NASA’s James Webb Space Telescope has confirmed the universe is expanding at a rate that is about 8% faster than theoretical models suggest mystery that has puzzled scientists for over a decade. The finding corroborates observations by the Hubble Space Telescope and adds to a growing scientific mystery called “Hubble Tension.”
The two-year study by Webb, published in the Astrophysical Journal, confirms Hubble’s measurements and therefore rules out an instrument error as the explanation behind the anomaly. “This is the largest Webb Telescope data sample so far, and it confirms the puzzling findings we’ve grappled with for over a decade,” said Adam Riess of Johns Hopkins University, a Nobel laureate and an astrophysicist.
According to the standard model of cosmology, the Hubble Constant, which measures the expansion rate of the universe, should be about 67–68 kilometers per second per megaparsec. However, these new measurements from Hubble and Webb range from about 70 to 76 kilometers per second per megaparsec, averaging 73. All these discrepancies point toward a failure in understanding some of the main components of the universe, such as dark energy and dark matter, which constitute about 96% of the universe.
Dark energy is an enigmatic force that appears to be speeding up the expansion of the universe, while dark matter is an invisible substance its presence was inferred from gravitational effects. Some explanations that have been advanced by scientists include those touching on exotic properties of gravity, contributions from dark radiation, and neutrinos. However, the Webb findings would appear to say that these models of cosmology might need revision.
With the Webb Telescope, three independent ways of measuring distances to galaxies hosting Cepheid stars returned consistent results with Hubble. These observations cover one-third of Hubble’s galaxy sample, extending partial validations done earlier.
Riess emphasized that what was needed was further data to refine the scale of this anomaly and find out where it was coming from. “We need to characterize this clue better. Is the mismatch closer to 4-5% or as high as 10-12%? These insights will inform future theories,” he said.
The Hubble Tension is among the most serious challenges to astrophysics, pushing scientists to reconsider the basic concepts of the theory describing the universe’s evolution. For the time being, the findings from the Webb Telescope deepen the mystery and invite further exploration of the cosmos.
