Two of the Universe's Great Mysteries May Have Their Own Dimension

Observations by the Dark Energy Spectroscopic Instrument in 2024 and a larger 2025 data set indicate that dark energy’s density peaked about 2 billion years ago and has since declined, suggesting a transition into a “phantom regime.” Theoretical work by Khoury, Lin, Trodden and others proposes models where dark energy and dark matter interact, allowing concurrent changes in dark-energy density and dark-matter mass that could explain the observed evolution.