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

[Teleros]

I don't know whether I've been doing too much thinking or something (or more likely, too little), but I've been having trouble getting my head around why the speed of light is so important when it comes to high velocities and the like. As I'm trying to create a universe that's at least fairly consistent with what we know about physics, and have a tendency to try and think about these things anyway, I thought I'd see if anyone here could help a little. Apologies in advance for any muddy thinking: it's late, I'm tired, and it's a first draft. And written by someone whose science qualifications consist of a mere GCSE A-grade in physics and a love of sci-fi (ie practically nothing) ...


Anyway, let's say you have a low-tech species that relies on sound and has nothing that travels faster than sound. One day, they develop a supersonic jet, or weapon, or whatever. To them, it appears that it just broke all the rules on causality - it arrived before the sound of its passing did. Yet to our eyes it didn't.
Now put humans in the place of the above species: they somehow develop an FTL starship (no fancy hyperspace or anything, just normal space), and launch it from Mars to the Earth. The ship, very obviously, travels between the two points, and takes time to do so (it's not that fast ). However, we don't see it arrive because it literally outpaced its own image. So where does that mean time travel? As I see it, the best you can say is that it appeared to be time travel, because you couldn't see it until after it had arrived. However, that doesn't change the fact that it obviously had arrived, and took time to do so. If we had FTL sensors, we'd've been able to see it travel too.

Also, consider the point of view of 3 observers, one at the start, finish and middle of the route:
-The first sees the ship at Mars. A moment later, and it disappears. A short while later (depending on how much faster than light it travels), the light from the ship above Earth reaches him. Because the light from the ship takes time to go from Earth to Mars, he will always see it in this order. No problem here.
-The second sees the ship at Mars preparing to leave. A moment later, before it has appeared to leave Mars, it is visible in orbit over Earth. Rather than time travelling however, the ship simply outran the last image of itself from Mars, and arrived first - even though nobody saw it do so. Here apparently is the problem, at least as I understand it.
-The third observer, being equidistant from Mars & Earth, and because the trip from one to another takes time even for the FTL ship, observes the ship departing Mars orbit before arriving in Earth orbit. No problem here.

My point is why it's not possible to say that "ok, the thing travelled faster than light, therefore it appeared to travel through time". Granted you might not be able to tell a time traveller from an FTL traveller but that wouldn't matter because the traveller would know:
-Assume that I can travel at 100c between star systems, and want to arrive at Tau Ceti in time for lunch in a particular city. I check the distance from Tau Ceti to Earth, work out how long light takes to travel from one to the other, and look through a telescope to see where the inhabited planet is. Factor in time to travel there at 100c, the length of the orbit etc, and off I go.
-Once I arrive on Tau Ceti III or whatever we call it, I go about my business. A few years later, my ship can be observed leaving Earth. Have I time travelled? Of course not - if you could magically teleport from Tau Ceti to Earth instantaneously, my ship would not be in orbit there, and I would have left in time to have arrived at Tau Ceti when I did.

As I see it, the only problem is that it probably requires some sort of universal frame of reference. I suppose for me this is the actual position of the matter at any one time - those last 3 words being the problem. However, because observers can interact and exchange information, is this really a problem? When I see you walking, I can watch your position move from A to B to C - or to be more precise, your position a minute fraction of a second ago. However, because we can communicate - even touch - we can figure out where we are (or were, perhaps) in relation to one another. So why can't we scale this up to encompass say, interstellar distances? Can you not maintain causality yet appear to break it from one point of view*?

* Perhaps an "apparent" and "actual" causality - the former would be the point of view of any one observer, the latter should they get together and work out what happened (or had a universal frame of reference, FTL sensors or somesuch). Would this work, and if not how badly?



Finally, on a (mostly) unrelated note, what happens when you introduce to a universe:
-A speed limit above that of light for information (eg your good old telepathy)?
---Obviously picking up signals might be a problem given how fast they'd go through something as small as a human head or satellite dish, but what else?

-A scanner that can observe without in any way interfering with the observed?
---What effect would it have if I could, say, determine precisely the position and momentum of a particle? How would quantum physics work (or not) with such tools?

[Apollonius]

I believe you overlooked one detail. The Speed of Light, c, is not actually defined by the speed of light, i.e. by the distance a photon can travel within a given time. "Speed of Light" is a misnomer. I know nothing about the underlying math, but I think that light simply travels at the highest possible speed and is limited by c. But c is independent of the actual speed of light; in fact, c would still be there and be still the same value, if light never existed in our universe. Furthermore, it is possible to slow down light, but that doesn't concern c. c is only called the "Speed of Light" because we used light to detect it. We could just as well call it the Speed of Information.
Maybe you should decouple your line of thoughts from optic phenomena.
For reasons I couldn't claim to understand, a ship travelling at superluminal speed would not merely appear to travel back in time (provided it would survive this trip), but really mess up causality and maybe some other related stuff, like spacetime or the universe itself, who knows.
The reason is that c does not only govern photons, but a whole host of fundamental processes. I'm sure there will be 20 replies by people who understand this stuff better than me. But I'm sure they will all say that a superluminal ship does more than merely outrun its own image. For one, the closer you get to c, the more your mass increases. At c your mass is infinite. I bet such a concentration of mass can have some nasty effects on the dimension of time (we already know - and have even empirically verified - that mass does affect space itself, so why stop at 3 dimensions?).
True-space faster-than-light travel seems way too improbable (sadly), that's why hyperspace, wormholes and jumpgates were invented in science fiction, because their unlikeliness is less apparent.

