evaluate the trajectories of light wrt black holes and General Relativity. Its pretty interesting. I'll just ask this question: Will the astronaut falling radially be able to 'see' his feet after he crosses the event horizon? For GR all the mass of the black hole is at r=0 (commonly referred to as the 'singularity') and all the surrounding space between the horizon and r=0 has a vacuum solution. Think about it.