That’s not time travel, that is time dilation.
The faster the vessel you are on gets to light speed, the less time (subjective) it is for you. However, time still goes on the same in the regular universe.
For example, imagine a spaceship traveling at 95% of the speed of light to a planet 9.5 light-years away. A stationary observer on Earth would measure the journey time as distance divided by speed, or 9.5/0.95 = 10 years. The spaceship crewmembers, on the other hand, experience time dilation and thus perceive the trip as taking only 3.12 years. (The math here is a little more complicated, but we’ll get to it later.) In other words, between leaving Earth and reaching their destination, the crewmembers age a little over three years, while 10 years have passed for people back on Earth.
> That’s not time travel, that is time dilation. <
Right! I call it “time travel” to keep it in layman’s terms. But as you noted, the proper scientific term is “time dilation”. It’s all about who the observer is, and how he is moving relative to the object.
If there is no acceleration, each will think the other is time-travelling!