New data involving millions of galaxies and luminous galactic cores is providing fresh evidence that the enigmatic and invisible cosmic force called dark energy - responsible for the universe's accelerated expansion - has weakened over time rather than remaining constant,

Scientists with the Dark Energy Spectroscopic Instrument (DESI), an international research collaboration, presented new evidence Wednesday that bolstered its recent finding that dark energy is not inexorably pushing the universe apart at a constant rate of acceleration but rather ebbs and flows and appears to be weakening.