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New Insights Suggest Dark Energy is Evolving Over Time

WASHINGTON – Recent research involving vast datasets from millions of galaxies and luminous astrophysical objects has unveiled compelling evidence that dark energy, which drives the accelerated expansion of the universe, may be diminishing rather than remaining constant. This challenges long-standing theories about the nature of this elusive force.

The findings were revealed during a press briefing and are the culmination of an extensive investigation into cosmic history, particularly focusing on dark energy. The analysis utilized observations gathered over three years by the Dark Energy Spectroscopic Instrument (DESI) at Kitt Peak National Observatory in Arizona.

According to Arjun Dey, an astrophysicist at the U.S. National Science Foundation’s NOIRLab and project scientist for DESI, “The DESI results tantalizingly hint at an evolving dark energy.” This exploratory study examined data from nearly 15 million galaxies and quasars—extremely bright galactic nuclei dominated by supermassive black holes devouring surrounding material.

The integration of these findings with other astrophysical observations suggests that dark energy’s influence may be declining over time, prompting scientists to reconsider the standard model of cosmology. These additional measurements include remnants of light from the universe’s infancy, supernova explosion data, and gravitational lensing effects that warp the light from far-off galaxies.

“Our results imply that whatever is driving the expansion of the universe might be weakening—essentially decreasing in strength,” Dey elaborated. “This development alters our foundational understanding of nature, particularly regarding the future trajectory of our universe. Will the expansion persist indefinitely, or will it eventually decelerate?”

Since the Big Bang—an event that transpired approximately 13.8 billion years ago—the universe has been continuously expanding. In 1998, researchers noted that this expansion was not just ongoing but accelerating, with dark energy postulated as the underlying cause, though its true nature remains a mystery.

Jeff Newman, an astrophysicist at the University of Pittsburgh and a contributor to the research, explained, “The DESI data informs us about how the universe’s size has evolved over time. We can directly link the universe’s growth rate to the energy density of dark energy, which is responsible for that acceleration.”

Current understanding posits that the universe comprises ordinary matter—such as stars and planets—alongside dark matter and dark energy. Ordinary matter accounts for approximately 5% of the universe’s total mass, while dark matter, inferred from its gravitational effects, may constitute about 27%. Dark energy, on the other hand, is believed to make up about 68% of the universe.

Dey acknowledged, “Dark energy is undeniably one of the most perplexing components of our universe. While its exact nature remains unknown, its influence on cosmic expansion is unmistakable.”

“All matter in the universe possesses gravity, which should result in a slowed expansion rate. Contrary to this expectation, we observe that the expansion of the universe is accelerating, an anomaly attributed to dark energy, which functions as a form of pressure that propels objects apart—similar to a negative gravitational force,” he added.

These groundbreaking results were discussed at the American Physical Society’s Global Physics Summit held in Anaheim, California.

Mustapha Ishak, a cosmologist at the University of Texas at Dallas and co-chair of the working group analyzing the DESI data, remarked, “Our findings indicate that dark energy is evolving over time, rather than remaining the cosmological constant. This is arguably the most significant discovery regarding cosmic acceleration since it was first identified in 1998, which led to the Nobel Prize in Physics awarded in 2011.” He further emphasized that this unexpected development could fundamentally reshape the field of cosmology along with its prevailing models.

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www.yahoo.com