What is it with the speed of light, causality & time travel?

[Strider]

You can't have FTL and avoid causality violations without breaking Relativity in some manner. Nothing Strider mentioned applies in a Universe with a fixed frame.

Do remember, any universe with a fixed frame of reference has no relativity at all. A fixed frame of reference invalidates the Special Theory of Relativity completely and utterly and results in an entirely Newtonian universe.

[Darth Raptor]

I don't know about you guys, but I'm thoroughly impressed by Bubble Boy's belligerent demolition of arguments no one was making. I'm on the verge of swooning from that masterful display of self-pwnage.

[Singular Intellect]

I don't know about you guys, but I'm thoroughly impressed by Bubble Boy's belligerent demolition of arguments no one was making.

Apollonius referenced 'god' as some type of explanation when that clearly isn't the case, and I pointed that out. He also claimed 'experts don't like to speculate' and have to be 'encouraged to do so by laypersons', a rather irritating insult, intented or not.

He ended up defending his position by pointing out he took the arguement in the context of fantasy and science fiction, which obviously isn't the stance of SLAM. Which I pointed out in my PM to him, having agreed it was getting off topic.

So unless you think the idea of god has any relevence to science, logic or morality, kindly grow a fucking brain.

I'm on the verge of swooning from that masterful display of self-pwnage.

You mean you lack reading comprehension skills; pretty fucking obvious.

[madd0ct0r]

Aw Bubbleboy, you remind me of a pit bull in a toyshop.


back to the science fiction universe that does not have to match ours (especially if the plot requires it - FTL getting you to next weeks exciting episode!)

What exactly do people mean by universal frames of reference?
I'm kinda picturing a giant beacon (well, ice cream cone but I'm hungry) floating in either deep space or at a Lagrange point that pulses out an irrational number.
In order to know when you are you need to know the full length (or as many digits as are expected to be used before the universe ends, which isn't as bad) of the irrational number and compare it to the current pulse.


There was also another method of space travel i encountered somewhere that involved cosmic strings. you 'scrunched' your strings up very tight, making your atoms relatively (bad word) larger and less dense. Gone far enough you could set across the galaxy and then let the strings go back to normal. Apart from the obvious, I also wondered whether changing the your nature of matter like that would not affect how time flows for you too?

[Ariphaos]

Do remember, any universe with a fixed frame of reference has no relativity at all. A fixed frame of reference invalidates the Special Theory of Relativity completely and utterly and results in an entirely Newtonian universe.

Only a purely Euclidean frame would cause that, and I'm not sure you could get that to match our Universe anyway. I mentioned that caveat right off - a Universal frame obviously cannot be visible through (normal) subluminal or luminal means in a relativistic Universe like ours. It certainly does not have to result in an entirely Newtonian Universe.

What exactly do people mean by universal frames of reference?
I'm kinda picturing a giant beacon (well, ice cream cone but I'm hungry) floating in either deep space or at a Lagrange point that pulses out an irrational number.
In order to know when you are you need to know the full length (or as many digits as are expected to be used before the universe ends, which isn't as bad) of the irrational number and compare it to the current pulse.

As Strider sort of points out, a universal frame cannot actually exist within our Universe, at least not in any way that I've been able to conceptualize. It may be more appropriate to state that the universe is a phenomenon that would exist in whatever larger structure of laws that make up the universal frame and not the other way around.

It's easy to show why. Someone moving at .86 of c with respect to you experiences time half as fast. And, likewise, you experience time half as fast as they do, from their perspective. Inside a fixed frame that is fixed at a point inside of our Universe, that means one of those progressions of time is more accurate than another.

Which leads to an absurdity beyond the local (galactic) scale - the majority of the Universe is receding at FTL speeds from any given point within the Universe. You run into that no matter what point within the Universe you choose.

Saying "100 times c" - or any number greater than 1 - without specifying the frame automatically slams into the above absurdity if you're trying to maintain causality.

If the Universe is the surface of a hypersphere, however, the center can become the special frame without running into the above problem. I believe this is what the Culture uses - successive pulses from a 'hypercenter' create shells of alternating universes of matter and of pure energy, and fix the frame, thus disallowing time travel.

That's the only one I'm capable of explaining in any sort of detail. A hypersphere is probably not necessary and possibly entirely inappropriate, but you need to account for the expansion of space.

There was also another method of space travel i encountered somewhere that involved cosmic strings. you 'scrunched' your strings up very tight, making your atoms relatively (bad word) larger and less dense. Gone far enough you could set across the galaxy and then let the strings go back to normal. Apart from the obvious, I also wondered whether changing the your nature of matter like that would not affect how time flows for you too?

Explaining how faster than light travel works in any given universe is a test of an author's scientific bullshitting skill. They obviously failed.

Anyway, yes. The denser you make a piece of matter the more effect it has on the progression of time for its immediate surroundings. So you make yourself roughly the size of an atomic nucleus and 'normal' people seem to be moving a whole hell of a lot faster than you.