[Braedley]

You're thinking in purely Newtonian physics. This is fine if all you ever do is talk about velocities less than about 0.1c, and gravity wells no deeper than a few thousand solar masses. However, after this, things start to break down. The reason for this is that the speed of light is constant in any inertial frame. I'll give you a second for how profound this is to sink in.


Consider you're on the edge of the Milky Way, looking at, oh say the Andromeda Galaxy. Let's set our first inertial frame to be the centre of the Milky Way. Also, let's shoot a laser towards Andromeda. Now let's consider that a ship is leaving the Milky Way and headed towards Andromeda at a very high velocity, say on the order of 10^8m/s (or greater than 0.33c). Let's set our second inertial frame to be that of the ship, since it's not going to be accelerating compared to our first inertial frame. Time to bend your mind. Both observers that are stationary in the first frame (ie you) and the second frame (ie the people on the ship) calculate that the light from the laser travels past them at ~3.0*10^8m/s. Newtonian physics says that the passengers on the ship should calculate the light to be traveling less than 2.0*10^8m/s (depending on their exact velocity), so to compensate, the math says that time must be passing slower for people that are stationary in the second frame than those stationary in the first frame. To extend this, if the ship is traveling faster than 3.0*10^8m/s, then Newtonian physics would say that the light was traveling towards the Milky Way, according to observers on the ship. Therefore, to keep the light traveling at c in the second frame of reference, time has to reverse for those in the second frame.

Try to wrap your head around it, even though it can be a little difficult when considering velocities near or above c. I don't have a full grasp of the math, but I understand the concept as well as any one possibly could without taking at least high bachelors degree courses on the material.

[Kuroneko]

Anyway, let's say you have a low-tech species that relies on sound and has nothing that travels faster than sound. One day, they develop a supersonic jet, or weapon, or whatever. To them, it appears that it just broke all the rules on causality - it arrived before the sound of its passing did. Yet to our eyes it didn't.

I'm not sure how to interpret this. Why would the speed of sound be connected to their conceptualization of causality? For that to be the case, they would have to have a spacetime with a fundamental speed v_s instead of c, but that's extremely easy to falsify. But since this is apparently tangential to you main point, let's move on...

Now put humans in the place of the above species: they somehow develop an FTL starship (no fancy hyperspace or anything, just normal space), and launch it from Mars to the Earth. The ship, very obviously, travels between the two points, and takes time to do so...

The conclusion that the ship "really" broke causality follows under the assumption of a flat background spacetime. So, if the ship actually did travel some distance in this manner, rather than just fooling us into believing so, then there are some possibilities to explain this:
(1) The ship did not distort spacetime, meaning the special theory of relativity is fatally flawed. This is virtually impossible, given that STR is the most well-tested and successful theory we have (something usually said of QED, but every test of QED is also a test of STR), so hard sci-fi doesn't take this possibility seriously.
(2) The ship did distort spacetime, and GTR is at least roughly correct, meaning the ship's crew is at least a Type III or greater civilization all by itself, able to summon galaxy-sized power outputs just on that ship alone. In fiction, not even Culture-level tech is this absurd.
(3) Magic (with Clarke's law as the criterion), the approach used in most sci-fi with FTL, only they tend to either disguise it in meaningless babble or not explain it at all. This includes warping spacetime while ignoring GTR's limits on such things (Star Trek).

[Apollonius]

---What effect would it have if I could, say, determine precisely the position and momentum of a particle? How would quantum physics work (or not) with such tools?

There may be a definite answer to that question, but I don't think that it is known to anyone at this time.
I suspect however that it would remove the concept of uncertainty from the whole theory. In such a universe, everything, both the macrocosm and microcosm, would be governed by deterministic causality. The question "what caused it?" would be meaningful for every single event in the universe, probably necessitating either that the age of the universe is infinite, or that it was created by a transcendent entity (a god), or that it was "born" from a universe that does know the concept of quantum uncertainty. Spontaneous creation of particles (quantum foam) probably wouldn't exist either, which would mean that black holes never evaporate (if I understand Hawking Radiation correctly).
Chemistry and everyday physics would likely be the same, unless the fact that electrons would be confined to existing at definite locations at defined points of time (as opposed to the way they behave right now) would make them somehow less able to hold molecules together.

