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[Glowcat]

Speaking of FTL... anyone see this yet?

http://www.space.com/17628-warp-drive-possible-interstellar-spaceflight.html

*breathes deep*

Pleaseberealpleaseberealpleaseberealpleasebereal

[MaximumZero]

Yeah, there's a little conversation going in the Higgs thread.

[Starver]

Back to the original question (hey!  another Relativity/Time Travel/etc derail!), if there was FTL capability but I didn't yet have a hold of the means myself, I would...

...periodically stare into the sky, and grin.  In the knowledge that it's possible I could later (when I do have FTL capability) go out beyond my own light-cone, point a camera backwards and take a snapshot of myself.  (And while the resolution might not be brilliant, I can keep on repeating that, from slightly different angles until I've built up a decent image, whilesoever I've not totally captured every single photon that scattered off my ugly mug and hasn't hit something else yet.  And, presumably, I shall also be able to amass increasingly sophisticated camera equipment and processing power to work with what images I capture.)  Essentially Picard Manoeuvre myself, oh yeah...

And, I've just realised, that's about the most self-centred thing I've ever wanted to use science for.  It's also occured to me that I can speculatively grin into space even now, before FTL is actualised, just speculatively for when we can.  Also, it's not inconceivable that I shall at one point appear on Google Maps.

(Right, disappearing back into my shell now...)

[mainiac]

the important thing is that you are subluminal in your local space.

Yeah you don't violate causality in your local space.  But if you fly away at ftl then turn off the drive and fly back at sub-light speed you just violated causality at the place you started by arriving before you left.

[Starver]

the important thing is that you are subluminal in your local space.

Yeah you don't violate causality in your local space.  But if you fly away at ftl then turn off the drive and fly back at sub-light speed you just violated causality at the place you started by arriving before you left.

In the manner you just wrote that, no you don't.  Taking two simply separated points as start and (intermediate) destination points, you will jump, via FTL to the other point and your (for now, assumed immediate) arrival there will be seen after the normal delay of light between that location and your origin, and if you then follow on by returning at sublight speeds you won't 'happen' to the place you started from until some additional time after the moment you departed.

The problem with causality comes more from departing at FTL from one point and returning again by FTL from a second point where the two points are actually in different frames of reference, and have different ideas of where(/when)abouts in their respective histories the other is, as far as the assumed instantaneous transit method is concerned.  'Mere' lightspeed communication or sublight transition on one leg rather delays your return/influence until after it would have been "prior" to your leaving, if I've not forgotten something, although I've got to work my head around a very high relativistic difference in frames...

(The problem of relative frames might be solved by assuming that arrival at position B sets you into a consistent frame to the one you left at A, and that you need to do some work to then become 'one' with B's actual frame, for the purposes of adopting the intermediate frame's POV of A that would give you that paradox.  Either that or you 'curve' between frames, in a exactly reversible manner if you had two instantaneous travels, with zero waiting time at the far way-point.  But that's just off the top of my head, and is open to criticism.)

[Eagleon]

I'm probably one of the few people who would try to apply the FTL principles to a computer system. Even if the only application would be to make data move faster, I'd imagine that would still give a decent boost to computer speeds. Alternately, you could have a hyper-fast coolant flow that could handle massively overclocked CPUs.

This, in a nutshell, is arguably more important than breeding across the galaxy if causality-breaking FTL is possible. With it you can have computers that process their instructions instantaneously - the only limitation is the volume of memory you can accumulate. But that would also mean that we're boned if someone doesn't use a language with recursion checking - we'd be doomed to spend the same microseconds for eternity, or until the computer underwent critical existence failure. Time travel is creepy as hell, if you think about it too much.

I don't see how breaking causality by going faster than light would be the same as time travel, anyway.

Time is the fastest thing in the universe, but it doesn't really travel at infinite speed. If you travel at superluminal speed, yes, you can outpace the light output from the supernova and probably tell someone far, far away, 'hey, look over here at such and such time and you'll see this awesome supernova' but if you turn around and go back, even superluminally, you won't suddenly pop up at the supernova before it happened.

