The dark energy pushing our universe apart may not be what it seems, scientists say

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

Astronomers know that the universe is being pushed apart at an accelerating rate and they have puzzled for decades over what could possibly be speeding everything up. They theorize that a powerful, constant force is at play, one that fits nicely with the main mathematical model that describes how the universe behaves. But they can't see it and they don't know where it comes from, so they call it dark energy.

It is so vast it is thought to make up nearly 70% of the universe — while ordinary matter like all the stars and planets and people make up just 5%.

But findings published earlier this year by an international research collaboration of more than 900 scientists from around the globe yielded a major surprise. As the scientists analyzed how galaxies move they found that the force pushing or pulling them around did not seem to be constant. And the same group published a new, broader set of analyses Tuesday that yielded a similar answer.

“I did not think that such a result 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 clustered throughout time and across space. That gives scientists information about how the universe evolved, and where it might be heading.

The map they are building would not make sense if dark energy were a constant force, as it is theorized. Instead, the energy appears to be changing or weakening over time. If that is indeed the case, it would upend astronomers' standard cosmological model. It could mean that dark energy is very different than what scientists thought — or that there may be something else altogether going on.

“It’s a time of great excitement, and also some head-scratching and confusion,” said Bhuvnesh Jain, a cosmologist at the University of Pennsylvania who is not involved with the research.

The collaboration's latest finding points to a possible explanation from an older theory: that across billions of years of cosmic history, the universe expanded and galaxies clustered as Einstein's general relativity predicted.

The new findings aren't definitive. Astronomers say they need more data to overturn a theory that seemed to fit together so well. They hope observations from other telescopes and new analyses of the new data over the next few years will determine whether the current view of dark energy stands or falls.

“The significance of this result right now is tantalizing,” said Robert Caldwell, a physicist at Dartmouth College who is not involved with the research, "but it's not like a gold-plated measurement."

There’s a lot riding on the answer. Because dark energy is the biggest component of the universe, its behavior determines the universe’s fate, explained David Spergel, an astrophysicist and president of the Simons Foundation. If dark energy is constant, the universe will continue to expand, forever getting colder and emptier. If it’s growing in strength, the universe will expand so speedily that it’ll destroy itself in what astronomers call the Big Rip.

“Not to panic. If this is what’s going on, it won’t happen for billions of years," he said. “But we'd like to know about it.”

Associated Press video journalist Mary Conlon reported from New York.

The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Science and Educational Media Group. The AP is solely responsible for all content.

The Dark Energy Spectroscopic Instrument (DESI) making observations in the night sky on the Nicholas U. Mayall 4-meter Telescope at Kitt Peak National Observatory in Tucson, Ariz. (Peter Toman Tomas Slovinsky/NSF's NOIRLab via AP)

This Dec. 14, 2023 image made available by NOIRLab shows meteors from the Geminid meteor shower streaking across the sky above the Nicholas U. Mayall Telescope at Kitt Peak National Observatory (KPNO), a Program of NSF's NOIRLab, in Tucson, Ariz. (NSF's NOIRLab via AP)

ATLANTA (AP) — After almost a year of testimony in a sweeping gang and racketeering indictment against Young Thug and an initial other 27 defendants, prosecutors rested their case Tuesday in the longest trial in Georgia's history.

Both Deamonte Kendrick, also known as Yak Gotti, and Shannon Stillwell told the judge Tuesday they would not testify in their own defense. Both earlier rejected plea offers after over a week of negotiation.

Defense lawyers indicated that they would ask Fulton County Superior Court Judge Paige Reese Whitaker to direct the jury to issue a verdict of not guilty against Kendrick and Stillwell on Wednesday, which requires the lawyers to argue that no reasonable person could find that the state had proved Kendrick and Stillwell guilty.

If Whitaker rejects the request for a directed verdict, lawyers are also likely Wednesday to argue about instructions to jurors about what they must find to convict Kendrick and Stillwell.

Jurors will return on Thursday and could begin deliberation before the end of the week.

Young Thug, the 33-year-old Atlanta-born Grammy winning artist whose given name is Jeffery Williams, pleaded guilty to gang, drug and gun charges in October after negotiations with prosecutors broke down. That left the sentence up to Whitaker, who gave him a 40-year sentence that let him walk free on probation with hefty restrictions, including a ban from the metro Atlanta area for the first 10 years except for certain occasions.

The slow-moving trial has been fraught with problems from the start. Jury selection took nearly 10 months, and Fulton County Superior Court Judge Ural Glanville, the original judge, was removed from the case in July after defense attorneys filed a recusal motion based on a secretive meeting he held with prosecutors and a state witness.

Whitaker took over the case and often lost patience with prosecutors for what she once called “poor lawyering.” She and defense attorneys scolded prosecutors for not sharing evidence in advance.

More than 175 witnesses testified throughout the trial. Prosecutors alleged that Young Thug and two others co-founded a violent criminal street gang in 2012 called Young Slime Life, or YSL, which they say is affiliated with the national Bloods gang.

At Young Thug's plea hearing, defense attorney Brian Steel said that Young Thug was “falsely accused" and the evidence against him was weak. He also condemned the use of rap lyrics during the trial.

Steel said he thought they were winning the trial and wanted to stick it out to a jury verdict, but Young Thug wanted to go home to his family instead of sitting through the rest of the trial, which felt like “hell.”

Nine people charged in the indictment, including Atlanta rapper Gunna, whose real name is Sergio Kitchens, accepted plea deals before the trial began. Twelve others are to be tried separately. Prosecutors dropped charges against one defendant after he was convicted of murder in an unrelated case.

FILE - Judge Paige Reese Whitaker answers the question as she hears arguments for several motions the trial of Atlanta rapper Young Thug, whose real name is Jeffery Williams, July 30, 2024, at the Fulton County courtroom in Atlanta. (Miguel Martinez/Atlanta Journal-Constitution via AP, File)