I won't be too surprised if someone came along and informed me that everything I said is wrong. But in my experience, questions like yours, as interesting as they are, usually get answers like "that question is meaningless" or "there is no such thing" from most experts. It's like when someone asks what was before the Big Bang. Experts apparently don't like to speculate as much as we laymen do, so we need to provoke them a little to get them going.

[Teleros]

But I'm sure they will all say that a superluminal ship does more than merely outrun its own image. For one, the closer you get to c, the more your mass increases. At c your mass is infinite. I bet such a concentration of mass can have some nasty effects on the dimension of time (we already know - and have even empirically verified - that mass does affect space itself, so why stop at 3 dimensions?).

I know about that and don't have a problem with needing impossibly high energies to travel at FTL speeds (or the increase in mass). Maybe it's a silly question, but I'm trying to understand why else it's impossible (not that you really need any more reasons ).

I suspect however that it would remove the concept of uncertainty from the whole theory.

So perhaps a deterministic universe from the get go, made uncertain to the observer through the act of observation (prior to the magic scanner)?


Braedley & Kuroneko, I'll have a proper look at your replies when I've had a few hours of sleep.

[Apollonius]

Have you considered what the effects of infinite mass would be on the internal structure of the ship? How would the crew survive under such conditions? The whole inertial system would instantly become a black hole, or worse (I'm sure there is even worse than a black hole, heh).
I recently read a SF story that involved ships not travelling through space, but moving a bubble of space that contained them through the rest of space. That way they avoided the nasty effects of acceleration and relativity. I don't know if moving a portion of space itself is actually thinkable, but it would be a neat solution to many problems.

[starslayer]

Apollonius, nothing with mass can travel at c because it takes an infinite amount of energy to get there; the infinite amount of relativistic mass the thing would have is irrelevant. To a photon, the universe has no length in its direction of motion, and it feels no time pass. Once something hits c, it can never change its speed; it literally doesn't have time to. Quantum mechanically, I'm not sure where c comes from, but classically (and relatively), it comes from deriving a solution of the wave equation from Maxwell's equations. This yields a speed of 1/sqrt(ε_0*μ_0), or about 3E8 m/s, the speed of light, c. No one is sure just why c is the universal speed limit, but it is, as it is the speed of a massless particle.

[Darth Raptor]

It sounds perverse, but the actual mechanics of the the transition are the "easy" part (or at least, thinking up plausible-sounding ways to cheat around the light barrier is relatively easy). A two-way jump, i.e., jumping, flying or transitioning between two points faster-than-light with the ability to return home is far more tricky, because FTL travel is, by definition, time travel. So while you might have made it across the known universe, it ain't your universe anymore, because your accidental time machine just dropped its trousers and took a huge dump all over causality (you know, the principle of causes preceding effects? Not with FTL). So either, your wars are fought and your people live in a tangled mess of polluted timelines and interconnected futures (interesting, but chaotic as all hell), the Time Cops prevent you from making paradoxes or all FTL travel and communication uses the same inertial frame of reference. The last one is preferable, for obvious reasons. Pity it's almost certainly not true.

[Apollonius]

Apollonius, nothing with mass can travel at c because it takes an infinite amount of energy to get there;

I'm aware of that, but Teleros already said he's not concerned with how much energy it would take. Maybe he uses alternate universes as fuel, or something.

I find it hard to understand how it must be like to be a photon. If it doesn't experience time, then its birth and its death must occur at the same time. If photons were sentient, would they perceive their existence as eternal or wouldn't they even have time to think "holy crap, I ex..."?

[Teleros]

Therefore, to keep the light traveling at c in the second frame of reference, time has to reverse for those in the second frame.

Think I've got you: to do what I'm talking about would mean checking with some universal frame of reference, which as Darth Raptor pointed out is... unlikely.

The conclusion that the ship "really" broke causality follows under the assumption of a flat background spacetime. So, if the ship actually did travel some distance in this manner, rather than just fooling us into believing so, then there are some possibilities to explain this

If I'm reading this right then, (1) would probably allow Lensman-esque inertialess travel (if a ship travels for 2hrs at 100c, 2hrs have also passed on Earth, Klovia, and any other planet you care to name). That series also appears to have something akin to the luminiferous aether though, so we can probably stop there.

Have you considered what the effects of infinite mass would be on the internal structure of the ship? How would the crew survive under such conditions? The whole inertial system would instantly become a black hole, or worse (I'm sure there is even worse than a black hole, heh).

Children of the Lens: two planets are fired from another universe into our own at 15c, whilst inert and all that. It takes Arisian magitech to ensure that the universe doesn't accidentally collapse around them both in zero time. Incidentally, the target planet was merely blown to smithereens, the target star became a 500-million-Sol supernova, and the universe was fine.
No idea if that's what would happen (as gravity propagates at c, would that limit the speed of the collapse?), but there we go.

