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[Cy83r]

hehe, I really hope Dec 21, 2012 doesn't happen. Looking forward to seeing what is coming next.

You... you disappoint me.

[NOMAD]

how so

[Mjolnir]

A lot of people seem to forget that science only ever says "this is good enough for now" not "this is it, forever, period".

So, in conclusion: dammit, let me think we at least have a chance at it until the hard numbers get back in the next several decades! Psychic powers have been dead and buried for almost the last two decades, don't take away my FTL drives just yet, we aren't even on Mars.

Exactly, as long as there´s no "terminal" or "concluding" world formula, there´s still a lot to discover. On (nearly) every field.

But nothing as yet undiscovered can make FTL and causality compatible. A complete description of the universe isn't needed for this to be determined. It doesn't matter that we don't know in detail how a particular FTL phenomenon will behave, the fact that it is FTL together with the existence of time dilation is enough. It doesn't matter that we don't have any solid descriptions of the effects of wormholes or tachyonic particles or some hypothetical hyperspace, only the end result matters.

There is no need to wait decades for further "hard numbers"...time dilation is not speculative theory. Relativistic effects are verifiable with atomic clocks that now cost a couple thousand dollars (a couple hundred if you can do it with a decent rubidium clock). Global simultaneity doesn't exist, and signals propagating faster than c...regardless of the means...can return to their origin point before they were sent. It's not some subtle issue involving a poorly-understood intersection of thermodynamics, quantum mechanics, and relativity as the black hole information loss debate was.

Observers taking different paths through spacetime can experience different amounts of time before meeting again. This is measurable, repeatable fact. Simultaneity can therefore only be defined locally. Observers in different frames will have different conceptions of "now": person A at time 1.0 can see person B at time 0.5 as being in their present, while person B at time 0.5 sees person A at time 0.0 as being in their present. Lightspeed lag is what prevents messages from reaching the sender's past. FTL travel and time travel are the same thing.

[junk]

To be honest as far as I understand the light speed barrier is an acceleration barrier. There have already been particles observed at moving multipliers of the speed of the light for instance. Photons in nano sized tunnels.
Also if you be capable of reaching ligth or supra light speeds without requiring acceleration you could actually continue moving at those speeds. Since the issue is an increase of mass to limit infinite. Get speed over light and your mass flips over to negatives.

Another options would be to find a way to somehow negate all mass of the ship and and everything in it. Once more a way to get past the = mass increases to inifinity issue.

Basically these two methods would allow you to reach FTL in conventional space.

As to the reasoning of there being no FTL possibility due to the lack of FTL travelers feels somewhat wrong. The galaxy is big enough that even if there were a couple of FTL cultures they could easily not come across each other.

Likewise while stealth in space is kinda an oxymoron, the area is vast enough, that we would potentially not register the heat output of a spaceship in the Sol system.

As to causality - I admit I've never heard of FTL impacting causality. You can potentially argue that you can time travel forward via FTL or even near light speed due to a slower flow of time for the people traveling, but never heard of travel into the past.

A good example of this time flow forward is the foreever war.

Aka never heard of a signal reaching it's point of origin before it was transmitted. But I've heard of a signal spending less time traveling than time has passed at the point of origin and destination.

Of course it's been a couple of years since my last physics class.

[dfacto]

Yes, FTL leads to apparent causality violations. Google it, there's lots of discussion on it.

What I want to know is if that even matter? Perhaps causality violations aren't actually relevant at all, as time and its perception may only be relevant to us and our biology.

Or maybe causality violations lead to a big BSOD.

[Razor One]

I'll try to put this into laypersons terms as much as possible.

Space and time are linked.

Movement through space is also movement through time and vice versa, movement through time is also movement through space.

This is true as all motion, all space and all time is relative. You can never truly be at a standstill except as defined relative to something else. You are only in a certain section of space as relative to all other sections of space and you only occupy a certain amount of time as relative to all other amounts of time.

Relativity shows us that the faster you move through space, the slower you move through time. The closer you approach the speed of light, the more time slows down.

