ANAHEIM, Calif. Change is in the air. New data strengthen a hint that dark energy, long thought to be constant force in the universe, might change over time.Dark energy explains the observation that the universes expansion rate is accelerating. But its origins are unknown. Its typically expected to have constant density across the billions of years of the universes history. So when researchers from the Dark Energy Spectroscopic Instrument, or DESI, reported in 2024 that dark energy might vary over time based on their first year of data, it shook cosmology to its core.Many scientists expected that the standard picture would prevail with additional data from DESI. But that hasnt happened. Instead, with three years of DESI data, the preference for a changing, or dynamical dark energy has grown.