Physicists are waging a cosmic battle over the nature of dark energy

Is dark energy changing, or is it just more of the same? Last month, astronomers announced the startling finding that dark energy – which is thought to cause the accelerating expansion of the universe – might weaken over time. This has forced physicists to consider upending the standard cosmological model of the universe but now, some researchers are saying this may be premature.

Since it started scanning the sky in 2021, the Dark Energy Spectroscopic Instrument (DESI) in Arizona has been carefully measuring the distances between millions of…