I recently read a SF story that involved ships not travelling through space, but moving a bubble of space that contained them through the rest of space. That way they avoided the nasty effects of acceleration and relativity. I don't know if moving a portion of space itself is actually thinkable, but it would be a neat solution to many problems.

Isn't that the basis for the Alcubierre drive?

I'm aware of that, but Teleros already said he's not concerned with how much energy it would take. Maybe he uses alternate universes as fuel, or something.

For the record, my little universe uses good old hyperspace to cheat, wormholes and things like "infinite energy" being too, well, energy intensive to achieve.

If photons were sentient, would they perceive their existence as eternal or wouldn't they even have time to think "holy crap, I ex..."?

I'd assume that if no time passed, they'd never be able to think. About the only way I can imagine them being able to would be through slowing them down...


Any other thoughts on the FTL comms & the magic scanner? Apart from the former also playing merry hell with Einstein I mean .

[Ariphaos]

Think I've got you: to do what I'm talking about would mean checking with some universal frame of reference, which as Darth Raptor pointed out is... unlikely.

However unlikely, it's the only feasible answer that can be contorted to both fit with relativity as we can currently observe it and maintain causality without doing some rather absurd gymnastics (like the Universe magically preventing violations). At least that I'm aware of - every other solution I've seen runs into serious problems.

A fixed frame must handle the expansion of spacetime (via being a hypersphere or whatever), so it's useful to ponder whatever form that takes.

If I'm reading this right then, (1) would probably allow Lensman-esque inertialess travel (if a ship travels for 2hrs at 100c, 2hrs have also passed on Earth, Klovia, and any other planet you care to name). That series also appears to have something akin to the luminiferous aether though, so we can probably stop there.

One of your problems is that (some number greater than 1) times c has little sensible meaning without a distinct mention of the frame of reference it is being measured in. Otherwise, there is a frame of reference in which your 100c is actually slower than c, accelerating to .86 c first lets you 'double' your speed, etc. These contortions are the sort of holes causality violations creep in, and unless you want them you need to dodge that entirely.

Think of c as a sort of infinity. You are saying "100 times infinity" well...

Children of the Lens: two planets are fired from another universe into our own at 15c, whilst inert and all that. It takes Arisian magitech to ensure that the universe doesn't accidentally collapse around them both in zero time. Incidentally, the target planet was merely blown to smithereens, the target star became a 500-million-Sol supernova, and the universe was fine.
No idea if that's what would happen (as gravity propagates at c, would that limit the speed of the collapse?), but there we go.

Distance is relative, and so is time - relativity does not exist as we know it in the Lensman Universe. Just as your current measured distance to something depends on your velocity, so does your 'now'.

Isn't that the basis for the Alcubierre drive?

And refinements of it, see Kuroneko's #2 point. Alcubierre's method required something like ten times the mass of the Universe in negative energy and more than a dozen times that in positive energy, to establish the bubble. Refinements have gotten it down to units measured in solar masses through various contortions. I can't claim to understand it, however.

* Perhaps an "apparent" and "actual" causality - the former would be the point of view of any one observer, the latter should they get together and work out what happened (or had a universal frame of reference, FTL sensors or somesuch). Would this work, and if not how badly?

Almost.

When events a and b occur outside of each others' light cones, it's possible for any external observer to either assume a or b occurred first, depending on their frame of reference. If there is a fixed frame (see caveat above), then those who are aware of such a frame might be able to work out the true ordering.

Finally, on a (mostly) unrelated note, what happens when you introduce to a universe:
-A speed limit above that of light for information (eg your good old telepathy)?
---Obviously picking up signals might be a problem given how fast they'd go through something as small as a human head or satellite dish, but what else?

You need to consider the mechanism of the signal. See above about 'x times c'.

-A scanner that can observe without in any way interfering with the observed?
---What effect would it have if I could, say, determine precisely the position and momentum of a particle? How would quantum physics work (or not) with such tools?

These two issues are separate - the latter is a fundamental property of the nature of particles on a quantum mechanical scale. The former would not give you the latter.

[Teleros]

However unlikely, it's the only feasible answer that can be contorted to both fit with relativity as we can currently observe it and maintain causality without doing some rather absurd gymnastics (like the Universe magically preventing violations). At least that I'm aware of - every other solution I've seen runs into serious problems.

I'm assuming the same thing. Aside from allowing FTL travel that doesn't screw up causality (in principle at least), what would be the other effects of a universal frame of reference?

These two issues are separate - the latter is a fundamental property of the nature of particles on a quantum mechanical scale. The former would not give you the latter.

Perhaps if I rephrase it then: what would be the effects of being able to ignore the observer effect?