To attain the speed of light, you would need infinite energy. The universe is a finite system despite its enormity. There is only so much energy and mass. Therefore, even if you were to gather all the energy and mass in the universe and utilise it towards accelerating towards C, you would still come up hopelessly short.

FTL and Causality are a huge problem for physicists. You can have one, the other but not both. Relativity is non-negotiable at this point.

To understand the conundrum, let us examine causality.

Causality generally goes from Cause to Effect.

Cause = I stub my toe.
Effect = I feel pain.

The existence of FTL would throw out the concept of cause and effect. Causality would be forever broken. This would allow a universe in which I could feel pain before ever stubbing my toe. What happens if I never stub my toe as a result of feeling the pain before it happened? Paradox.

Buy why does FTL break causality like a two dollar ming vase?

Remember back at the beginning when I stated that movement through space is movement through time? Ditto for anything going FTL. Going FTL means you're travelling backwards through time relative to an observer.

You could do a round trip and arrive before you left. Just being there messes with reality's mojo. Even if you catch yourself arriving before you leave and leave to preserve the flow of events... did you leave because you wanted to or did you leave becasue you arrived before you left? That's a paradox. The universe doesn't like paradoxes. It's allergic to them. Trust me on this, the universe and I are on pretty good terms with each other. Usually.

As for photons exceeding the speed of light, Recently disproven.

Now...

How does this vaguely relate to Outsider?

FTL and Causality can be possible under certain conditions... if you toss out relativity.

My mind is a bit fuzzy at the moment, but here goes.

Relativity basically postulates that there is no one 'special' place in the universe. One location is much like any other, and each location is relative to one another.

If you toss out relativity though, you can have special places of reference that would allow you theoretically to exceed the speed of light.

In the outsider 'verse, this region would be called Hyperspace.

If we assume that Hyperspace is a special reference frame for the rest of the universe at large, than we can have paradox free FTL.

The way we can break it down is like so.

Alex fires an FTL bullet at Fireblade (who will kill Alex should she survive). Being FTL, the bullet must take on the special reference frame.

Beryl sees Fireblade being shot by the bullet before Alex could logically have fired it and sends an FTL signal to Stillstorm to kill him.

Because the signal has to go FTL, it has to take on the special reference frame where Alex has already fired the bullet. It therefore cannot be recieved by Stillstorm before Alex fires the bullet, preventing a paradox, preserving Causality, going FTL and making Relativity its bitch.

You can find a much more technical and accurate explanation Here.

In the Outsider Universe, Hyperspace is the special reference frame that allows for FTL, stomps on Relativity, and allows for Causality.

In real life, there is no special reference frame that we are as yet aware of. We have yet to discover any kind of hyperspace. Relativity is ironclad at the moment and becoming more and more ironclad with every experiment that verifies the theory. Causality is too critical to bear letting go of. FTL is the red headed stepchild that has to be left out in the rain. It's harsh and unfair but it's the way our universe works.

As to my personal feelings on there being no FTL in this universe...

[Ktrain]

Gosh that reminds me of my old roommate... Let's just hope that our fundamental understanding of reality is just scratching the surface of knowledge, more space for FTL science (fiction) to hide

I also your empathize with your feelings:

[Trantor]

...
FTL travel and time travel are the same thing.

I agree 100% so far (as usually), at least for our 4-dimensional space at this time.

But maybe - maaayybee(!) - we will see some funny other things in the future.

And if not? Then we still have SF.

[dfacto]

That's a paradox. The universe doesn't like paradoxes. It's allergic to them. Trust me on this, the universe and I are on pretty good terms with each other. Usually.

This is what interests me though. Is there proof? Does it even matter? Would things just get totally off the wall crazy, but not actually impact anything but our perception of reality?

[Cy83r]

Wait wait wait! Okay, so faster-than-light equals negative time, got it. But what does negative time look like? I can't remember where, but I recall reading a book or paper that elucidated on the origin and end of the universe, big bang, big crunch, all of that. The author wrote that, assuming there was a big crunch, the math seems to say that once spatial dimensions hit zero any further compression, which the math IIRC says there is further compression, turned into positive expansion.

