What is dark energy?

In Physics of Cosmology and Astronomy, dark energy is an unknown form of energy that accounts for most of the universe and tends to speed up the expansion of the universe. Dark energy is the most accepted theory since the 1990s, indicating that the universe is expanding with increasing speed.

Dark energy is said to account for 68% of the universe , while dark matter accounts for about 27%. The rest includes everything on Earth, all we can observe, accounting for less than 5% of the universe.

Dark energy is explained as a characteristic of space . Albert Einstein was the first to understand that space is not simply empty. The space has a lot of amazing properties and many new features are being explored.

Imagine the proportion of the cosmic component.

In theory of force, Einstein introduced a cosmological constant to predict that empty space could have its own energy. Because this energy is a characteristic of space, it will not be lost when space expands. So the more space that exists, the more dark energy of space will appear.

As a result, this type of energy will make the universe expand faster. However, no one understands why cosmological constants exist and why it is the exact value that causes the expansion of the universe.

Another explanation of the dark energy of space is given in the quantum theory of matter. In this theory, "empty space" is actually temporary elements that constantly form and disappear afterwards.

Another explanation of dark energy is that it is a type of energy field or liquid in all spaces. Some theorists name dark energy as the fifth element . But if this is the answer, we still don't know how that element is, how it interacts and why it exists. Therefore, the correct answer about dark energy is still a mystery.

Some theorists name dark energy as the fifth element.

One final possibility is Einstein's theory of gravity is not accurate. That not only affects the expansion of the universe, but also affects how the normal reaction of matter in galaxies and galaxy clusters.

This also requires a new theory of gravity to find the answer to dark energy. What kind of theory is that? Can it accurately describe the movement of celestial bodies in the Solar System? There are many theories that have been proposed, but none of them are convincing. So dark energy remains a mystery.