[Singular Intellect]

The question "what caused it?" would be meaningful for every single event in the universe, probably necessitating either that the age of the universe is infinite, or that it was created by a transcendent entity (a god), or that it was "born" from a universe that does know the concept of quantum uncertainty.

Your 'god did it' idea is utterly fucking stupid, as it always is and will be. You may as well have said "created by a giant magic fairy", as if that has any substance or credibility to explain fuck all about anything.

I won't be too surprised if someone came along and informed me that everything I said is wrong. But in my experience, questions like yours, as interesting as they are, usually get answers like "that question is meaningless" or "there is no such thing" from most experts. It's like when someone asks what was before the Big Bang. Experts apparently don't like to speculate as much as we laymen do, so we need to provoke them a little to get them going.

No, experts are simply smart enough to understand the question has no meaning. It's like asking "What does hope smell like?", or "What is the colour of abstraction?", or "Why are Unicorns hollow?".

You may as well be taking all the alphabet letters and shaking them up into random combinations and demanding someone explain the meaning of those 'words'. It's an exercise in gross futility and stupidity.

[Strider]

I don't know whether I've been doing too much thinking or something (or more likely, too little), but I've been having trouble getting my head around why the speed of light is so important when it comes to high velocities and the like. As I'm trying to create a universe that's at least fairly consistent with what we know about physics, and have a tendency to try and think about these things anyway, I thought I'd see if anyone here could help a little. Apologies in advance for any muddy thinking: it's late, I'm tired, and it's a first draft. And written by someone whose science qualifications consist of a mere GCSE A-grade in physics and a love of sci-fi (ie practically nothing) ...


Anyway, let's say you have a low-tech species that relies on sound and has nothing that travels faster than sound. One day, they develop a supersonic jet, or weapon, or whatever. To them, it appears that it just broke all the rules on causality - it arrived before the sound of its passing did. Yet to our eyes it didn't.
Now put humans in the place of the above species: they somehow develop an FTL starship (no fancy hyperspace or anything, just normal space), and launch it from Mars to the Earth. The ship, very obviously, travels between the two points, and takes time to do so (it's not that fast ). However, we don't see it arrive because it literally outpaced its own image. So where does that mean time travel? As I see it, the best you can say is that it appeared to be time travel, because you couldn't see it until after it had arrived. However, that doesn't change the fact that it obviously had arrived, and took time to do so. If we had FTL sensors, we'd've been able to see it travel too.

Also, consider the point of view of 3 observers, one at the start, finish and middle of the route:
-The first sees the ship at Mars. A moment later, and it disappears. A short while later (depending on how much faster than light it travels), the light from the ship above Earth reaches him. Because the light from the ship takes time to go from Earth to Mars, he will always see it in this order. No problem here.
-The second sees the ship at Mars preparing to leave. A moment later, before it has appeared to leave Mars, it is visible in orbit over Earth. Rather than time travelling however, the ship simply outran the last image of itself from Mars, and arrived first - even though nobody saw it do so. Here apparently is the problem, at least as I understand it.
-The third observer, being equidistant from Mars & Earth, and because the trip from one to another takes time even for the FTL ship, observes the ship departing Mars orbit before arriving in Earth orbit. No problem here.

My point is why it's not possible to say that "ok, the thing travelled faster than light, therefore it appeared to travel through time". Granted you might not be able to tell a time traveller from an FTL traveller but that wouldn't matter because the traveller would know:
-Assume that I can travel at 100c between star systems, and want to arrive at Tau Ceti in time for lunch in a particular city. I check the distance from Tau Ceti to Earth, work out how long light takes to travel from one to the other, and look through a telescope to see where the inhabited planet is. Factor in time to travel there at 100c, the length of the orbit etc, and off I go.
-Once I arrive on Tau Ceti III or whatever we call it, I go about my business. A few years later, my ship can be observed leaving Earth. Have I time travelled? Of course not - if you could magically teleport from Tau Ceti to Earth instantaneously, my ship would not be in orbit there, and I would have left in time to have arrived at Tau Ceti when I did.

As I see it, the only problem is that it probably requires some sort of universal frame of reference. I suppose for me this is the actual position of the matter at any one time - those last 3 words being the problem. However, because observers can interact and exchange information, is this really a problem? When I see you walking, I can watch your position move from A to B to C - or to be more precise, your position a minute fraction of a second ago. However, because we can communicate - even touch - we can figure out where we are (or were, perhaps) in relation to one another. So why can't we scale this up to encompass say, interstellar distances? Can you not maintain causality yet appear to break it from one point of view*?

* Perhaps an "apparent" and "actual" causality - the former would be the point of view of any one observer, the latter should they get together and work out what happened (or had a universal frame of reference, FTL sensors or somesuch). Would this work, and if not how badly?



Finally, on a (mostly) unrelated note, what happens when you introduce to a universe:
-A speed limit above that of light for information (eg your good old telepathy)?
---Obviously picking up signals might be a problem given how fast they'd go through something as small as a human head or satellite dish, but what else?

