The dark energy tearing apart the universe may not be what it seems, scientists say

NEW YORK (AP) – Distant, ancient galaxies are giving scientists more clues that a mysterious force called dark energy may not be what they thought.

Astronomers know that the universe is being torn apart at high speeds and have been puzzled for decades about what might be speeding everything up. They hypothesize that there is a strong, continuous force, which fits well with the basic mathematical model that explains how the universe behaves. But they don’t see and don’t know where it comes from, so they call it dark power.

It’s so big that it’s thought to make up about 70% of the universe – while ordinary things like all the stars and planets and people make up 5%.

But the findings published earlier this year by an international research collaboration of more than 900 scientists from around the world revealed a big surprise. When scientists analyze the way galaxies move they find that the forces that push or pull them seem to be constant. And the group published a new, comprehensive set of analyzes on Tuesday that provided the same answer.

“I didn’t think such an outcome would happen in my lifetime,” said Mustapha Ishak-Boushaki, a cosmologist at the University of Texas at Dallas who is part of the collaboration.

Called the Dark Energy Spectroscopic Instrument, it uses a telescope based in Tucson, Arizona to create a three-dimensional map of the universe’s 11-billion-year history to see how galaxies have evolved over time and space. That gives scientists information about how the universe came to be, and where it might be headed.

The map they build would make no sense if dark energy were a fixed force, as it is said to be. Instead, the power seems to change or weaken over time. If that is indeed the case, it would suggest a common cosmological model for astronomers. It could mean that dark energy is more different than scientists thought – or that there might be something else going on entirely.

“It’s a time of great excitement, and head-scratching and confusion,” said Bhuvnesh Jain, a cosmologist at the University of Pennsylvania who was not involved in the study.

The recent joint discovery points to a possible explanation from an old theory: that during the billions of years of cosmic history, the universe expanded and galaxies merged as predicted by Einstein’s general relativity.

The new findings are inconclusive. Astronomers say they need more data to disprove the theory that seemed to fit so well. They hope that observations from other telescopes and new analyzes of new data in the next few years will determine whether the current theory of dark energy stands or collapses.

“The significance of this effect is now surprising,” said Robert Caldwell, a physicist at Dartmouth College who was not involved in the study, “but it’s not like a gold-plated standard.”

There is a lot riding on the answer. Because dark energy is the largest element in the universe, its behavior determines the fate of the universe, explains David Spergel, an astrophysicist and president of the Simons Foundation. If dark energy does not change, the universe will continue to expand, forever cold and empty. If it grows stronger, the universe will expand so fast that it will destroy itself in what astronomers call the Big Rip.

“Not to panic. If this happens, it won’t happen for billions of years,” he said. “But we would like to know about it.”

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Associated Press video reporter Mary Conlon reported from New York.

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