The Power of Nothing: Vacuum Energy Explained Quiz

The correct answer is B because vacuum energy refers to the energy inherent to space itself. According to quantum mechanics, even a perfect vacuum is not truly empty but contains fluctuating fields that possess a baseline level of energy.

This statement is true. In modern cosmology, the energy of the vacuum is the leading explanation for dark energy. Because this energy belongs to space itself, it provides the constant outward pressure needed to explain why the expansion of the universe is accelerating.

Constant is the correct term. The cosmological constant, represented by the Greek letter Lambda, is a mathematical way to describe a uniform density of vacuum energy that fills all of space and never changes over time.

Options A, C, and D are correct. Unlike matter, which spreads out as space expands, the density of vacuum energy stays the same. This constant energy results in a negative pressure that pushes the fabric of the universe outward.

The correct choice is B. In general relativity, if the energy density of a substance remains constant while space expands, it must exert a negative pressure. This unique "tension" is what causes the expansion of the universe to speed up.

The correct answer is B. Quantum mechanics states that pairs of virtual particles constantly pop in and out of existence in a vacuum. These fluctuations mean that the lowest possible energy state of space is not zero, giving the vacuum its own energy.

This is false. While the term pressure often implies a push, negative pressure in the context of general relativity actually works as a repulsive force on the fabric of space, driving galaxies further apart rather than pulling them together.

Options A and D are correct. Data from distant supernovae show the universe is accelerating, and the microwave background shows the total energy density of the universe requires a large amount of vacuum energy to match observations.

Expands is the correct answer. Because vacuum energy is a property of space itself, as more space is created through expansion, the total volume of vacuum energy in the universe grows, even though its density remains the same.

The correct answer is B. Positive pressure, like that found in a tank of gas, adds to the gravitational pull. If vacuum energy worked this way, it would help gravity slow down the expansion of the universe rather than speeding it up.

The correct answer is B. Vacuum energy is inherent to the fabric of space time. Even if you removed every atom and photon from a region of space, the vacuum energy would still exist at the same constant density.

This is true. The Casimir Effect is a small attractive force measured between two uncharged metal plates in a vacuum. It is caused by the way the plates affect the quantum fluctuations of the vacuum energy between them, proving the energy exists.

Options A and C are correct. Vacuum energy is the primary explanation for why the expansion rate of the universe changed from slowing down to speeding up, and it dictates whether the universe will expand forever.

The correct choice is A. The theory of cosmic inflation suggests that a massive burst of vacuum energy and negative pressure caused the universe to expand exponentially in the first fractions of a second after the Big Bang.

Dark is the correct term. Because we cannot see vacuum energy directly and it only interacts with the universe through gravity and expansion, it is categorized as dark energy, which makes up about 70 percent of the total universe.

The correct answer is B. Calculations from quantum physics predict a massive amount of vacuum energy, but astronomical observations show a much smaller amount. Resolving this huge difference is one of the biggest challenges in science today.

This is false. This is the defining characteristic of vacuum energy. Unlike matter or radiation, which dilute as space grows, the density of vacuum energy remains perfectly constant regardless of how much the universe expands.

Options A and C are correct. Dark energy is defined by its invisibility and its role in accelerating the expansion of space. It is non-baryonic, meaning it is not made of standard atoms like protons or neutrons.

The correct choice is B. The balance between the density of matter and the negative pressure of vacuum energy determines the overall shape of space. Current data shows this balance results in a universe that is very nearly flat.

Cosmology is the correct answer. It is the branch of science that uses physics and astronomy to build a history of the universe, using evidence like vacuum energy to explain how the cosmos evolved from its origin.