Cosmic Acceleration Without Dark Energy? New GR-Based Model Claims Yes

A new paper argues that the universe’s accelerating expansion can be explained purely within Einstein’s general relativity by treating Friedmann spacetimes as unstable during the early radiation era, producing accelerations that mimic dark energy without needing a cosmological constant or exotic energy. If borne out, this approach could replace or modify the standard lambda-CDM model, though its adoption remains uncertain.