{"id":579454,"date":"2026-04-12T08:31:18","date_gmt":"2026-04-12T08:31:18","guid":{"rendered":"https:\/\/www.newsbeep.com\/us\/579454\/"},"modified":"2026-04-12T08:31:18","modified_gmt":"2026-04-12T08:31:18","slug":"the-local-universes-expansion-rate-is-clearer-than-ever-but-still-doesnt-add-up","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/us\/579454\/","title":{"rendered":"The Local Universe\u2019s Expansion Rate Is Clearer Than Ever, but Still Doesn\u2019t Add Up"},"content":{"rendered":"


\n \"Cerro
\n <\/a><\/p>\n


\n \"Kitt
\n <\/a><\/p>\n

\n noirlab2611 \u2014 Science Release\n <\/p>\n

A new synthesis of astronomical measurements confirms a persistent mismatch that could point to physics beyond current models<\/p>\n

10 April 2026<\/p>\n

An international collaboration of astronomers has produced one of the most precise measurements yet of how fast the local Universe is expanding. The result deepens one of the most significant challenges in modern cosmology. John Blakeslee, astronomer at NSF NOIRLab, funded by the U.S. National Science Foundation, is a member of the collaboration, and telescopes across two NSF NOIRLab Programs contributed data.<\/p>\n

Astronomers have sought to measure the expansion rate of the Universe using two fundamentally different approaches. One method relies on measuring distances to stars and galaxies in the nearby Universe. The other uses measurements of the cosmic microwave background<\/a> to predict what the expansion rate would be today under the standard model of cosmology<\/a>.<\/p>\n

These two approaches are expected to yield the same result, but they don\u2019t. Measurements based on the nearby Universe consistently indicate a higher expansion rate \u2014 around 73 kilometers per second per megaparsec \u2014 while predictions derived from the early Universe yield a lower value, closer to 67 or 68. Although the numerical difference is modest, it is far larger than can be explained by statistical uncertainty. This persistent disagreement, known as the Hubble tension<\/a>, has now been observed across multiple independent studies and techniques.<\/p>\n

By bringing together decades of independent observations into a single, unified framework, an international collaboration of astronomers has achieved the most precise direct measurement to date of the expansion rate of the nearby Universe. In a paper<\/a> published on 10 April in Astronomy & Astrophysics, the H0 Distance Network (H0DN) Collaboration reports a value of the Hubble constant of 73.50 \u00b1 0.81 kilometers per second per megaparsec, corresponding to a precision of just over 1%.<\/p>\n

The study, \u201cThe Local Distance Network: a community consensus report on the measurement of the Hubble constant at \u223c1% precision,\u201d is the outcome of a broad community effort launched at the International Space Science Institute (ISSI) Breakthrough Workshop, \u201cWhat\u2019s under the H0od?\u201d<\/a>, held at ISSI in Bern, Switzerland, in March 2025.<\/p>\n

\u201cThis isn\u2019t just a new value of the Hubble constant,\u201d the collaboration notes, \u201cit\u2019s a community-built framework that brings decades of independent distance measurements together, transparently and accessibly.\u201d<\/p>\n

NSF NOIRLab contributed both expertise and observational data to this effort. John Blakeslee, astronomer and Director of Research and Science Services at NSF NOIRLab, is a member of the collaboration. The study includes data from telescopes at NSF Cerro Tololo Inter-American Observatory (CTIO<\/a>) in Chile and NSF Kitt Peak National Observatory (KPNO<\/a>) in Arizona, both Programs of NSF NOIRLab. Those data were incorporated into a broader, collaborative framework spanning both ground and space-based observatories, helping to strengthen the overall result.<\/p>\n

Rather than relying on a single method, the team constructed a \u201cdistance network\u201d that links many overlapping techniques for measuring distances across the local Universe. These include observations of pulsating Cepheid variable stars<\/a>, red giant stars<\/a> that shine with a known brightness, Type Ia supernovae<\/a>, and certain types of galaxies. This approach enables multiple independent paths to the same final result, and allows for a critical test: is the discrepancy caused by an error within a single method? The results indicate that this is unlikely. Even when individual techniques are removed from the analysis, the overall result changes only minimally. Independent measurements remain consistent with one another, reinforcing the robustness of the locally measured expansion rate.<\/p>\n

