Relative Time Travel

Toxic

New member
I was watching the Star Trek reboot at way too late an hour last night/the next morning, and I guess the prompted my mind to think about things in that really purpose? Anyway, random situation/question.

Imagine you've got an astronaut. This brave explorer of the cosmos goes on a brief shuttle trip up to a satellite and back again. Then, a half-year later, the government sends him on an epic exploration mission to a planet exactly one light year away. The valiant spaceman makes the trip at a rate of twice the speed of light, arriving at the planet exactly a half year after he left earth, or one year after his satellite mission. Arriving on the planet, the astronaut pulls out a really good telescope, and knowing exactly where earth is in respect to his current location, looks at it through the telescope. Gazing at the space around earth, he can see his own spaceship, and him in it, docking with the satellite he ventured to a year ago.

See, the light from that entire incident would take exactly one year to reach his location on the distant planet, and since he traveled at twice the speed of it, he caught up with the image of himself at the satellite. Would this not imply then, that in relation to earth and the satellite, he's traveled back in time exactly one year?

But what if he traveled at the speed of light, instead of twice the speed of it. In that case he would travel for a year and see an image of his craft taking off for his journey to the planet he just landed on. Still on year back in time.

If he traveled at half the speed of light? The trip would take two years, and he'd see what the earth looked like a year after he left. Still traveling back in time one year.

What I'm getting to here probably doesn't even make sense, but would that not imply that as we move away from objects, we travel back in time in relation to the distance we travel away from them? Similarly, that as we move towards objects, we move forward in time in relation to that object?

It may not be possible to interact with the past and future at a tangible level, but from an observers standpoint would that not make travel back and forth through time entirely possible? Hell, just moving your head closer to and further away from your computer would be a trip back and forth through time. An inconceivably small trip, but a trip nonetheless?

Anyway, I'm probably seriously overthinking everything. I blame science fiction.
 
That's not time travel. It's just a residual artifact of the speed of light and interstellar distance. Moving further from events at (theoretically impossible) velocities of > c does not mean you've traveled backwards in time. We see this every day when looking to the stars. If you look through a telescope at the Andromeda Galaxy, 2.2m light years away, you're not seeing how it looks now, but rather how it looked, 2.2m years ago. It's a useful scientific phenomena to studying previous stages of the observable universe (and partially the reason why we were able to detect the Cosmic Microwave Background).

You're always time-traveling, however. Traveling into the future second by second. As much as movies and books talk about it, I don't see how time travel could actually be possible. The only instances where you could possibly infer a cause happening after an effect are in instances of simultaneity when theoretically dealing with two frames of reference moving at significant fractions of c.
 
Top