Gravitational waves refine cosmic expansion rate ⚡ экспресс
Впервые объединили сигналы гравитационных волн от слияния нейтронных звёзд с данными о распределении и искривлении света галактиками. Это позволило измерить скорость расширения Вселенной: 68 км/с на мегапарсек. Новый метод может разрешить загадку, почему разные измерения дают разную скорость.
Measuring the universe’s expansion is like timing a race when the track stretches. Neutron star mergers act as standard sirens: their gravitational waves ring out with a known “volume,” so fainter signals mean greater distance.
A new study paired the siren from merger GW170817 with a galaxy map tracing matter, including dark matter (invisible mass first detected by Vera Rubin). The result: the Hubble constant (named after Edwin Hubble) is 67.9 km/s per megaparsec—so a galaxy 3.26 million light-years away recedes at that speed—with just 6.4% uncertainty.
This value eases a cosmic dispute: the early universe’s afterglow suggests slower expansion, while nearby exploding stars point to faster. The new number falls between them, highlighting the strength of cross-checking methods. Remarkably, the spacetime ripples from GW170817 jiggled our detectors by less than a proton’s width, yet clocked the universe’s growth.
🎯 The term 'standard siren' echoes 'standard candle,' but while candles use light, sirens use gravitational waves—a clever twist on an old cosmic yardstick.