Could black hole mergers finally solve the Hubble tension? Probably not

image via Space.com

August 25, 2025, 5:00 PM

• •Black holes would need to merge at an unrealistic rate to account for the Hubble tension.
• •The actual number of black hole mergers is roughly 10,000 times smaller than the number required to explain the Hubble tension.

Cosmologists are grappling with the Hubble tension, a discrepancy in the measurement of the universe's expansion rate. One potential solution involves the mass loss during black hole mergers, but new research suggests this is unlikely. Researchers found that the required merger rate of black holes to explain the Hubble tension is astronomically high. The actual rate is far too low to resolve the discrepancy, leaving the mystery unresolved. While not providing a solution, this research represents a crucial step in the ongoing investigation of the Hubble tension.

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