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What is dark energy?
What is dark energy?
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Dark energy is a theoretical form of energy that is believed to be responsible for the observed accelerating expansion of the universe. It is called “dark” because it does not interact with light or other forms of electromagnetic radiation, making it difficult to detect or observe directly.
The existence of dark energy was first proposed in the late 1990s when astronomers were studying distant supernovae (exploding stars) and found that the expansion of the universe was actually accelerating, contrary to what was expected based on the known forces and matter in the universe. This discovery led to the concept of dark energy as an explanation for this unexpected acceleration.
Dark energy is thought to permeate all of space and have a constant density. It is believed to exert a negative pressure that counteracts the attractive force of gravity, causing the expansion of the universe to accelerate over time. In other words, it is as if there is a repulsive force pushing galaxies and other cosmic structures apart.
The nature of dark energy is still not well understood, and it remains one of the biggest mysteries in modern astrophysics. Various theoretical models have been proposed to explain its origin and properties, including the possibility that it arises from fluctuations in the vacuum of space or from a new fundamental particle. However, no conclusive evidence or direct detection of dark energy has been made to date.
Dark energy is estimated to constitute about 70% of the total energy content of the universe, with dark matter accounting for about 25% and ordinary matter (the stuff we are familiar with) making up the remaining 5%. While dark energy’s exact nature and origin are yet to be determined, its presence is inferred from its observed effects on the expansion of the universe.
