May I say that so little is known about the dimension of time and space that what Dr Greene said is as basic as it can get. I certainly understand his theory but I doubt that it will be done that way. Einstein believed that all time exists all the time. Thus the future already exists? What happens to non determinism then? If the E 8 lattice is the basic construct and this reality is a projection then perhaps traveling dimensionally may be the answer. I don't have the answer but neither does anyone else at the moment.
RE: Time travel is possible