Time travel?

We're all traveling through time, sort of. It's not that great though because we all travel through time at the same rate, at one second per second. The trick then is to travel at more than one second per second, or less, or even travel at negative one second per second. Fortunately, help is at hand because time travel is in fact possible, according to the laws of General Relativity anyway. Unfortunately, it doesn't involve a simple and cheap flux capacitor dissipating 1.21 GW. You need gravity, because you have to severely distort spacetime. In essence, there are two ways of making a time machine and both of them involve a singularity. A singularity is the sort of thing you get in the center of a black hole. It is a point, line or sheet of infinite density. When very massive stars die they sometimes collapse into a singularity, which is almost always obscured by the event horizon of a black hole. However there is no law that says they have to be hidden from view. But I digress.
When some matter collapses into a singularity it forms, for a very brief instant, a wormhole to another region of spacetime, in this universe or, more controversially, another universe entirely. The wormhole immediately pinches off though, but there is a way around that. What you need is some exotic matter, which is predicted to be left over from the big bang. No such matter has ever been found but in time with space exploration perhaps we might find some. What we need is cosmic string. Cosmic string possesses a peculiar property called negative pressure, which we can use to keep the wormhole open. Once we have created a wormhole, and located the other end, we must then move one mouth of the wormhole around at very high speed (I think you can see how difficult this is going to be) so that time slows down for it. Moving clocks run slow, so time slows down for moving wormhole mouths. We need to move it around fast enough for long enough to create and appreciable time difference between the two mouths. Then all we have to do is bring the two mouths together. If you travel from the mouth that moved to the mouth that remained stationary you will effectively travel into the future, whereas if you travel in the other direction, you will travel backwards in time. You can never travel backwards in time earlier than the creation of the wormhole though.
The second way to make a time machine is to take some neutron stars, ten will do, and spin them up really really fast. So fast that at the surface the instantaneous velocity is about half the speed of light. Then you need to align them all so they're pole to pole and they will collapse into a spindle singularity. At this point you may travel through time using the spinning singularity. It works because a rotating mass drags spacetime around with it, in theory. The earth does this too but you don't notice the effect because the earth is rotating very very slowly, and it is extremely light. But it's real, according to Einstein, and data is now available to confirm or refute it. The data is still being analysed, but it's assumed that it will be right. Anyway, in the region around a very quickly spinning, very heavy singularity, the effect is so strong that time and space start to interchange, so you can travel in a closed orbit around the equator of the singularity to travel forwards in time, or in the reverse direction to travel backwards in time. Again, you can only travel back to the moment is was created, but hey, it's time travel, and there's nothing that says you can't do it.