Complex sentence: For binary black holes numerical solution of the two body problem was achieved after four for decades of intense research, in 2005 (annus mirabilis of numerical relativity) when three groups devised the breakthrough techniques.
Split into simpler sentences: For binary black holes numerical solution of the two body problem was achieved after four for decades of intense research. In 2005 (annus mirabilis of numerical relativity) when three groups devised the breakthrough techniques.