A conceptual issue that some of the commenters may have missed is that part of the detection is done by matched filtering (<a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Matched_filter" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Matched_filter</a>), in which it is necessary to have a good idea of the signal you&#x27;re looking for.  This detection has built upon analytical and numerical advances in relativity.  While people may not know about the prevalence of e.g. binary black hole collisions, they have a pretty good idea of the signal that would result if such a collision were to occur.  Similarly with other potential sources like binary neutron star collisions.