How the Universe Works - Season 6 Episode 1

Various eminent scientists explain the current knowledge of Black Holes and try to answer the question, do they really exist? The two great theories of Einstein's General Relativity and Quantum Mechanics don't work together to explain Black Holes which is a big problem. Other theoretical constructs such as Gravastars and Planck stars have been postulated but proving their existence is just as difficult as that of Black Holes. So where next?