Analysis of 168 Gravitational-Wave Events Finds No Break in Einstein’s General Relativity

A new analysis from the LIGO-Virgo-KAGRA collaboration found no evidence that gravitational waves are departing from Albert Einstein’s general theory of relativity, even after examining 168 high-confidence cosmic collisions — the largest sample yet used for this kind of test. The result, posted July 21 in the preprint “GWTC-5.0: Tests of General Relativity,” sharpens several earlier limits on possible cracks in the theory.

The collaboration reported that, after subtracting the best-fit general relativity waveforms from the detector data, the leftover signal in every event was consistent with ordinary detector noise. It also found no strong evidence for additional gravitational-wave polarizations beyond the two tensor polarizations predicted by general relativity. In another set of checks tied to how merging objects generate gravitational waves, the team said it improved constraints on possible deviations by roughly 1.2 to 2.6 times compared with prior catalog-wide results.

That matters because gravitational waves let physicists test gravity under extreme conditions that cannot be recreated in the Solar System: the violent mergers of black holes and neutron stars, where gravity is strong and rapidly changing. The field is also shifting from headline-making single detections to catalog-scale measurements, where many events are combined to look for subtle patterns. As Leo Tsukada of the University of Nevada Las Vegas said in a LIGO press release in May, “Nearly 400 gravitational-wave events accumulated in our catalog have ushered us into a new era of statistical astronomy—where this growing collection of detected signals enables population studies and tests of general relativity with unprecedented precision.”

The new paper is a companion to the broader fifth Gravitational-Wave Transient Catalog, or GWTC-5.0, but it is not the same thing as the main event release. The full catalog added 161 new events from O4b, the second part of the fourth observing run, bringing the running total to 390 candidate events. For the relativity tests, however, the collaboration used a stricter subset: only “confident” events seen in at least two detectors, with estimated false-alarm rates of 10^-3 per year or lower. That produced a 168-event sample, including 72 events from O4b and five O4a events that became significant after updated searches, along with events from earlier observing runs.

One event, GW250114, had an especially large effect on the results. In catalog discussions, the signal is described as the loudest gravitational-wave event observed so far, with a reported network matched-filter signal-to-noise ratio of 76.9. The new paper says that unusually clear detection helped tighten some of the combined constraints, underscoring how a single exceptionally strong event can still move the needle even in an era of population-level studies.

The paper also includes caveats that keep the result measured rather than sweeping. In analyses of the merger remnant, the data were overall consistent with general relativity in both time-domain and frequency-domain ringdown studies, which examine how the newly formed black hole settles down after the collision. But in the frequency-domain combination, the general relativity prediction landed in the tails of the combined result. The authors say that may reflect the still-limited catalog size and subtleties in the analysis and event selection, not evidence of a real deviation. They also note that for one event, GW240621_195059, spurious high-frequency content prevented a robust spectroscopic constraint from that signal alone, even though its postmerger data were consistent with the dominant Kerr black hole mode and its first overtone. The paper’s bottom line is direct: “Overall, we find no evidence for physics beyond GR.”