\u201cThis work effectively rules out explanations of the Hubble tension that rely on a single overlooked error in local distance measurements,\u201d the authors conclude. \u201cIf the tension is real, as the growing body of evidence suggests, it may point to new physics beyond the standard cosmological model.\u201d<\/p>\n

The implications are significant. The lower expansion rate inferred from the early Universe depends on the standard model of cosmology, which describes how the Universe has evolved since the Big Bang. If that model is incomplete \u2014 for example, if it does not fully account for the behavior of dark energy<\/a>, new particles, or modifications to gravity \u2014 its predictions for the present-day expansion rate would be affected.<\/p>\n

In that case, the Hubble tension may not be the result of measurement error, but rather evidence that the current model of the Universe is missing a key component. The local distance network also establishes a framework for future investigations. By making its methods and data openly available, the collaboration has created a foundation that can be expanded with new observations. With next-generation observatories expected to provide even more precise measurements, astronomers aim to determine whether this discrepancy will ultimately be resolved or continue to point toward new physics.<\/p>\n

More information<\/p>\n

This research is presented in a paper titled \u201cThe Local Distance Network: A community consensus report on the measurement of the Hubble constant at \u223c1% precision\u201d to appear in Astronomy & Astrophysics. DOI: 10.1051\/0004-6361\/202557993<\/a><\/p>\n

The results are presented by the H0DN Collaboration.<\/p>\n

NSF NOIRLab<\/a>, the U.S. National Science Foundation center for ground-based optical-infrared astronomy, operates the International Gemini Observatory<\/a> (a facility of NSF<\/a>, NRC\u2013Canada<\/a>, ANID\u2013Chile<\/a>, MCTIC\u2013Brazil<\/a>, MINCyT\u2013Argentina<\/a>, and KASI\u2013Republic of Korea<\/a>), NSF Kitt Peak National Observatory (KPNO<\/a>), NSF Cerro Tololo Inter-American Observatory (CTIO<\/a>), the Community Science and Data Center (CSDC<\/a>), and NSF\u2013DOE Vera C. Rubin Observatory<\/a> (in cooperation with DOE<\/a>\u2019s SLAC<\/a> National Accelerator Laboratory). It is managed by the Association of Universities for Research in Astronomy (AURA<\/a>) under a cooperative agreement with NSF<\/a> and is headquartered in Tucson, Arizona.\u00a0<\/p>\n

The scientific community is honored to have the opportunity to conduct astronomical research on I\u2019oligam Du\u2019ag (Kitt Peak) in Arizona, on Maunakea in Hawai\u2018i, and on Cerro Tololo and Cerro Pach\u00f3n in Chile. We recognize and acknowledge the very significant cultural role and reverence of I\u2019oligam Du\u2019ag to the Tohono O\u2019odham Nation, and Maunakea to the Kanaka Maoli (Native Hawaiians) community.<\/p>\n

The International Space Science Institute (ISSI) is an Institute of Advanced Studies, where scientists from all over the world meet in a neutral, welcoming, and multi-disciplinary setting to discuss and publish about relevant and compelling topics related to four Disciplines: Astrophysics, Heliophysics, Planetary Science and Earth Science. ISSI\u2019s mission is to advance science by facilitating scientific community interactions, meetings, discussions, and publications aimed at a deeper understanding of results from different space missions, ground-based observations, and theory. This is achieved through a broad portfolio of scientific opportunities that include: International Teams, Workshops, Working Groups, Fora, or visits of individual Visiting Scientists. For additional information related to ISSI and to the opportunities it offers, see: www.issibern.ch<\/a>.<\/p>\n

Contacts<\/p>\n

\n Josie Fenske
Public Information Officer
NSF NOIRLab
Email: josie.fenske@noirlab.edu<\/a><\/p>\n

\n Fabio Crameri
Communication Scientist
ISSI
Email: fabio.crameri@issibern.ch<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"noirlab2611 \u2014 Science Release A new synthesis of astronomical measurements confirms a persistent mismatch that could point to…\n","protected":false},"author":2,"featured_media":579455,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[48],"tags":[79,193],"class_list":["post-579454","post","type-post","status-publish","format-standard","has-post-thumbnail","category-space","tag-science","tag-space"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/579454","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=579454"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/579454\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media\/579455"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media?parent=579454"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/categories?post=579454"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/tags?post=579454"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}