Faint Cosmic Hum May Unlock Universe Expansion Puzzle

New gravitational wave technique could help resolve Hubble tension

Published on Mar. 2, 2026

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A group of astrophysicists and cosmologists have introduced a new way to calculate the Hubble constant, which measures the universe's expansion rate, using gravitational waves. Their approach improves the precision of earlier gravitational wave-based techniques and could help scientists close the gap behind the Hubble tension - the mismatch between measurements of the early and recent universe expansion rates.

Why it matters

Resolving the Hubble tension is one of the most important unresolved problems in modern cosmology. If the tension persists, it could signal that scientists need to revise their understanding of the early universe. This new gravitational wave-based method provides an independent measurement that could help reconcile the conflicting expansion rate estimates.

The details

The researchers showed that if the Hubble constant were lower, the total observable volume of the universe would also be smaller, increasing the overall strength of the gravitational-wave background. By studying this background signal, they were able to rule out particularly slow expansion rates and achieve a more precise estimate of the Hubble constant. As gravitational-wave observatories improve, this 'stochastic siren' strategy should become even more powerful.

  • The findings have been accepted for publication in Physical Review Letters and will appear in the March 11 issue.
  • Scientists expect the gravitational-wave background to be detected within about six years.

The players

Nicolás Yunes

Illinois Physics Professor and founding director of the Illinois Center for Advanced Studies of the Universe (ICASU).

Daniel Holz

UChicago Professor of Physics and of Astronomy & Astrophysics and a co-author of the research.

Bryce Cousins

Illinois physics graduate student, NSF Graduate Research Fellow, and lead author of the study.

LIGO-Virgo-KAGRA (LVK) Collaboration

A global network with more than 2,000 members that detects gravitational wave signals on Earth.

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What they’re saying

“This result is very significant -- it's important to obtain an independent measurement of the Hubble constant to resolve the current Hubble tension. Our method is an innovative way to enhance the accuracy of Hubble constant inferences using gravitational waves.”

— Nicolás Yunes, Illinois Physics Professor (Mirage News)

“It's not every day that you come up with an entirely new tool for cosmology. We show that by using the background gravitational-wave hum from merging black holes in distant galaxies, we can learn about the age and composition of the universe. This is an exciting and completely new direction, and we look forward to applying our methods to future datasets to help constrain the Hubble constant, as well as other key cosmological quantities.”

— Daniel Holz, UChicago Professor of Physics and of Astronomy & Astrophysics (Mirage News)

What’s next

As gravitational-wave observatories improve, this strategy should become even more powerful. Scientists expect the gravitational-wave background to be detected within about six years. Until then, increasingly strict limits on the background signal will continue to narrow the possible range of the Hubble constant.

The takeaway

This new gravitational wave-based method provides an independent measurement that could help resolve the Hubble tension, one of the most important unresolved problems in modern cosmology. As gravitational wave detection technology advances, this approach has the potential to sharpen future measurements of the universe's expansion rate.