Gravitational Lensing Offers New Clues About the Universe’s Expansion Rate

Astronomers continue to explore how fast the universe expands. However, their methods often disagree. This disagreement has created a long-running puzzle known as the Hubble tension.A recent study from the University of Tokyo adds an important perspective. The team used gravitational lensing to check the universe’s expansion without relying on traditional distance markers. As a result, they gained a fresh way to confirm or question earlier measurements.

Expansion Rates Matter

The universe continues to grow, even though its true size remains uncertain. Scientists estimate its expansion using the Hubble constant. For example, nearby galaxies suggest a rate of about 73 kilometers per second per megaparsec.Another estimate comes from the cosmic microwave background. That method points to a lower value of 67. The gap between these numbers continues to spark debate.

Time-Delay Cosmography Works

The team applied a technique called time-delay cosmography. Light from distant quasars travels around massive galaxies along different paths. These paths take slightly different amounts of time.Researchers studied these delays to calculate the expansion rate. In addition, they mapped how mass spreads across the lensing galaxies, which helps improve accuracy.

The New Results Suggest

The team’s measurements support the higher expansion rate. Therefore, the results strengthen the case that the tension reflects real physics rather than simple error. Their findings also match several modern observations from space and ground-based telescopes.The researchers analyzed eight lens systems and plan to study more. Increasing the sample size should improve precision and move the field closer to a clear answer. Future work may finally reveal why early and late measurements disagree, and whether new physics is waiting to be uncovered.