So, if space and time are intimately related, then would it not be properly intuitive to guess that things traveling FTL experience time at a speed increasing from a standstill? Imagine from the view of spectators watching the first interstellar jump, the ship compresses and its crew slow to a crawl as they rapidly approach c before, suddenly, the ship jumps away from Sol and the crew begin to speed up and perhaps move at an accelerated pace all while their ship seems to move backwards at faster-than-light speeds. Though I'm pretty sure the actual crew don't notice any of this, or perhaps they see the outside universe the same way they are seen (again, assuming I recall my book-readings correctly).

Would this be a correct layman's interpretation of the data so far?

[Razor One]

The following statement is true.
The previous statement is false.

If the second line is true, the first line is false, meaning the second line cannot be true.

Paradox.

The problem of arriving before you've left means that you've violated causality. You can't arrive before you leave.

In a universe where causality has no place, things do indeed get off the wall crazy.

With causality intact, things proceed from cause to effect.

With causality broken, effects can precede causes and causes can happen without effect.

Pick up a can of coke. It's empty now because you were having been going to drink it. But you haven't yet. Yet it's empty.

Look up in the sky. The sun turned into a red giant. Why? It exhausted its nuclear fuel long before it was supposed to because you threw causality out of the window. The effect of it expanding into a red giant has preceeded the cause of it running low on nuclear fuel.

Rockets suddenly explode on the pad before they've been fueled up. The cemetary where you lay flowers by your dear grandfathers grave suddenly has a headstone with your name on it.

Future alien civilisations invade Earth because humans from the future engaged in a brutal war of genocide against them on the basis that humanity broke free of their tyrannical rule and engaged in a brutal war of genocide to avenge their tyranny.

A world without causality makes no sense, not any kind of sense that we can make head or tail of. Effects can happen without causes. Causes can happen with no effect.

Try and Light a fire. Nothing happens. Your cause has no effect.
A flame spontaneously bursts into life somewhere. Your effect has no cause.

You were born and grew up. But I travelled back in time and killed your mother before you were born. Yet still you live with memories of your mother raising you, because causality is gone. The cause of killing your mother had no effect in removing you from time or changing the universe.

Something closer to home.

Cause: You wrote:

This is what interests me though. Is there proof? Does it even matter? Would things just get totally off the wall crazy, but not actually impact anything but our perception of reality?

Effect: This post.

Now imagine this post popped up before you wrote that, even quoting what you hadn't even written yet.

Now imagine that you didn't even register here in the first place. You never registered here. Let's imagine you never even heard of Outsider or had never logged on to the internet.

Who am I quoting? There is no cause. Just effect.

Cause and effect allow space and time to work in just the way you know and are familiar with. Without it, Science becomes impossible, to say nothing of SCIENCE! You can't make predictions, you can't make observations, you cannot draw conclusions. In a universe with cause and effect, if you mix Hydrogen and Oxygen together, you get a reaction. Without it, you may get no reaction at all, or a reaction before you've mixed them. Just think of all the horrific things that would do to your body chemistry alone.

So yes, causality is extremely important. Things just don't go off the wall crazy, they go completely bonkers, they make Event Horizon look like a pleasant summer trip, you get cats and dogs living together, mass hysteria!

**quick refresh**

Wait wait wait! Okay, so faster-than-light equals negative time, got it. But what does negative time look like? I can't remember where, but I recall reading a book or paper that elucidated on the origin and end of the universe, big bang, big crunch, all of that. The author wrote that, assuming there was a big crunch, the math seems to say that once spatial dimensions hit zero any further compression, which the math IIRC says there is further compression, turned into positive expansion.

So, if space and time are intimately related, then would it not be properly intuitive to guess that things traveling FTL experience time at a speed increasing from a standstill? Imagine from the view of spectators watching the first interstellar jump, the ship compresses and its crew slow to a crawl as they rapidly approach c before, suddenly, the ship jumps away from Sol and the crew begin to speed up and perhaps move at an accelerated pace all while their ship seems to move backwards at faster-than-light speeds. Though I'm pretty sure the actual crew don't notice any of this, or perhaps they see the outside universe the same way they are seen (again, assuming I recall my book-readings correctly).

