Overview
- An international collaboration reporting in Astronomy & Astrophysics set the universe’s expansion rate at 73.50 ± 0.81 kilometers per second per megaparsec, a result with just over 1% uncertainty.
- The Hubble constant measures how fast galaxies move apart with distance, where one megaparsec equals about 3.26 million light-years.
- Researchers built a Local Distance Network that links many yardsticks, including Cepheid variables, tip of the red giant branch stars, Miras, Type Ia supernovae, megamasers, and galaxy scaling relations.
- The team accounted for shared errors between datasets and found that removing any single technique left the final value essentially unchanged, which undercuts claims that one faulty method drives the gap.
- The result remains well above early‑universe inferences of about 67–68 km/s/Mpc from the cosmic microwave background, pointing to possible gaps in the standard model and setting up open data and software for tests with next‑generation observatories such as the Vera C. Rubin Observatory.