Traveling back in time is not possible in the physical sence. I think God made it an illusion for a good reason. The paradoxes just don't make it plausable. Of course you can move through time in a spiritual sence. Looking at it from the highest source, there is no past and no future, everything happens in one moment. You can make time slow down or speed up from your perspective. But physically you can not travel backwards. Or at least that's what makes sense to me.