New Gravitational Methods Aim to Resolve Hubble Tension in Cosmology
Two independent groups of astronomers are developing new methods to measure the Hubble constant, a parameter describing the universe's expansion rate, to address the Hubble tension. This discrepancy arises from conflicting results produced by existing measurement techniques. One group, based in Germany, is using gravitationally-lensed supernovae, while a U.S. team is employing gravitational waves. The German team observed a superluminous supernova, SN 2025wny, which can be studied using ground-based telescopes. This allows for time-delay cosmography, a method that calculates the Hubble constant by measuring the time difference in light paths deflected by massive galaxies. Meanwhile, the U.S. team is exploring the gravitational-wave background, which could provide a lower limit on the Hubble constant. 