-A scanner that can observe without in any way interfering with the observed?
---What effect would it have if I could, say, determine precisely the position and momentum of a particle? How would quantum physics work (or not) with such tools?

[Strider]

Note: I accidentally lost my post and posted a big quote just above, could a mod delete it?

Finally, on a (mostly) unrelated note, what happens when you introduce to a universe:
-A speed limit above that of light for information (eg your good old telepathy)?
---Obviously picking up signals might be a problem given how fast they'd go through something as small as a human head or satellite dish, but what else?

If such a method existed, one could construct two highly powerful super-devices

1) Using FTL transmission of information back and forth between two "spaceships" accelerating back and forth at realspace velocities near c (with sufficiently awesome technology, this could be miniaturized), you could send the results of any calculation back in time and eventually in a circle between the two ships. This allows you to perform an infinite number of flops in no time at all, and with no expenditure of resources, since the moment you ask your "computer" the question it transmits the answer to you. An advantage of this device is that it does not violate causality if you put it inside a black box; therefore it *may* not attract the negative attention of godlike acausal beings protecting causality, or in the absence of those beings, completely destabilize the timeline. I think it's possible that such a device violates the 2nd Law of Thermodynamics because of the way it processes information with zero loss, but I'm unsure of the extent of the raping without deeper thought.

2) Using a similar construction, you could send any information back through time. However, you would always need a receiver for the information to land in: either you could only send information as far back as the construction of the device, or you could only send it to other FTL receivers existing before the device's construction. This device is a total violation of causality, and use of such devices by more than one party could completely destabilize the timeline.

-A scanner that can observe without in any way interfering with the observed?
---What effect would it have if I could, say, determine precisely the position and momentum of a particle? How would quantum physics work (or not) with such tools?

This is actually a fatal violation of Physics, from our perspective. The Quantum Physics that allows chemistry to work is based on Planck's constant (h). With zero uncertainty in the universe, h is implicitly zero. This actually causes many disasters, but the first one to come to mind is that electrons will no longer reside in discrete energy levels (electron clouds) in atoms and will instead *actually* behave like planets in a solar system going around the nucleus. Since they are accelerating charges, they will radiate energy and quickly crash into the nuclei. One could wonder if they will combine with the protons to form neutrons (they won't), if indeed nuclei itself is in good shape (it ain't), if there are even protons there in the first place (fat chance), or if indeed you could even have photons with finite energy to observe any of this in such a universe (yeah right), but such speculation is at this point largely academic.

[Apollonius]

The question "what caused it?" would be meaningful for every single event in the universe, probably necessitating either that the age of the universe is infinite, or that it was created by a transcendent entity (a god), or that it was "born" from a universe that does know the concept of quantum uncertainty.

Your 'god did it' idea is utterly fucking stupid, as it always is and will be. You may as well have said "created by a giant magic fairy", as if that has any substance or credibility to explain fuck all about anything.

It's most probably wrong, and I don't subscribe to it (though I wouldn't call it stupid. Just because it's wrong doesn't automatically mean it's stupid). You're also right, that the concept of God doesn't explain anything in our universe, since we have discovered laws that make transcendent explanations superfluous. But it might have some merit as one of several possible explanations, in a universe that is thoroughly deterministic. So I put it there, along with some other alternative explanations that I could think of. If you can think of even more alternatives, feel free to add them. I'm sure they would work better than God.

No, experts are simply smart enough to understand the question has no meaning. It's like asking "What does hope smell like?", or "What is the colour of abstraction?", or "Why are Unicorns hollow?".

But apparently not smart enough to understand that this lack of meaning has to be conveyed to laypersons in a way they can understand it. Isn't that part of their mission? To not only accumulate knowledge for themselves, but to also share it with the public?
Don't be a prick by poking out your tongue at people who ask questions. It is not within your rights to capp people stupid, because they don't have the same knowledge as you. Questions such as "what was before the Big Bang" may not be meaningful inasmuch as they probably don't have a meaningful answer (note that some scientists speculate that time may very well have existed even before the Big Bang, there's even a relevant thread in this forum), but the question as such is far from being pointless. Please don't turn science into religion by forbidding us to ask questions.

[Ariphaos]

I'm assuming the same thing. Aside from allowing FTL travel that doesn't screw up causality (in principle at least), what would be the other effects of a universal frame of reference?

This is a tricky question. I can only speak a bit as to the scientific effects - the cultural effects were ones I spend more time pondering for Solar Storms and such.

