Using the ultra-sensitive eyes of the James Webb Space Telescope (JWST), researchers have taken a fresh look at an old puzzle—one that might force us to rethink the fundamentals of cosmology. Two Answers, One UniverseFor years now, astronomers have noticed that the universe’s expansion rate—something called the Hubble constant—just doesn’t add up. This tension between the two values has earned a name of its own: the Hubble tension. If two of the most advanced telescopes ever built agree on the expansion rate, then the problem isn’t the data—it’s the theory. By independently confirming the expansion rate measured by Hubble, the telescope has eliminated the last major source of doubt surrounding the Hubble tension.