Recent analyses of data from the LIGO-Virgo-KAGRA (LVK) network's fourth observing run have rigorously tested Einstein's theory of general relativity (GR) in the extreme environment of black hole mergers. Three new papers examined gravitational wave signals from these cosmic events, focusing on overall consistency with GR, deviations from Newtonian gravity using post-Newtonian parameters, and the absence of predicted gravitational echoes from the post-merger black hole remnants. While all three studies found that GR remains an excellent fit to the observed data, ruling out certain alternative gravitational models, they also established new experimental bounds on the mass of gravitons, suggesting they are less than 2 x 10-23 eV/c². This advancement signifies that gravitational wave astronomy now possesses the precision to probe the limits of gravity in strong-field regimes, paving the way for future discoveries.