It's not that simple. By going at c, from your own perspective you're traveling at infinite speed. Everything else (including light, since it slows down outside of vacuum, which doesn't exist) is frozen, in the truest sense that if you move, you're watching the progression of the universe on a cosmological (c, hehe) scale. By going faster, causality is instantly violated, because things can't get more frozen than they were before - they're forced to go backwards. Your observing that makes the outcome different, unless you aren't observing it at all. That's why tachyons, if they do exist, would never be observable - the alternative is that any interaction, no matter how minute, would change the outcome of events in impossible to predict ways.

That's all time travel really is - reaction not following the actions they're supposed to. FTL without warps in space does this, over immense macroscopic periods. It's why even a tiny violation of causality is probably impossible, because how do you reverse the laws of physics if they're based on probability? What is there that exists to facilitate your time machine going against the grain? It's more likely that there's some loophole to completely destroy the universe than there is to go back in time in our own physical dimensions (only maybe if there are others), because as far as we know there's no reason for it to work that way at all.

At least that's how I was given to understand it.

[Scoops Novel]

Please, outline the Bay12 space program for me.

[Jelle]

Hijack one of these FTL thingamajings and get as far away from the rest of humanity as possible on a habitable planet. Possibly take along a group of people I deem deserve better then humanity on earth can offer and build a new, better world on said planet.

[werty892]

You realize your threads are taking up 30% of the front page? STOP MAKING THREADS -_-

As for FTL, I would join a ship, start a mutiny, and become a spehss pirate

[Scoops Novel]

It's an old thread, so... .

[SalmonGod]

You know... the more I read about relativity/time travel relating to light speeds, the more it doesn't make sense to me.  The whole thing seems to hinge on the idea that light, as the upward limiter of our frame of reference for the flow of time, is synonymous with time itself.  I don't see why reality should become fucked up just because we're unable to accurately perceive an event.

I know I'm probably missing some major component of the theory here... I've never actually studied it, just spectated many conversations such as this one.

[10ebbor10]

You know... the more I read about relativity/time travel relating to light speeds, the more it doesn't make sense to me.  The whole thing seems to hinge on the idea that light, as the upward limiter of our frame of reference for the flow of time, is synonymous with time itself.  I don't see why reality should become fucked up just because we're unable to accurately perceive an event.

I know I'm probably missing some major component of the theory here... I've never actually studied it, just spectated many conversations such as this one.

The point you're missing is that humans haven't really evolved to deal with this sort of stuff. It relies on strange for of mechanics and such.

As for time= light. It's not like that. There's however, something as time dilation, meaning that the faster something goes; the slower the time goes for that object as seen through an outside observer. So if you launch a clock at lightspeed, it would appear to stand still from the point of someone observing it. This means that if theoretically you were to faster than time, time inside the spaceship(and actually; the whole spaceship itself) would go back.

This is also why going FTL without exceeding the speed of light (by cheating using a warp drive for example) doesn't cause any of these problems.

[TheBronzePickle]

The thing about going lightspeed is that you aren't magically frozen in time. You might look back and see a frozen universe behind you, but if you look forward than time is advancing twice as fast, because the light itself is traveling twice as fast towards you. Once you stop at your destination, you'll be able to look back and see your start the same as when you left off, but if you turned around and went back at light speed, you'd end up returning to 'real time' in that sector after seeing a sped-up version of the events that transpired.

[10ebbor10]

The thing about going lightspeed is that you aren't magically frozen in time. You might look back and see a frozen universe behind you, but if you look forward than time is advancing twice as fast, because the light itself is traveling twice as fast towards you. Once you stop at your destination, you'll be able to look back and see your start the same as when you left off, but if you turned around and went back at light speed, you'd end up returning to 'real time' in that sector after seeing a sped-up version of the events that transpired.

No it's not.

You're getting the entire idea of time dilation wrong. The faster you go the slower time actually moves for you. Science fact.
See the clock experiment for more information.

Spoiler: Short recap (click to show/hide)

2 clocks; 1 on a plane.
Plane clock flies tours around the Earth, other stands still. When they meet up again the plane clock is running a few microseconds behind.

At lightspeed(which is impossible to get), and according to current theories you would indeed be "magically" frozen in time.

[kaijyuu]

If you go the speed of light, you arrive at your destination instantaneously (from your own perspective), and ALSO the time it takes to travel there at the speed of light (from everyone else's perspective). According to the light that enters your eyes when looking at the stars, the time it took to reach you was 0.



Anyway, going faster than the speed of light won't send you backwards in time; it sends you into imaginary time (square root of negative 1 type of imaginary). Don't ask me how that works.