The main thing that has to be remembered is the principle of relativity. This means that, at best, the ability to observe a special frame is just outside of our reach. At worst (assuming its existence), it's so far outside of our reach as to be impossible to utilize. For example, a collider capable of reaching "Theory of Everything" energy levels using reasonable magnetic limits would have a radius on the order of a parsec. If that's what it takes, it very likely isn't happening, though you could have a type ~2.5 civilization harnessing the power of giant stars to act as galactic radios. Such a situation would be hard to bring up a causality violation with even without a special frame, as moving such things at any significant velocity is not going to be feasible. There's also a significant question as to how much range such a radio would have.

You almost certainly can't avoid magitech even on the low end of the scale if you want a ship or even a planet with an ftl transmitter. I have a lot of fun with this in Solar Storms - the lives of the overwhelmingly vast majority of sentient beings are dominated by the laws of relativity.

Anyway, culturally, some notes.
1: People aren't going to rave about Einstein being wrong, any more than people rave about Newton being wrong. Whatever the situation, it's completely outside of Einstein's purview to observer. It would be like blaming 19th century geologist for thinking the Earth is an oblate spheroid instead of slightly egg shaped. They didn't have satellites and Einstein didn't have orbit-sized magnetic accelerators.
2: Time tracking is a problem that still vexes me a bit. You now have a situation where it's possible to directly ascertain an entity's proper time. You now have to track this separately from your own time in order to deal with people - everyone who makes use of ftl in a fixed frame needs two clocks, because living by the fixed frame clock is not necessarily feasible or useful for most local purposes.
3: How feasible it is, and such, is going to have a massive impact on galactic culture. If it's difficult and for the rich, neighboring systems are going to see their cultures diverge. In this case, what forms do FTL warfare take?

Perhaps if I rephrase it then: what would be the effects of being able to ignore the observer effect?

Besides congratulations on your amazingly accurate measuring device?

There are too many caveats here. How many hoops do you have to jump through to get this? Using a massive apparatus to track a single atom as much as Heisenberg allows is good for research, but where that research could lead is an open question.

The smaller the device and the greater its scope, the more useful it is as a real sensor of some sort, but you still don't describe it enough.

[Surlethe]

-A scanner that can observe without in any way interfering with the observed?
---What effect would it have if I could, say, determine precisely the position and momentum of a particle? How would quantum physics work (or not) with such tools?

It wouldn't work. The whole point of quantum mechanics is that you can't simultaneously precisely determine position and momentum -- the product of the uncertainty of momentum and the uncertainty of position is always h/4pi. That's an empirically established law, predicted by theory, just like Newton's third law or the constancy of the speed of light. In some sense, QM resolves the paradox of a point-particle (precise momentum and position simultaneously) by relying on the inability to experimentally determine precise momentum and position to mask a waveform: the particle is "smeared-out" probabilistically. It's a model that's produced exceedingly accurate predictions; if you handwave away the uncertainty principle, you handwave away all of QM and its confirmations, since QM predicts the uncertainty principle.

[Apollonius]

It wouldn't work.

Ah, but that's not the real question. I believe that Teleros is already aware that it wouldn't work in our universe, that's why he's doing science fiction, after all. It's all about an alternate universe. The really interesting question is: how would stuff work in a universe where quantum uncertainty doesn't exist? Would the implications affect macroscopic phenomena?

[Teleros]

It's most probably wrong, and I don't subscribe to it (though I wouldn't call it stupid. Just because it's wrong doesn't automatically mean it's stupid).

Just say "monads made it" instead of God next time .

There are too many caveats here. How many hoops do you have to jump through to get this? Using a massive apparatus to track a single atom as much as Heisenberg allows is good for research, but where that research could lead is an open question.

The smaller the device and the greater its scope, the more useful it is as a real sensor of some sort, but you still don't describe it enough.

First off, it's about as variable as say a camera, both in terms of how large / small it has to be and how good it is, and about as common-place, if not moreso. It's certainly used in sensors and the like, being able to detect both matter and energy (eg it could detect both a radar signal and a starship). I'm not so much interested in the social or cultural consequences (they're not so hard to imagine), but rather what it means to things like quantum mechanics etc (or, the hard stuff ).
As to how it works (beyond "it just does" ), the idea I had was that, rather than scanning the real universe, it scans a sort of mirror universe - that is, everything that happens in our universe is reflected in this other dimension, but not the other way around. The scanner can't change the mirror universe by scanning it, because to do that you'd need to change the real universe, which presumably wouldn't be happening with this scanner.
So, you could do the equivalent of bouncing photons off an electron all day, but without affecting it, because it's the mirror image of the real one. On the other hand, you wouldn't be scanning the real universe, so strictly speaking you wouldn't be able to "see" the real electron or whatever it is you're scanning... would quantum mechanics mind much, or am I still going to cause Strider's fatal violation of physics?

If such a method existed, one could construct two highly powerful super-devices

Hmm, hadn't realised the CTC or time-travel possibilities... scrap that plan for FTL comms then.

