"Ah. They don't exist in any physical space, so that question isn't any more meaningful than talking about directions. It's all metaphors in english. Alright, imagine you are seeing the normal three dimensions, but then you turn and see a fourth, and then you turn again and find yourself existing in five dimensions. The dimensions' existence is similar to that. There is always another dimension curled up in the place you didn't look. Time isn't especially meaningful. A lot of the directions lead to universes we can't understand. We typically ignore those."