It depends on what you concider time travel. For me to concider a something time travel I must be able to interact in the different time. Just watching time speed up or slow down i not time travel at all to me. Most people(as in those that I have known) concider light as a sufficient conveyor of time passage. I concider time as a constant, with a value if infinity. Everything that we see is delayed by the speed of objects in relation to each other in relation to the speed of light at the time interval. If a hypothetical spaceship was traveling at near the speed of light directly away from an object the ship would see the object as almost frozen in time, and time in front of the ship would be nearly 2x actual. If the ship momentarily attained a velocity higher than that of light, if it slowed to just under tthe speed of light the object behind it would be in a time period previous to the ship's velocity surpassing that of light. Most people would concider that a shift in time-space. I don't concider that a time-space shift be cause the actual speed of passing time has not changed. I see people yelling at one another abou time, and most of the time they are both right. Their definition of time travel is the only thing that isn different. I occasoinally hear people talking about people talking about worm hole and saying that the object can reach the other end before it enters the begining. They concider relativity as a way of actually altering time flow, relativity does not change the passage of time; only light(or the time measurement in question).

I am not saying that you or anyone that reads this has that belief. It was mostly me just typing away, the first couple of sentences pertained to your post. Some of the rest may have also pertained to your post, but please don't take anything as against you.

I would like to know your definition of time travel.

Thanks for your time.