# Gravitational mass defect

In nuclear physics we have a mass defect by the binding energy of the nuclides. A similar effect appears in the theory of gravitation induced by the gravitational binding energy, which reduces the mass. But for example at the ISCO of an Kerr black hole we have binding energies about $\sim 0.4 mc^2$ so if a particle would go to $r\to 0$ the binding energy $E_B\to-\infty$ and so the effective mass will be negative (and the mass defect will also be infinite)?

• The Penrose process: (en.wikipedia.org/wiki/Penrose_process) relies that the effective energy of a particle near a Kerr black hole can be negative. Nov 27 '15 at 19:10
• Sure but Penrose associated this negative energy as an extraction of the rotational energy from the black hole. So I think this isn't the same? Nov 27 '15 at 19:50