At the moment, it would tell us more about cosmology than about the underlying physics, were we not to detect the gravitational waves. We expect gravitational

At the moment, it would tell us more about cosmology than about the underlying physics, were we not to detect the gravitational waves. We expect gravitational waves to be emitted from two black holes as they orbit very close to each other, just before they merge. From general relativity, we know how big of gravitational waves to expect. However, we don't know how many such black hole mergers occur in nearby space. LIGO can only measure gravitational waves down to a certain strength, and so we can only detect waves that are caused by black hole mergers within some distance of Earth. Predictions of how many such mergers occur vary wildly, depending on the assumptions in the model. (I don't have exact numbers, and would appreciate if anyone does have the numbers.) If we did not detect gravitational waves, I would use that as a lower bound of the number of black hole mergers, rather than as a breaking of general relativity.