I read (or heard or saw) somewhere long ago that if you traveled as far as you could go in the Universe you'd return to the exact same point at which you started. If our U is indeed a 'brane, and the previous statement is true, doesn't that whole circuit of travel ending up back at "point A" describe the type of journey one would make traversing the length of a Mobius strip? Thus, are 'branes really 2 dimensions of the 11 theorized or are they 3 dimensional Mobius strips where, if a 'brane were a 2D square with corners A, B, C and D, clockwise from top left, and corners A & C and B & D were joined (and thus the sides AB and CD joined)? BTW, this also begs the question, "What about travel ACROSS the strip?" Does one "fall off the edge or walk onto a parallel strip? Or is travel (read: Motion) actually only possible in only one dimension in both the positive and negative directions (i.e. going "forwards" and "backwards" on the strip)?