Gravitational‑wave catalog doubles detections

The LIGO‑Virgo‑KAGRA collaboration published GWTC‑4, adding 128 gravitational‑wave events to previous catalogs and roughly doubling the known sample of black‑hole and neutron‑star mergers. The new events include unusually massive black holes (~130 solar masses), very high spins (~0.4c), lopsided mass ratios, and mixed black hole–neutron star mergers observed at cosmological distances. — A much larger and more diverse gravitational‑wave dataset enables near‑term tests of black‑hole growth channels, precision measurements of the Hubble constant using 'standard sirens', and stronger tests of general relativity.