New Study Says that Dark Energy Could be Growing in Strength

By Chelsea Gohd | January 31, 2019 4:17 pm
Credit: Illustration: NASA/CXC/M.Weiss; X-ray: NASA/CXC/Univ. of Florence/G.Risaliti & E.Lusso

An illustration of quasars stretching farther and farther away from Earth. In one new study, researchers have found evidence to support the idea that dark energy may be growing with time. (Credit: Illustration: NASA/CXC/M.Weiss; X-ray: NASA/CXC/Univ. of Florence/G.Risaliti & E.Lusso)

Dark Energy

Dark energy, the mysterious and hypothetical force that scientists think is causing the expansion of the universe to accelerate, may actually be growing over time, according to one new study.

About 20 years ago, scientists discovered dark energy by measuring the light coming from exploding stars, known as supernovas. Dark energy is thought to permeate all of space and, by continuing to study the light coming from supernovas, scientists have observed the effects of dark energy at great distances in the cosmos. Up until now, researchers have been able to track dark energy’s effects up to about 9 billion years ago.

Whatever it is, dark energy seems to be pushing things in the universe apart from each other.

“If the universe contained only mass, it could only decelerate as a consequence of the gravitational braking. The acceleration implies the existence of a repulsive force, which is what we call ‘dark energy,'” paper co-author Guido Risalti of the University of Florence said in an email. And so, while the existence of the mysterious force hasn’t yet been confirmed, scientists watch its effects by studying the expansion of the universe.

With this new study, researchers Risalti and Elisabeta Lusso of Durham University used data from NASA’s Chandra X-ray Observatory and the ESA’s XMM-Newton space observatory to track the expansion of the universe from about 13 billion years ago to today. This allowed the researchers to track how the universe’s expansion rate, and therefore dark energy, has changed over time.

Tracking Quasars

To track the expansion of the universe, the team used ultraviolet (UV) and X-ray data to estimate the distances of 1,598 quasars — extremely bright, faraway active galactic nuclei — to Earth.

By observing and studying UV and X-ray data from these quasars, the team was able to figure out their luminosity.

“From the luminosity, we can infer the distance [from Earth], and distances are what we need to track the expansion of the Universe,” Risalti explained. With the distances of all 1,598 quasars calculated, the researchers were able to track the universe’s expansion rate back through time. And, with their findings, the team found evidence that dark energy seems to be getting denser over time, which would mean it’s growing in strength.

Now, especially since the existence of dark energy hasn’t yet been confirmed, these researchers do make clear that it’s just one explanation for their findings.

“I am not certain at all,” Risalti said of whether expanding dark energy is a certainty. “It is a possible extension of the standard model, but it is a long way to saying this interpretation is unique or is the best one.”

However, if the team’s findings are confirmed, it could imply that the universe might expand more quickly in the future, Risalti explained.

“If we ‘select’ this interpretation, it means that the density, and so the importance, of dark energy will increase with time, and so the universe will expand more and more rapidly in the future,” Risalti said. 

This new study is reported in the latest issue of Nature Astronomy. A preprint is available on the arXiv.

CATEGORIZED UNDER: Space & Physics, top posts
MORE ABOUT: cosmology
  • Uncle Al

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  • OWilson

    According to the Big Bang theory, what started off as an expanding point of primeval matter, later went into an unexplained accelerated “inflation” phase (Guth) which settled down again to a steady expansion rate. It “explains” (makes the equations balance) what we observe today.

    This Dark Matter can be useful, if invisible. It can always be tweaked to do what we need it to do! :)

  • Kurt Stocklmeir

    all of these are my theories – neutrinos are negative energy tachyons – they emit anti gravity- if space is expanding negative energy particles will have an increase of energy – this can be compared to positive energy particles will have a decrease of energy – all forces get more strong as they travel – anti gravity gets more strong as it travels – run away expanding space could be made – neutrinos make anti gravity – anti gravity makes space expand – because space expands neutrinos get more energy – because neutrinos have more energy they make more anti gravity – more anti gravity makes space expand more fast – space is not expanding a lot if it is expanding – if space is expanding a lot – neutrinos flying around space would have a lot more energy compared to what they have at this time – the big bang did not happen – if the big bang happened there would be a lot more neutrinos and the neutrinos would have a lot of energy – all forces travel only a certain distance – anti gravity travels only a certain distance – shape of time and space around mass makes a force that is away from mass – it can be compared to anti gravity – it helps to make inertia – it fights against gravity – gravity travels only a certain distance – when there is not any more gravity from mass shape of time and space associated with the mass is still making a force that is away from mass – it is like anti gravity – at a big distance from mass there is only a force that is away from mass – the force is small and does not do a lot of things to the universe Kurt Stocklmeir

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