How fast is the universe expanding? Cosmic 'illusions' may hold answer.

The article focuses on using gravitationally lensed supernovae, particularly SN Requiem, to measure the Hubble constant—the rate of the universe’s expansion—and potentially resolve the ongoing discrepancy known as the Hubble tension. This method, called time-delay cosmography, leverages the time delays between multiple images of a single supernova caused by a massive galaxy cluster’s gravitational lensing to calculate absolute distances without relying on traditional “standard candles” or assumptions about dark matter and dark energy. Recent advances, including observations from the James Webb Space Telescope (JWST) and integral field spectrographs, have improved mass modeling of lensing clusters, enhancing the precision of these measurements. Upcoming surveys by telescopes such as the Vera C. Rubin Observatory and Euclid are expected to discover many more lensed supernovae, which could provide the data needed to definitively determine the Hubble constant and clarify the universe’s expansion history. [Extracted from the article]