Gravitational lens time delays refine Hubble constant

Tokyo, Japan (SPX) Dec 09, 2025

Astronomers are testing a new way to measure how fast the universe is expanding by using time delays in gravitationally lensed images of distant quasars, in an effort to clarify the long-standing tension between different measurements of the Hubble constant.

The expansion rate of the universe, known as the Hubble constant, describes how quickly galaxies recede as a function of distance, wi