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What is dark energy? | Live Science



Dark energy is an enigmatic phenomenon that counteracts gravity and is responsible for accelerating the expansion of the universe. Although Dark Energy accounts for three quarters of the mass energy of the cosmos, its underlying nature continues to elude physicists. Dark Energy has no real connection to Dark Matter except that it shares the word dark, which just means that scientists do not really know what those things are.

Who discovered the dark energy?

The realization that the universe is expanding can be traced back to American astronomer Edwin Hubble, who discovered in 1929 that the farther away a galaxy is from Earth, the faster it moves away from us. Hubble Space Telescope Website . This does not mean that our planet is the center of the universe, but that everything in space moves away from everything else at a constant rate.

Nearly 60 years after Hubble's discovery, scientists made another surprising discovery. Researchers had long sought to accurately measure cosmic distances by looking at the light of distant stars. In the late 1

990s, two independent teams found after the investigation of distant supernovae that the light of the starbursts is weaker than expected. This indicates that the universe is not only expanding, but also accelerating.

This discovery has since given the physicists reason to scratch their heads, and introduced their discoverers the Nobel Prize for Physics 2011 .

What does Dark Energy do?

Although the researchers do not fully understand the dark energy, they have used their knowledge of the phenomenon to construct models of the universe that explain everything from the Big Bang to the modern large-scale structure of galaxies. Some of these models predict that the Dark Energy will rupture everything that exists in billions of years .

The leading explanation of dark energy suggests that it is a kind of pent-up energy that is inherent in matter in space-time. "This simple model works very well in practice and is a simple complement to the cosmological model without having to change the law of gravity," said Baojiu Li, a mathematical physicist at Durham University in the United Kingdom, vs. Live Science . The idea, however, poses a major problem: physicists predict that the value of the energy of the vacuum should be 120 orders of magnitude greater than what cosmologists observe during measurements, Li said.

An alternative idea is that dark energy is one additional fundamental force connecting the already known four forces (gravity, electromagnetism and the strong and weak nuclear forces). However, this assumption does not explain why people do not notice this extra force in our daily lives. That's why theoreticians have also built creative models that suggest that this mysterious force is in some way hidden.

The measured value of dark energy is currently the subject of intense debate between rival factions in physics. Some researchers have measured the performance of dark energy using the cosmic microwave background, a faint echo of the Big Bang, and made an estimate.

Other astronomers who measure the strength of dark energy using light from distant cosmic objects have created a different value, and no one has been able to explain the discrepancy so far. Some experts have suggested that the power of dark energy varies over time, although proponents of the idea have not convinced the majority of their peers about this explanation.

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