A community-built distance network sharpens the Hubble constant and broadens the evidence behind the “Hubble tension”.
BERN, SWITZERLAND – An international collaboration of astronomers has achieved the most precise direct measurement to date of the current expansion rate of the Universe. In a paper to be published in Astronomy & Astrophysics, the H0 Distance Network (H0DN) Collaboration reports a value of the Hubble constant of
H₀ = 73.50 ± 0.81 km s⁻¹ Mpc⁻¹, corresponding to a precision of just over 1%.
The study, “The Local Distance Network: a community consensus report on the measurement of the Hubble constant at ∼1% precision,” is the outcome of a broad community effort launched at the ISSI Workshop “What’s under the H0od?”, held at the International Space Science Institute (ISSI) in Bern in March 2025.
Online Panel Discussion with Stefano Casertano, Richard I. Anderson, Eleonora Di Valentino, Adam Riess and Licia Verde
The Hubble constant is widely acknowledged as a key test of our understanding of cosmology and the history of the Universe: its locally measured value differs from prevailing cosmological predictions with very high significance. The participants in a weeklong ISSI workshop in March have developed a new formalism, the Distance Network, to enable a rigorous analysis of a large, diverse set of distance measurements, yielding a more precise and robust value of the Hubble constant – and strengthening the discrepancy with cosmological predictions. The Distance Network formalism will be made publicly available and has the capability to incorporate future measurements as they become available.
In March 2025, the International Space Science Institute (ISSI) in Bern hosted an inspiring week-long workshop titled “What’s under the H₀od? Towards Consensus on the Local Value of the Hubble Constant”, bringing together some of the world’s leading cosmologists to tackle one of astronomy’s most puzzling problems: the rate at which the universe is expanding. Among them was Prof. Dr. Adam Riess, Nobel Prize-winning astrophysicist from Johns Hopkins University, who co-convened the workshop and also gave a widely attended public lecture as part of ISSI’s outreach series.
