" * DESI’s latest analysis is based on its first three years of data, covering almost 15 million galaxies and quasars.
* The team combined DESI data with results from other experiments, including studies of the cosmic microwave background (CMB), supernovae, and weak gravitational lensing.
* When viewed together, the full range of data is difficult to reconcile with the standard cosmological model (Lambda CDM).
* A model in which dark energy evolves over time appears to better explain the combined observations.

Mayall Telescope Star TrailsDESI maps distant objects to study dark energy. The instrument is installed on the Mayall Telescope, shown here beneath star trails. Credit: KPNO/NOIRLab/NSF/AURA/B. Tafreshi
Dark Energy’s Role in the Universe’s Fate

The future of the universe depends on the balance between matter and dark energy, the mysterious force driving its accelerating expansion. New findings from the Dark Energy Spectroscopic Instrument (DESI), which has created the most detailed 3D map of the cosmos, reveal how dark energy has influenced the universe over the past 11 billion years. Scientists have detected hints that dark energy, long believed to be a fixed "cosmological constant,” may instead be evolving in unexpected ways.

DESI is a global collaboration of over 900 researchers from more than 70 institutions, led by the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab). The team has released its latest results in multiple papers on arXiv and presented them at the American Physical Society’s Global Physics Summit in Anaheim, California.
DESI InstrumentDESI is a state-of-the-art instrument and can capture light from up to 5,000 celestial objects simultaneously. Credit: Marilyn Sargent/Berkeley Lab
Hints of an Evolving Dark Energy

"What we are seeing is deeply intriguing,” said Alexie Leauthaud-Harnett, co-spokesperson for DESI and a professor at UC Santa Cruz. "It is exciting to think that we may be on the cusp of a major discovery about dark energy and the fundamental nature of our universe.”

Taken alone, DESI’s data are consistent with our standard model of the universe: Lambda CDM (where CDM is cold dark matter and Lambda represents the simplest case of dark energy, where it acts as a cosmological constant). However, when paired with other measurements, there are mounting indications that the impact of dark energy may be weakening over time and that other models may be a better fit. Those other measurements include the light leftover from the dawn of the universe (the cosmic microwave background or CMB), exploding stars (supernovae), and how light from distant galaxies is warped by gravity (weak lensing)."

Posted by: Dana Mathewson at March 25, 2025 10:21 PM (Idemf)

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