The universe ’s puzzlingly fast expansion may defy explanation, cosmologists fret

Discovered less than a century ago, the expansion of the universe causes galaxies to rush away from Earth, stretching their light to longer, redder wavelengths. That observation spawned the idea of the big bang—and decades of bickering over the rate at which the universe is expanding, the Hubble constant. After a brief rapprochement, cosmologists are arguing again. Working from our cosmic neighborhood outward to more distant galaxies, one group has measured a rate significantly higher than the one derived by colleagues studying the cosmos’ farthest fringe and the afterglow of the big bang, the cosmic microwave background (CMB). Recent observations from NASA’s JWST space telescope have confirmed the disparity, or Hubble tension, and chances that it can be explained as an observational artifact are fading. But so are prospects that the puzzle has a simple physics solution, a recent spate of papers shows. That may dash hopes that solving the Hubble tension could also help cosmologists sharpen their problematic theory of the universe’s makeup and evolution. “There’s no guarantee that there’s one effect that is causing all of this,” says Adam Riess, a cosmologist at Johns Hopkins University. Some question whether the Hubble tension will ever be explained. “I wouldn’t bet my house on it,” says Sunny Vagnozzi, a cosmologist at the University of Trento. According to cosmologists’ prevailing theory , the universe contains 5...
Source: Science of Aging Knowledge Environment - Category: Geriatrics Source Type: research