Question

Discuss dark energy. Include how it was discovered, why scientists believe it exists, its effects on the evolution of the universe, and possibilities of what it might be.

Answer 1

It was in 1998, the Hubble Space Telescope observations of very distant supernovae showed that, a long time ago the universe was expanding more slowly than it is today. Hence expansion of universe is not slowing down due to gravity, it is accelerating due to unknown reason. Still we don't know the reason but Scientist has given name to this mystery- dark energy. Hence dark energy is solution to the problem of acceleration of expansion of universe. Scientist believe that it exist since there must be some reason for acceleration in expansion of universe.

Dark energy has great role in evolution of universe. Cosmologists estimate that the acceleration began roughly 5 billion years ago. Before it dark matter was dominate and due to its gravity expansion was decelerating. After time passed dark matter becomes diluted and dark energy becomes dominated.

Dark energy can be the property of space. The cosmological constant in general relativity has one prediction that empty space has its own energy. This is property of space and hence it is not diluted with expansion of universe and more energy is stored when more space is formed. This form of energy cause universe to expand faster and faster.

Another possibility is that general relativity is wrong and we need new theory of gravity to incorporate dark energy.

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