Primordial Magnetic Fields Offer Clue to Hubble Tension

Scientists have identified tiny magnetic fields generated shortly after the Big Bang that could resolve the long‑standing discrepancy in the universe’s expansion rate, known as the Hubble tension. Using detailed simulations, researchers found that these primordial fields would alter the way hydrogen formed in the early cosmos. The changes in hydrogen chemistry would, in turn, affect the cosmic microwave background radiation, the primary data source for measuring the expansion rate. By accounting for these magnetic effects, the inferred expansion rate from the background radiation aligns more closely with local measurements, potentially reconciling the two approaches.