String theory is eight dimensions, and has been expanded to other numbers. Nobody has tried to explain to me what that means. I get a feeling that it doesn't mean anything, just a sort of mental juggling act.
There was a book written in the 1800s by an Englishman about living in a two dimensional world ... Quite an advanced concept for the time ...I think it was called flatworld or similar .. I can't conceive of a one dimensional object ... Unless it was that guy I went out with once!