Does time dilatation make travelling close to the speed of light redundant?
I find time dilation confusing so I'm not sure if it is a relevant factor.
Lets say you have a spaceship. There's no such thing as faster than light travel, but you do have inertial dampener technology that allows you to accelerate at very high G's without obliterating yourself.
You want to get to a nearby star system as soon as possible. When I say "soon" I mean early on the timeline of the destination star system, not necessarily as quick as possible according to your own perspective of the voyage duration. In other words, you want to intervene in the events of the destination before they progress to far into the future.
Is there a maximum rate of acceleration or top speed you could reach before time dilatation causes you to actually arrive later than you would have at a lower speed?
What about if you want to go there and then get back before your friends at home get any older?
This post was sourced from https://worldbuilding.stackexchange.com/q/90731. It is licensed under CC BY-SA 3.0.
1 answer
You cannot get there faster than light (from the perspective of the places you are traveling from and to, if they are [nearly] at rest with respect to each other (meaning even if they are both moving, the distance between them is not increasing or decreasing by more than a few miles per second).
If they are 10 LY apart, it takes ten years of their time for a signal (or anything within a few percent of the speed of light) to move between them.
This also means you cannot know what is happening on B if you are sitting on A, and vice versa. No kind of signal known to physics, not even a gravity wave, travels faster than light. If a revolution occurs on B, the people on A won't hear about it for ten years. Then it would take them at least ten years to get there and respond.
Now, traveling at near light speed (say 99.99% and they have an unlimited energy supply to do it) the amount of time that passes for the passengers is contracted by a factor 70.71. So 10 years, or 3650 days, the passengers, ship and everything in it will only age 51.6 days. (This is not a "feels like" but actual time passage.)
Also note that when they arrive at B, it will have been 20 years since the message about the revolution was first sent. (They may know more about what happened in that 20 years by capturing signals from B along the way there, so they may be up to speed when they land.)
0 comment threads
0 comment threads