Hello, 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 energys about ~0.4 mc² so if a particle would go to r→0 the binding energy EB→-∞ and so the effective mass will be negative (and the mass defect will also be infinite)? What is the problem about this thoughts? Thanks for help.