&gt; Why do people just seem to completely ignore relativity when dealing with black holes?<p>It&#x27;s true that, at and below the event horizon, spacetime curvature is such that time hasn&#x27;t its usual meaning, but this doesn&#x27;t mean two BHs cannot orbit closer and closer and eventually merge. Such events take place primarily outside the event horizon. This video --<p><a href="http:&#x2F;&#x2F;www.galacticcenter.astro.ucla.edu&#x2F;animations.html" rel="nofollow">http:&#x2F;&#x2F;www.galacticcenter.astro.ucla.edu&#x2F;animations.html</a><p>-- diagrams stars orbiting close to the BH said to be at the center of our galaxy (in fact these orbits give us an estimate of the BH&#x27;s mass).<p>So if stars can orbit a BH, then a BH can orbit a BH, and the latter would orbit in normal spacetime, at least until the merger.<p>&gt; Because of time dilation this merger will take infinite time.<p>Only from the perspective of the event horizon and below. Remember that &quot;above&quot; the event horizon, time still has its usual meaning, even though it&#x27;s greatly modified compared to time on Earth&#x27;s surface (which is also slightly dilated in GR).