A long-simmering disagreement over the universe’s present-day expansion rate shows no signs of resolution, leaving experts increasing ly vexed.

By Anil Ananthaswamy edited by Lee Billings

Over the past decade, two very different ways of calculating the rate at which the universe is expanding have come to be at odds, a disagreement dubbed the Hubble tension, after 20th-century astronomer Edwin Hubble. Experts have speculated that this dispute might be temporary, stemming from subtle shortcomings in observations or analyses that will eventually be corrected rather than from some flawed understanding of the physics of the cosmos. Now, however, a new study that relies on an independent measure of the properties of galaxies has strengthened the case for the tension. Quite possibly, it’s here to stay.