I love to wander in book stores, and sometimes I do a Google wander, which is how I ended up swinging on M-theory, which is my excitement of the day. I had forgotten the strands of string theory, and am now entranced with "loose ends" and closed loops. I have been thinking of other dimensions but not in a mathematical way, which may be the point. I read that Einstein formulated his ideas in his body first, worked through body sensations. Most of his concepts may have come to him in a pre-verbal state.
Pre-verbal! What's there now for you and me?
http://en.wikipedia.org/wiki/M-theory