I see theres an abundance of black hole questions here. Welp, here's another: In reference to rotating (Kerr) black holes...so I get that theres an oblate sphere shaped ergosphere around a rotating BH, and that due to frame dragging, points on the sphere exactly are where spacetime is being dragged at light speed, and point inside are being dragged faster than light speed. Then I read two confusing things. ONE: The coordinates are of time and angle are swapped, so time becomes angle and angle becomes time. Why? I've got some ideas brewing around but nothing I can organzie enough to sum up here. TWO: Somehow all this frame dragging and coordinate swapping means that matter can have positive energy, negative energy, or both at once? Again, why? I get that the Penrose process has alot to do with that, and get the point of the Penrose process, but if someone could help tie all three ideas together, I'd be pumped. Thanks.