Would this be a correct layman's interpretation of the data so far?

I'm running on two hours of sleep here and there are spiders are crawling on my hands, but I'll try to answer this as best I can currently.

I'll assume in this scenario you're not throwing out relativity, but causality.

In which case you'll need to repair the scenario somewhat. Relativity absolutely prohibits accelarating up to and beyond C. It is impossible. It requires infinite energy. So long as you maintain relativity in the example, the ship cannot by definition attain or exceed the speed of light.

A ship travelling faster than light would be effectively unobservable except after the fact... before it technically left. You would be seeing ships arriving before they leave and then seeing any incident light they shed arriving long after they arrived themselves and preferably after their earlier selves left to go on the journey they arrived on before they left.

So uh...

We have Starship A.

Starship fA is the ship after it has left and arrived before it leaves.
Starship pA is the ship before it leaves

Starship fA arrives before Starship pA leaves. A light trail from fA is seen arriving going backwards along its journey in FTL tracing back all the way until Starship pA leaves.

From the perspective of a traveller going faster than light...

The only incident light you would be able to see would be directly ahead of you. Anything off to the sides you'd just blow on by. Light trying to catch up to you never would. This would create a tunnel like effect. Darkness all around you, light ahead of you.

However, since you're travelling FTL, the compression of light would probably roast you. Actually, I have no idea what it would do to you. Asking what happens when you strike an STL object at FTL has no sane answer. If you must have one, your starship turns into pumpkins. Or a flower pot and a sperm whale. Whichever works.

The one key thing I will advise when it comes to physics is to throw intuition out the window. Relativity, quantum mechanics and a whole slew of cutting edge physics is very much counter-intuitive in all their forms. Entanglement scares the bejeesus out of some physicists while what exactly lies in the center of a black hole others.

As good start to the headscratching on counter-intuitivity, ask yourself a question.

What is mass?

No, not weight. Weight is the result of gravity acting on mass. What exactly is mass?

I recently learned a few head explodingly counter-intuitive things about mass recently.

An object with potential or kinetic energy has more mass than object without potential or kinentic energy.

If mass is a property of matter, how is it possible for kinetic and potential energies to increase the mass of an object relative to objects without that extra property?

In laymans terms, I have a coke can on the ground. I have an identical coke can on my desk. The coke can on my desk is a meter higher than the coke can on the ground. Physics tells us that the coke can on the desk has more mass than the coke can on the ground because of the extra potential energy it has.

Likewise, if I were to throw yet another coke can, it would have more mass than the coke can at rest on the ground because it has extra kinetic energy.

I've changed nothing with respect to the physical makeup of all three cans. The only property that has changed is that energy has been added, kinetic or potential.



And that's one of the least mind blowing things about physics lately. With any luck they'll nail Higgs arse to the wall.

And now I'm off to catch one hour of sleep before I must arise and head out to Uni. Ugh.

[Arioch]

Okay, so faster-than-light equals negative time, got it. But what does negative time look like?

It doesn't look like anything, because it doesn't (and can't) exist.

[Cy83r]

No, my point is that you're assuming: a) there is not a way around the lightspeed barrier by ignoring mass... somehow (tachyons with their imaginary mass, maybe, if they exist and if they can be caught without negating their needed properties); and, more importantly, b) that negative time implies time travel.

Also, I think I may have figured a way around an FTL object meeting and STL object. Since the traveler's energy is so high there might be a very good chance that the FTL object proceeds to quantum tunnel through whatever it hits. The only problem is that this implies that tachyons and similar particles won't be very easy to catch, if at all; let alone detect.

Edit: an object higher up a gravity well has more mass than one lower down? That makes some sense, though that makes it seem like weight and mass are tied together in some... perhaps geometric function? Objects in motion having more energy and thus mass has been something of a modern-day no-brainer for a while though.

