A team of scientists says it's possible to use tiny ripples in space and time, or gravitational waves, to measure the rate at which our universe is expanding. This could solve one of the biggest mysteries in physics today, a disparity in calculating this rate known as the "Hubble tension."
Scientists have known since 1998 that not only is the universe expanding, but also that the expansion rate is accelerating. "Dark energy" was introduced as a placeholder name for the mysterious force driving this acceleration, but there's an outstanding issue surrounding the universe's expansion rate in general, even after over two decades and a half of investigation.
