Well firstly time dilation? Time is always constant and is not effected by an object in vacuum approaching and exceeding the speed of light. There is no resistance or drag effect in a vacuum zero g environment.
You need to brush up on your Minkowsky spacetime knowledge. Then, read up on general and special relativity. Time is not always constant, it is relative to the slope of spacetime, which likewise is relative to length contraction and there is a relationship between all of those.
Time is constant within your frame of reference, but your frame is just that, a frame, thus surrounding regions of space may have time progress slower or faster relative to their slope.
This is complicated stuff, be sure, and nigh impossible to understand unless you comprehend the underlying laws and theory within physics.