Lastly, we always have spacetime shortcuts like wormholes to investigate, which, as far as I'm still aware, don't violate relativity (which is still incomplete, by the way) or causality (which still makes sense from a fourth or fifth dimensional perspective even when broken, or perhaps causality looks insane from those higher viewpoints). Hell, broken causality made an excellent game about time travel warfare called Achron. Not to mention that I have a couple RPG plots that abuse causality. So, perhaps the ideas of relativity and causality are what's broken, they don't [completely] accurately portray the truth of how the universe works in its entirety, it just explains things on our mundane level.

P.S. And another thing, and this is far out so not very important to answer, don't we sort of violate causality just by trying to predict others' actions and respond accordingly? The cause of a preemptive action is technically the probability of a future event occurring, even if based on current observations, you are still making a hypothetical leap into a future where this possibility exists and then acting on it.

[dfacto]

With causality broken, effects can precede causes and causes can happen without effect.

Pick up a can of coke. It's empty now because you were having been going to drink it. But you haven't yet. Yet it's empty.

Look up in the sky. The sun turned into a red giant. Why? It exhausted its nuclear fuel long before it was supposed to because you threw causality out of the window. The effect of it expanding into a red giant has preceeded the cause of it running low on nuclear fuel.

Rockets suddenly explode on the pad before they've been fueled up. The cemetary where you lay flowers by your dear grandfathers grave suddenly has a headstone with your name on it.

Future alien civilisations invade Earth because humans from the future engaged in a brutal war of genocide against them on the basis that humanity broke free of their tyrannical rule and engaged in a brutal war of genocide to avenge their tyranny.

A world without causality makes no sense, not any kind of sense that we can make head or tail of. Effects can happen without causes. Causes can happen with no effect.

And my question is, "so what?"

Just because it makes no sense doesn't necessarily mean anything at all (Hi quantum mechanics, you sick twisted hellscape you), other than that we're in for some seriously bonkers stuff. Is there some physical roadblock to causality violations (other than FTL seeming to be impossible)? Maybe we haven't observed paradoxes simply due to lack of contact with FTL capable civilizations? Maybe one day we'll colonize other solar systems before constructing the colony ships, but will that just be us scratching our heads or will the universe bear any effect from the paradox?

If I had to guess though it's a moot point and FTL is just not going to happen.

Okay, so faster-than-light equals negative time, got it. But what does negative time look like?

I doubt you could perceive anything beyond the scope of our 3d space-time. An FTL ship would probably just disappear.

But... if it had to look like something, then for sure like this

[Karst45]

hehe, I really hope Dec 21, 2012 doesn't happen. Looking forward to seeing what is coming next.

If you base your assumption (like most media did) that because the Mayan Calender end that it also mean the end of the world, rest assured, it wont happen because Mayan calendar, like all their believe, is based on the circle. On other word, there is no end to the Mayan calender.

All that is know is that the Mayan did observe something important in the past, important enough for them to Mark it on the stone. They did that because, in their believe that everything is cycling, they tough that this particular even would come again.

So something important will happen, the end of the world? probably not, though lots of people will panic because of the misinformation that most media are using to instigate fear (you fight the terrorist but your actually Terrorizing your own population. can you feel the irony?)

So that mostly it, dont fear the end of the world, but you still can sell those survival kit / bunker some sucker will buy them anyway

So, in conclusion: dammit, let me think we at least have a chance at it until the hard numbers get back in the next several decades! Psychic powers have been dead and buried for almost the last two decades, don't take away my FTL drives just yet, we aren't even on Mars.

Well i wouldn't worry about that. it been show (maybe as a joke but still) that it would be mathematically impossible for ANYTHING heavier than air, to fly and also that anything going faster than 55 mph would be vaporized. So if i know something is that science is good at convincing people of what they cannot do. It like the Politician, It (the science) say convincing lies, until proven otherwise, afterward they just apologizes for their error but everyone already forgot what it was all about and keep voting for them.

