String theory originally was ten dimensional until M theory was discovered that found that all the five string theory possibilities could be seen as the same thing in the eleventh dimension. If we go on to the twelfth dimension we get F theory that has the inconvenience of generating two orthogonal time lines. Personally I find the idea of orthogonal time lines intriguing as it goes back to Dunne who in his book An Experiment in Time and Serial Universe postulated that time was multidimension. This idea was taken up and explored by Tolkien and appears in Lord of the Rings as the different temporal experiences of the various members of the fellowship. Seems in the fourteenth dimension there are three orthogonal time lines, and I have not found reference to it but I am betting that there are four orthogonal time lines in the sixteenth dimension. I call this multiplication of orthogonal time lines heterochronic. It is one route to finally putting an end to Metaphysics.
Quora answer: Why there’s a need for 11 dimensions in a string theory?