1-Way Time Travel.

[Starwhip]

So here's an interesting fact. At 0.9999999 % the speed of light, over a distance of 42 light years, it takes just over 42 years for someone watching you to see you land. But it takes you 4.8 hours to get there. You are offset in time by quite a large amount. Now, this is assuming you can accelerate instantaneously to that speed and just as instantaneously decelerate. But it demonstrates this thing called "Time Dilation". And I figured out that if you did go at the speed of light, time for you would literally stop. Zip, nada, zero. So you would be stuck forever at the speed of light, since any ship computers would also be going at the speed of light and would stop. In layman's terms: You're screwed.

This could be used as time travel. Since time is entirely relative, you would only age 4.8 hours every 42 years at this speed. And this is exponential. The closer and closer you get to lightspeed the slower you age.

[shynung]

In theory, it works. Indeed, we could travel to thousands of years into the future this way.

But first, we have to solve the problem of accelerating to 0.9999999c without killing ourselves on the way. Enormous fuel and propellant requirements are also an issue, but that's just an engineering problem.

[Starwhip]

I envision the popular motto: "Add moar boosters".... and something that looks like it came out from under Whackjob's bed.

Bussard Ramjet, anyone?

[Skyler4856]

The lorentz factor, and time dilation are common knowledge throughout the forums.

[WestAir]

That's why the speed of light is better for us than FTL travel. At 2x the speed of light it will take forever to get anywhere, but with the limit of C, we can travel to distant galaxies in hours with proper (unrealistic, but that's beside the point) acceleration.

[Brotoro]

So here's an interesting fact. At 0.9999999 % the speed of light, over a distance of 42 light years, it takes just over 42 years for someone watching you to see you land. But it takes you 4.8 hours to get there. You are offset in time by quite a large amount. Now, this is assuming you can accelerate instantaneously to that speed and just as instantaneously decelerate. But it demonstrates this thing called "Time Dilation". And I figured out that if you did go at the speed of light, time for you would literally stop. Zip, nada, zero. So you would be stuck forever at the speed of light, since any ship computers would also be going at the speed of light and would stop. In layman's terms: You're screwed.

This could be used as time travel. Since time is entirely relative, you would only age 4.8 hours every 42 years at this speed. And this is exponential. The closer and closer you get to lightspeed the slower you age.

Wouldn't it take just over 84 years for someone at my starting point to see me land? It's going to take just over 42 years for me to get there (in their frame of reference)...and then another 42 years for the light showing me landing to reach home base.

[Spica]

-snip-

What was the formula you used to find the specific amount of time dilation for a given speed?Nevermind.

Edited March 31, 2014 by Spica

[Scotius]

Y'know, we are travelling in time. Forward. Second by second

[Sillychris]

I know this isn't entirely on topic, but isn't the Kerbal universe entirely non-relativistic?

[KerbMav]

That's why the speed of light is better for us than FTL travel. At 2x the speed of light it will take forever to get anywhere, but with the limit of C, we can travel to distant galaxies in hours with proper (unrealistic, but that's beside the point) acceleration.

Know we cannot - how? If we are not going faster then light, then how ...

Oh, you mean it will take hours subjectively when flying at almost c in normal space opposed to travel months and years through subspace or something!

I know this isn't entirely on topic, but isn't the Kerbal universe entirely non-relativistic?

You know what I love?

People not throwing an assumption or theory into a texted message/forum post without delivering some further thoughts why they actually think that way.

Edited April 1, 2014 by KerbMav

[MKI]

Biggest thing about trying to think of things working at the speed of light is NOTHING works at the speed of light because its NOT POSSIBLE in the first place.

You need infinite energy to get to be AT the speed of light. You can get close, but its impossible to cross it.

There's always those shortcuts such as bending space to "move" faster than light, as space can expand and contract as much as it wants. But nothing is actually moving at the speed of light, only the space around you is.

Im more of a fan of bending space, rather than trying to chase the limit of all moving things, and if you think about it time itself

[Padishar]

And I figured out that if you did go at the speed of light, time for you would literally stop. Zip, nada, zero. So you would be stuck forever at the speed of light, since any ship computers would also be going at the speed of light and would stop. In layman's terms: You're screwed.

This is not true. Your time does not slow down as you travel faster. Your time as seen by an outside observer slows down but this is not the same thing. Relativity, while logically consistent and backed up by experiments to a very high accuracy, is not intuitive and the usual descriptions of time dilation effects usually only introduce further misunderstandings. However, the standard twins paradox is true, if one twin leaves on a fast ship and returns many years later then the twin that stayed home will be much older than the one that went and this can effectively be used to travel into the future "faster" than you would normally.

Another example is when approaching and crossing the event horizon of a black hole. As you approach the event horizon (carrying a clock that can be seen by an external observer), your clock will appear to that observer to run slower and slower until, at the point you cross the event horizon, your clock (and you) would appear to freeze. As far as you are concerned you would not notice any odd time effects at all and would, with a sufficiently massive black hole (where the event horizon is many light years across) continue to travel towards the singularity with no ill effects (until the tidal gravitational forces stretch/squash you into nothing).

[Piscator]

Just for curiosity's sake, could someone please double-check the original claim? My own calculations arrive at little under a week of perceived flight time for the given speed and distance (you would have to fly at about 0.9999999999c to make it in 5 hours). Am I doing it wrong or aren't the figures in the OP supposed to be a 100% accurate?

[GreatWyrmGold]

Know we cannot - how? If we are not going faster then light, then how ...

Oh, you mean it will take hours subjectively when flying at almost c in normal space opposed to travel months and years through subspace or something!

Unless it takes only hours to go through subspace.

Or unless it takes absurd amounts of resources to reach near-luminal speeds.

[Sillychris]

You know what I love?

People not throwing an assumption or theory into a texted message/forum post without delivering some further thoughts why they actually think that way.

Ok, here's why I think that the Kerbal universe isn't relativistic: There are many claims of people exceeding the speed of light in KSP using infinite fuel. I am also aware that the physics engine is strictly Newtonian, so your mass doesn't increase with Kinetic energy.

I have messed with infinite fuel a bit and gotten to relativistic speeds and I have noticed no lorentz contractions.

Satisfied?