\u201cThis is the dream of every physicist. Find something wrong in our understanding so we can discover something new and profound,\u201d added Simon Birrer, Assistant Professor of Physics at the Stony Brook University and one of the corresponding authors of the study.\u00a0<\/p>\n
![\"\"](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2025\/12\/hubble_tension_small-1024x695.png\")
Researchers using time-delay cosmography independently confirmed that the universe\u2019s current rate of expansion, known as the Hubble constant (H\u2080), does not match values predicted from measurements from the universe when it was much younger. This \u201cHubble tension\u201d may point to new physics governing the universe. Credit: W. M. Keck Observatory \/ Adam MakarenkoA Constant in Question Questioned Constantly<\/p>\n
Coined by astronomer Edwin Hubble, who first calculated it in 1929, the Hubble Constant is the rate at which the universe expands. This number reveals not only the universe\u2019s current speed of growth, but also its age and history.<\/p>\n
Yet nearly a century later, scientists still can\u2019t agree on its exact value. The Hubble Constant can be measured in two ways, one probing the universe at early times and another probing the universe at times near today. The early universe probe, which uses cosmological models to indirectly provide the current expansion rate of the universe, favors an expansion rate of ~67 km\/s\/Mpc; and the late (nearby) universe probe, which measures the local universe as it exists today favors an expansion rate of 73 km\/s\/Mpc. Measurements based on the nearby universe differ from predictions drawn from the early universe, resulting in what is famously known as the Hubble Tension.<\/p>\n
Confirming this tension would force scientists to rethink the very makeup of the cosmos; perhaps revealing new particles, or evidence for an \u201cearly dark energy\u201d phase that briefly accelerated expansion after the Big Bang. Because the implications are so profound, astronomers stress the importance of multiple independent methods to cross-check the result.<\/p>\n
\u201cThis is significant in that cosmology as we know it may be broken,\u201d said John O\u2019Meara, Chief Scientist and Deputy Director of Keck Observatory. \u201cIf it is true that the Hubble Tension isn\u2019t a mistake in the measurements, we will have to come up with new physics.\u201d<\/p>\n
A New Way to Measure the Universe<\/p>\n
To make this precise measurement, the team used a method called time-delay cosmography. Much like a funhouse mirror bends and distorts reflections, massive galaxies bend the light of more distant galaxies and quasars, producing multiple images of the same object.<\/p>\n
When the distant object\u2019s brightness changes, astronomers can measure how long it takes those changes to appear in each image. Those \u201ctime delays\u201d act like cosmic yardsticks \u2014 allowing scientists to calculate distances across the universe and, ultimately, determine how fast it\u2019s expanding.<\/p>\n
KCWI\u2019s powerful spectroscopy was essential to the measurement. By observing the motion of stars within the lensing galaxies, the instrument revealed how massive those galaxies are and how strongly they bend light, critical information for pinning down the Hubble Constant.<\/p>\n
\u201cThe key breakthrough relied on the motion of stars in the lens galaxies as measured via Keck\/JWST\/VLT spectroscopy to address the main source of uncertainty, known as the mass-sheet degeneracy. The result also relies on long-term collaborative work between observatories including time delay measurements from 20 years of photometric data obtained at ESO in Chile,\u201d said Anowar Shajib, postdoctoral fellow at the University of Chicago, and a corresponding author of the study.<\/p>\n
The Quest Continues<\/p>\n
The team\u2019s measurement currently achieves 4.5% precision \u2014 an extraordinary feat, but not yet enough to confirm the discrepancy beyond doubt. The next goal is to refine that precision to better than 1.5%, a level of certainty \u201cprobably more precise than most people know how tall they are,\u201d noted Martin Millon, postdoctoral fellow at ETH Zurich and the third corresponding author of the study.<\/p>\n<\/p>\n
ABOUT KCWI
The Keck Cosmic Web Imager (KCWI) is designed to provide visible band, integral field spectroscopy with moderate to high spectral resolution formats and excellent sky-subtraction. The astronomical seeing and large aperture of the telescope enables studies of the connection between galaxies and the gas in their dark matter halos, stellar relics, star clusters, and lensed galaxies.\u00a0KCWI covers the blue side of the visible spectrum; the instrument also features the Keck Cosmic Reionization Mapper (KCRM), extending KCWI\u2019s coverage to the red side of the visible spectrum. The combination of KCWI-blue and KCRM provides simultaneous high-efficiency spectral coverage across the entire visible spectrum. Support for KCWI was provided by the National Science Foundation, Heising-Simons Foundation, and Mt. Cuba Astronomical Foundation. Support for KCRM was provided by the National Science Foundation and Mt. Cuba Astronomical Foundation.<\/p>\n
ABOUT ADAPTIVE OPTICS
W. M. Keck Observatory is a distinguished leader in the field of adaptive optics (AO), a breakthrough technology that removes the distortions caused by the turbulence in the Earth\u2019s atmosphere.\u00a0 Keck Observatory pioneered the astronomical use of both natural guide star (NGS) and laser guide star adaptive optics (LGS AO) and current systems now deliver images three to four times sharper than the Hubble Space Telescope at near-infrared wavelengths.\u00a0AO has imaged the four massive planets orbiting the star HR8799, measured the mass of the giant black hole at the center of our Milky Way Galaxy, discovered new supernovae in distant galaxies, and identified the specific stars that were their progenitors. Support for this technology was generously provided by the Gordon and Betty Moore Foundation, Mt. Cuba Astronomical Foundation, NASA, NSF, and W. M. Keck Foundation.<\/p>\n
ABOUT W. M. KECK OBSERVATORY
The W. M. Keck Observatory telescopes are among the most scientifically productive on Earth. The two 10-meter optical\/infrared telescopes atop Maunakea on the Island of Hawai\u02bbi feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrometers, and world-leading laser guide star adaptive optics systems.\u00a0Some of the data presented herein were obtained at Keck Observatory, which is a private 501(c) 3 non-profit organization operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the Native Hawaiian community.\u00a0We are most fortunate to have the opportunity to conduct observations from this mountain.<\/p>\n","protected":false},"excerpt":{"rendered":"New results strengthen the \u201cHubble tension,\u201d hinting at the need for rethinking our model of the universe Maunakea,…\n","protected":false},"author":2,"featured_media":333966,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[49],"tags":[199,79],"class_list":{"0":"post-333965","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-physics","8":"tag-physics","9":"tag-science"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/333965","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/comments?post=333965"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/333965\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media\/333966"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media?parent=333965"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/categories?post=333965"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/tags?post=333965"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}