theories

Explanation

The correct choice is B because the cosmological constant represents energy inherent to space itself. This energy provides the outward pressure required to drive the accelerated expansion of the universe. It does not measure stellar heat or calculate the specific mass of dark matter particles.

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6. How does the redshift of light from distant galaxies relate to the speed of cosmic expansion

Explanation

Option B is correct because redshift is a direct result of the stretching of space. As the expansion of the universe speeds up, the light waves traveling through that space are stretched to a greater degree, causing a larger shift toward the red end of the spectrum for more distant objects.

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7. In an accelerating universe galaxies that are not bound by gravity will eventually move beyond our observable horizon

Explanation

This is true because the rate of expansion increases with distance. Eventually, the space between us and a distant galaxy will be expanding faster than the speed of light. At that point, the light from that galaxy can never reach us, making it invisible and placing it beyond the observable limit.

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8. Which of the following describe a potential outcome of the universe if dark energy continues to dominate

Explanation

Options A and B are correct because they describe scenarios where expansion continues forever. The Big Freeze involves the universe becoming too cold for star formation, while the Big Rip involves expansion becoming so violent that it tears atoms apart. The Big Crunch only occurs if expansion stops and reverses.

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9. The point in time when the repulsive force of dark energy overcame the pull of matter is called dark energy _____

Explanation

Dominance is the correct term because for the first few billion years of the universe, matter was dense enough for gravity to slow expansion. As space grew and matter spread out, the constant energy of the vacuum became the stronger force, causing the transition from a slowing expansion to an accelerating one.

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10. What does the Hubble constant specifically measure in the context of an evolving universe

Explanation

The correct answer is B because the Hubble constant is the unit of measurement for the recession velocity of galaxies per unit of distance. While it has changed over billions of years, its current value helps scientists determine the expansion rate and the overall age of the cosmos.

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11. Why is the discovery of accelerated expansion significant for the Big Bang theory

Explanation

Option B is correct because the Big Bang model originally assumed gravity would slow expansion. The discovery of acceleration forced scientists to integrate dark energy into the model to explain why the expansion is speeding up, thereby refining our understanding of the universe's total energy composition.

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12. Observations of the Cosmic Microwave Background support the conclusion that the universe is currently accelerating

Explanation

This is true because detailed maps of the microwave background allow scientists to calculate the total matter and energy density of the universe. When these values are combined with supernova data, they confirm that dark energy makes up 70 percent of the universe, which is required for acceleration to occur.

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13. What factors contribute to the deceleration of the universe's expansion in its early stages

Explanation

Options A and B are correct because all matter exerts a gravitational pull that acts to slow down expansion. In the early universe, matter was packed closely together, so its gravity was the dominant force. Dark energy only became dominant later as the universe expanded and matter density decreased.

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14. How did the discovery of acceleration change our understanding of the age of the universe

Explanation

The correct answer is B because knowing the expansion rate changed from slowing down to speeding up allows scientists to "rewind" the clock more accurately. This refined expansion history aligns with the age of the oldest star clusters, providing a consistent timeline for the history of the cosmos.

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15. If the expansion of the universe were slowing down distant supernovae would appear _____ than they actually do

Explanation

Brighter is the correct answer because if the expansion were decelerating, those distant objects would not be as far away as they are now. Being closer would make them appear brighter. The fact that they are fainer than that "slowdown" prediction is the evidence that the expansion is actually accelerating.

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16. What is the relationship between the density of dark energy and the volume of space

Explanation

Option B is correct because dark energy is considered a property of space itself. Unlike matter, which becomes less dense as space grows, the energy of the vacuum stays the same per cubic centimeter. This means as more space is created, the total amount of dark energy in the universe increases.

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17. The accelerating expansion of the universe is a local phenomenon only happening near the Milky Way

Explanation

This is false because the acceleration is a global property of the fabric of the universe. It is observed in every direction we look in deep space. While gravity keeps our local group of galaxies together, the vast voids between all distant galaxy clusters are expanding at an increasing rate everywhere.

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18. Why are light spectra critical for measuring the acceleration of the universe

Explanation

Options B and D are correct because spectra allow us to see how much light has been stretched (redshift). This tells us how fast a galaxy is receding. By combining this speed with the distance from supernovae, we can see how the expansion rate has changed over time.

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19. What would be the effect of a universe with only matter and no dark energy

Explanation

The correct choice is B because matter only provides gravity, which is an attractive force. In a universe containing only matter, there would be no repulsive force to cause acceleration. The expansion would simply coast or gradually decelerate as the gravitational pull of all galaxies worked to slow it down.

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20. The stretching of space-time that causes light from distant galaxies to appear redder is known as _____ redshift

Explanation

Cosmological is the correct answer because this type of redshift is caused by the expansion of the fabric of space itself while the light is in transit. This is distinct from the Doppler effect, which is caused by the local motion of objects through space, and is the key to measuring the universe's expansion.

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Why did astronomers conclude the expansion of the universe is...
Dark energy is a repulsive force that counteracts the pull of gravity...
Scientists use Type Ia supernovae as standard _____ because their...
Which observations provided the foundational evidence used to...
What is the primary role of the cosmological constant in modern...
How does the redshift of light from distant galaxies relate to the...
In an accelerating universe galaxies that are not bound by gravity...
Which of the following describe a potential outcome of the universe if...
The point in time when the repulsive force of dark energy overcame the...
What does the Hubble constant specifically measure in the context of...
Why is the discovery of accelerated expansion significant for the Big...
Observations of the Cosmic Microwave Background support the conclusion...
What factors contribute to the deceleration of the universe's...
How did the discovery of acceleration change our understanding of the...
If the expansion of the universe were slowing down distant supernovae...
What is the relationship between the density of dark energy and the...
The accelerating expansion of the universe is a local phenomenon only...
Why are light spectra critical for measuring the acceleration of the...
What would be the effect of a universe with only matter and no dark...
The stretching of space-time that causes light from distant galaxies...
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