What is the fastest Possible rotational velocity for a pulsar ? There must be a point where it requires an infinity of energy to go any faster. There is also a point where it becomes a black hole. How exactly does velocity relate to a fundamental shift in terms of how matter changes spacetime in such a fundamental way ? Relativity describes it but doesn't explain it, just like the quantum formalism. Maybe my question can be summed up thus; what is the difference between energy in black holes, energy in matter, and energy in em radiation ?