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An ergosphere is a defined region of space surrounding a rotating black hole. According to general relativity (GR), the space surrounding such a black hole rotates along with it, space's rotation being quickest adjacent to the event horizon and falling off with distance from the black hole, this rotation of the surrounding space termed frame dragging. The ergosphere is defined to be the set of locations where this dragged space is moving the speed of light or faster in relation to distant space, e.g., to us. The impossibility of moving beyond the speed of light applies to the relative speed of objects both within the same relatively-flat space, but does not apply to objects distant from each other between which space is being so-deformed.