[discord]

razor: E=mc2(yeah i know, can't be arsed figuring out how to do a squared 2) tells us that objects in motion have more energy, therefor a increase in energy without a increase in speed should be a increase in mass...these are still pretty small value changes though.

and something that always bothered me with the 'no rest frame' is the speed of light....what exactly is it relative to? and that always makes me think of the speed of sound, there seems to be several similarities here, as you approach the 'barrier' you need more and more energy to overcome.....something in the way...the faster you go, the more wave front you are building up in front of you, creating drag hindering further acceleration...

so, my theory here is that the speed of light is merely the speed of sound in a near vacuum. now chew on that you damn physicists.

[Cy83r]

razor: E=mc2(yeah i know, can't be arsed figuring out how to do a squared 2) tells us that objects in motion have more energy, therefor a increase in energy without a increase in speed should be a increase in mass...these are still pretty small value changes though.

and something that always bothered me with the 'no rest frame' is the speed of light....what exactly is it relative to? and that always makes me think of the speed of sound, there seems to be several similarities here, as you approach the 'barrier' you need more and more energy to overcome.....something in the way...the faster you go, the more wave front you are building up in front of you, creating drag hindering further acceleration...

so, my theory here is that the speed of light is merely the speed of sound in a near vacuum. now chew on that you damn physicists.

Sound is a wave function of a vibrating cloud of particles, vacuum doesn't transmit sound because there's not enough stuff to bump the energy through. The something to push past in regards to the light-speed barrier is your increasing mass, rather than the stacking air pressure in front of a hypersonic aircraft, it takes mass to move mass; though, interesting thought, the mass of your unused propellant increases with the ship, should a mass-holding object reach lightspeed and thus become infinitely massive, the propellant also becomes... infinite? I got something wrong there. The idea behind FTL drives harnessing tachyons is that the particle holds negative/imaginary mass, potentially negating the mass of the ship or inverting it entirely, allowing the vessel to quaintly ignore the light barrier, but catching them, assuming they exist at all, is the problem; wormholes ignore the entire problem all together by ripping spacetime apart and creating a new shorter path to the destination, but the logistics of exploiting existing wormholes, creating new ones, and aiming them are about as feasible as creating an interstellar empire using slowboats, again, this assumes wormholes exist in the first place.

Oh, the speed of light also changes depending on the medium it moves through, so c is considered the speed of light in a perfect vacuum.

[junk]

Causality wall of text

Alright I believe I understand the premise. But keep in mind that this effects conventional space FTL. If you have nonconventional space FTL you shouldn't have any causality issues either.

Either by using the different reference frame as you mention or alternatively using the various technobabble space folding techniques. Admittedly technobabble.

On another note - was quatun tunneling disproven or not? I remember it coming up a few years ago.

[NOMAD]

hehe, I really hope Dec 21, 2012 doesn't happen. Looking forward to seeing what is coming next.

If you base your assumption (like most media did) that because the Mayan Calender end that it also mean the end of the world, rest assured, it wont happen because Mayan calendar, like all their believe, is based on the circle. On other word, there is no end to the Mayan calender.

All that is know is that the Mayan did observe something important in the past, important enough for them to Mark it on the stone. They did that because, in their believe that everything is cycling, they tough that this particular even would come again.

So something important will happen, the end of the world? probably not, though lots of people will panic because of the misinformation that most media are using to instigate fear (you fight the terrorist but your actually Terrorizing your own population. can you feel the irony?)

So that mostly it, dont fear the end of the world, but you still can sell those survival kit / bunker some sucker will buy them anyway

Well I don't have any survival kits for sale but I might get one, just in case: since you never know what will happen in life).

you make a valid point, its impossible to know what they saw, bad or good. yet, I'll be spending time with my family either way, what ever comes on that date

[Razor One]

No, my point is that you're assuming: a) there is not a way around the lightspeed barrier by ignoring mass... somehow (tachyons with their imaginary mass, maybe, if they exist and if they can be caught without negating their needed properties);

Define Mass.

