# Are there formulae for non-FTL starship speeds and and relative time passed? [closed]

I'm about to run a sci-fi campaign with sublight starship travel, with a solar system and to all the stars within 10 light years of Sol.

There are starships that accelerate at 1g, and some that accelerate at 2g, and they can change the acceleration rate a bit for comfort.

Given that I have variable acceleration rates, and variable distances, I need: A formula for how long the passengers think it takes to travel X parsecs under Y acceleration. A formula for how long an outsider thinks it takes the passengers to travel X parsecs under Y acceleration.

## closed as off-topic by user14111, phantom42, Izkata, The Fallen, Joe L.Oct 1 '14 at 1:35

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• "Questions seeking scientific solutions or explanations are off-topic unless they relate directly to a cited work of fiction. There are a number of other Stack Exchange sites dedicated to answering questions on non-fictional sciences." – user14111, phantom42, Izkata, The Fallen, Joe L.
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• So, you want to incorporate relativistic time dilation? – user1027 Oct 1 '14 at 1:06
• There's a lot of theoretical info on what happens as an object accelerates to near-lightspeed, but I've never heard a good explanation for what happens when a relatavistic object slows down. – Joe L. Oct 1 '14 at 1:31
• See How long would it take me to travel to a distant star? on the Physics SE – John Rennie Oct 1 '14 at 8:24