Primordial Magnetic Fields May Resolve Cosmic Expansion Discrepancy
A longstanding puzzle in cosmology involves the so-called Hubble tension—the discrepancy between different methods of measuring how fast the universe is expanding. Now, researchers have proposed a new explanation rooted in the earliest moments of cosmic history.
Detailed simulations show that primordial magnetic fields, generated mere fractions of a second after the Big Bang, could have influenced the formation of hydrogen in the early universe. This influence would have altered the properties of the cosmic microwave background (CMB)—the relic radiation left over from the Big Bang—and consequently affected the expansion rate inferred from CMB observations.
The research offers a potential pathway to resolving the Hubble tension without requiring modifications to our standard cosmological model. If confirmed, this mechanism would mean that early-universe physics left subtle but measurable imprints on the signals astronomers use to calculate the universe's expansion rate.
Scientists caution that further observational and computational work is needed to validate whether these primordial fields are strong enough to produce the observed effect.