How to travel through time and what you can do with it.
To travel at the speed of light or even faster than the speed of light is very hard, but very simple at the same time. First you need to get a fixed point in space and put a weight there. Then on the weight attach an infinitely stiff rod about 2-3 AU’s in distance (an AU being an Astronomical unit, the standard unit of measure from earth to the sun so about 20 million miles) then a few thousand miles out from the center point put an open sided particle accelerator so the rod can move very quickly.
Then you turn the accelerator on then the rod will move very fast near the end because of the way it moves in a circular motion. The reason for the fixed point is the law that the center of a wheel moves exponentially slower than the outside of the wheel. This set up allows the near center of the rod to travel at thousands of miles a second and the further out you travel from the fixed point along the rod the faster is moves. Thus giving you the speed necessary for faster than light travel which could never be reached by conventional means.
A neat experiment that you could try is putting an atomic clock at the center of the rod, where the rod is just before light speed, at speed and faster than speed. Assuming that Einstein was correct with his theory of relativity the clock before speed should move very slowly, the one at speed should stop and the one faster than speed should be going backwards. You then also do the same thing with a chemical reaction or particle decay experiments.
You could also theoretically travel forwards and backwards in time using the machine. But the entire experiment depends upon the fact that the rod be very long and infinitely stiff. This allows the center of the rod to move very fast and the other end doesn’t bend or twist with the stress of acceleration. But since you could never really get something infinitely stiff this experiment would be impossible to do in real life.