Given that all matter has mass, the only way to get to lightspeed is to shed mass entirely, or in simpler terms, cease to be matter. Photons do this through wave particle duality and quantum mechanics. The only way that wave particle duality can happen is on the quantum scale, photons, electrons and such. Atoms generally cannot behave in this manner. Classical objects, such as yourself or my favored can of coke, cannot and never will have any kind of wave particle duality to conveniently ignore their mass because they are not on the quantum scale at which these effects could occur.

and, more importantly, b) that negative time implies time travel.

Time is another dimension in our generally four dimensional and arbritrarily 11 dimensional universe. You can't have negative length. You can only have length that increases in a different direction.

Likewise, you can't have negative time, it's a misnomer You can only have time that flows in a different direction. 'Negative' time can only be time that flows in a manner opposite to regular time. Regular time flows forwards. 'Negative' time would have to flow backwards. Relativity has no preference for the directionality of time.

Also, I think I may have figured a way around an FTL object meeting and STL object. Since the traveler's energy is so high there might be a very good chance that the FTL object proceeds to quantum tunnel through whatever it hits. The only problem is that this implies that tachyons and similar particles won't be very easy to catch, if at all; let alone detect.

Quantum tunnelling only occurs on the quantum scale. Macroscale classical objects cannot be quantum.

Edit: an object higher up a gravity well has more mass than one lower down? That makes some sense, though that makes it seem like weight and mass are tied together in some... perhaps geometric function? Objects in motion having more energy and thus mass has been something of a modern-day no-brainer for a while though.

I think you've misunderstood.

Weight and mass are tied together. Weight is the phenomenon of gravity acting on mass.

Mass is generally described as a property of matter. I suppose it is a bit obvious in hindsight that since E=MC^2 the addition of any kind of energy to an object would increase its mass by a corresponding amount... I just don't recall that connection ever being made during ye olde Highschool Physics. Then again my teacher for that was a bit pathetic...

Lastly, we always have spacetime shortcuts like wormholes to investigate, which, as far as I'm still aware, don't violate relativity (which is still incomplete, by the way) or causality (which still makes sense from a fourth or fifth dimensional perspective even when broken, or perhaps causality looks insane from those higher viewpoints). Hell, broken causality made an excellent game about time travel warfare called Achron. Not to mention that I have a couple RPG plots that abuse causality. So, perhaps the ideas of relativity and causality are what's broken, they don't [completely] accurately portray the truth of how the universe works in its entirety, it just explains things on our mundane level.

Source on broken causality still making sense from a fourth and fifth dimensional perspective? I'd like to read that.

Broken causality can make for some excellent fiction. As it stands though, it appears to be a very solid and non-negotiable part of reality.

P.S. And another thing, and this is far out so not very important to answer, don't we sort of violate causality just by trying to predict others' actions and respond accordingly? The cause of a preemptive action is technically the probability of a future event occurring, even if based on current observations, you are still making a hypothetical leap into a future where this possibility exists and then acting on it.

That doesn't break causality.

Cause: We see a boulder hurtling towards us.
Effect: We react to the boulder.

We don't violate causality by being able to predict that if we do nothing the boulder will crush us into paste and move out of the way accordingly. Cause and effect are maintained. The reaction itself is an effect of the cause. Likewise, if we did nothing and didn't react to the boulder, subsequently getting crushed by it, that too would be an effect of the cause.

Asimov wrote a good story once dealing with cause and effect. I can't recall the name of the story but it relied on a chemical reaction. It was argued that if timed just right, a certain substance would dissolve in water before it actually touched it. When they tried to break causality by preventing the substance from actually dissolving in water, they faced all kinds of natural disasters and deleterious effects until they finally dunked the substance in water.

What resulted of course was an ability to predict the future. If a certain disaster were to occur, the substance would dissolve and you'd know something was up. The applications were intimated that the Russians had already cracked the phenomenon and were using it to brutal effect to bring accident rates down and have a practically flawless space program.

'Fraid that's all the time I have before work. I'll try to get around to answering more questions as best I can after I get back.