Is the Hubble Tension Starting to Go Away?

For years, scientists have been scratching their heads over the "Hubble Tension,” the mismatch between how fast the cosmos expanded in its youth versus how fast it's expanding today. But now, armed with the most precise data ever captured by the James Webb Space Telescope, astronomers have found the perceived gap is staring to narrow!I n fact, the expansion rate measured by Cepheid variables versus the cosmic background has overlapping error bars again. Will the tension mystery finally be resolved?

Jun 5, 2025 - 12:24
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Is the Hubble Tension Starting to Go Away?

Scientists have made a new calculation of the speed at which the universe is expanding, using the data taken by the powerful new James Webb Space Telescope on multiple galaxies. Above, Webb’s image of one such galaxy, known as NGC 1365. Credit Image courtesy of NASA, ESA, CSA, Janice Lee (NOIRLab), Alyssa Pagan (STScI)

For years, scientists have been scratching their heads over the "Hubble Tension,” the mismatch between how fast the cosmos expanded in its youth versus how fast it's expanding today. But now, armed with the most precise data ever captured by the James Webb Space Telescope, astronomers have found the perceived gap is staring to narrow!I n fact, the expansion rate measured by Cepheid variables versus the cosmic background has overlapping error bars again. Will the tension mystery finally be resolved?