Last year, we reported on an exciting hint of new physics in the first data analysis results from the Dark Energy Spectroscopic Instrument (DESI)—namely that the dark energy, rather than being constant, might vary over time. Granted, those hints were still below the necessary threshold to claim discovery and hence fell under the rubric of “huge, if true.”
But now we have more data from DESI, combined with other datasets, and those hints have gotten significantly stronger—so much so that Mustapha Ishak-Boushaki of the University of Texas at Dallas, who co-chairs one of the DESI working groups, said that “we are getting to the point of no return” for confirming dynamical dark energy. Ishak-Boushaki and several other DESI team members presented their results at the American Physical Society’s Global Physics Summit today in Anaheim, California. Several relevant papers have also been posted to the physics arXiv.
Einstein’s cosmological constant (lambda) implied the existence of a repulsive form of gravity. (For a more in-depth discussion of the history of the cosmological constant and its significance for dark energy, see our 2024 story.) Quantum physics holds that even the emptiest vacuum is teeming with energy in the form of “virtual” particles that wink in and out of existence, flying apart and coming together in an intricate quantum dance. This roiling sea of virtual particles could give rise to dark energy, giving the Universe a little extra push so that it can continue accelerating. The problem is that the quantum vacuum contains too much energy: roughly 10120 times too much.