What if dark energy isn't constant? New data hints at a surprising answer.

Using data from DESI, SDSS, and recent supernova catalogs without forcing assumptions about how dark energy evolves, researchers reconstructed its density and behavior across 7 time slices from now back 12 billion years. They found dark energy density rose then fell, its equation of state wobbled around the cosmological constant, and tentatively crossed into "phantom" territory around z~0.6–0.8. The signal is modest (2–3σ) but consistent across different datasets and robust to varying spatial curvature and neutrino mass.