[Ariphaos]

First off, it's about as variable as say a camera, both in terms of how large / small it has to be and how good it is, and about as common-place, if not moreso. It's certainly used in sensors and the like, being able to detect both matter and energy (eg it could detect both a radar signal and a starship). I'm not so much interested in the social or cultural consequences (they're not so hard to imagine), but rather what it means to things like quantum mechanics etc (or, the hard stuff ).

As everyone has mentioned, the Heisenberg uncertainty principle is a fundamental property of the particles of our Universe. It's not going to see exactly where and how fast a given particle is moving because there is no such thing. What it actually does see is somewhat up to you, and explaining how it works may not be the best idea (since a cross-dimensional anything has other implications). One concern you may wish to think about is how much information it can store.

So, you could do the equivalent of bouncing photons off an electron all day, but without affecting it, because it's the mirror image of the real one. On the other hand, you wouldn't be scanning the real universe, so strictly speaking you wouldn't be able to "see" the real electron or whatever it is you're scanning... would quantum mechanics mind much, or am I still going to cause Strider's fatal violation of physics?

Again, you're not going to get a perfect picture of that electron.

Hmm, hadn't realised the CTC or time-travel possibilities... scrap that plan for FTL comms then.

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.

[Teleros]

Again, you're not going to get a perfect picture of that electron.

Well that's that cleared up at least .

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.

Yeah, I think I just went blank then for some reason .

[Singular Intellect]

The question "what caused it?" would be meaningful for every single event in the universe, probably necessitating either that the age of the universe is infinite, or that it was created by a transcendent entity (a god), or that it was "born" from a universe that does know the concept of quantum uncertainty.

Your 'god did it' idea is utterly fucking stupid, as it always is and will be. You may as well have said "created by a giant magic fairy", as if that has any substance or credibility to explain fuck all about anything.

It's most probably wrong, and I don't subscribe to it (though I wouldn't call it stupid. Just because it's wrong doesn't automatically mean it's stupid).

Then by all means explain where invoking any god concept has any intelligent aspect whatsoever, instead of just being an appeal to fantasy and ignorance.

You're also right, that the concept of God doesn't explain anything in our universe, since we have discovered laws that make transcendent explanations superfluous. But it might have some merit as one of several possible explanations, in a universe that is thoroughly deterministic.

Are you fucking retarded? You admit that invoking the god concept doesn't explain anything, and then turn around and say it is one of merely several possible explanations?

Let's be clear on one thing. Invoking god is no explanation whatsoever, and it is one of an infinite number of bullshit ideas that can be pulled out of anyone's ass and have the fictitious label 'explanation' slapped onto it.

So I put it there, along with some other alternative explanations that I could think of. If you can think of even more alternatives, feel free to add them. I'm sure they would work better than God.

I have a better idea: formulate theories and conclusions based on evidence and logic, don't waste time appealing to random ideas and fantasies.

If you're unable to do that, then do the intelligent thing and admit "I/we don't know".

No, experts are simply smart enough to understand the question has no meaning. It's like asking "What does hope smell like?", or "What is the colour of abstraction?", or "Why are Unicorns hollow?".

But apparently not smart enough to understand that this lack of meaning has to be conveyed to laypersons in a way they can understand it. Isn't that part of their mission? To not only accumulate knowledge for themselves, but to also share it with the public?

That's why we have things called books and education systems. They teach you the knowledge you need and desire without wasting any expert's time or effort unless they wish to devote it, therefore becoming teachers.

Any expert who gives you the time of day to explain their field and knowledge (having devoted their own time and resources to becoming said expert) is acting on courtesy, not an obligation.

Don't be a prick by poking out your tongue at people who ask questions. It is not within your rights to capp people stupid, because they don't have the same knowledge as you.

I suggest you read the board's motto. And for your information, I said the idea was stupid, I wasn't calling any one specific individual stupid.

Questions such as "what was before the Big Bang" may not be meaningful inasmuch as they probably don't have a meaningful answer (note that some scientists speculate that time may very well have existed even before the Big Bang,

So you're dealing with a universe where additional dimensions are not yet active, which is irrelevent. If the dimension of time exists, so does the universe, even if other dimensions are not yet apparent. The definition of the universe isn't some fucking on and off switch where it requires certain criteria. The definition merely requires the existence of anything.

there's even a relevant thread in this forum), but the question as such is far from being pointless. Please don't turn science into religion by forbidding us to ask questions.

No one has forbidden anyone to ask questions, liar. Stupid questions will simply be labelled as such.

I will say it again, proposing a question like "what was before time" is a meaningless and stupid question, and strawmanning the arguement by appealing to different models of the universe will not change that.

[Apollonius]

Are you fucking retarded? You admit that invoking the god concept doesn't explain anything, and then turn around and say it is one of merely several possible explanations?

Let's be clear on one thing. Invoking god is no explanation whatsoever, and it is one of an infinite number of bullshit ideas that can be pulled out of anyone's ass and have the fictitious label 'explanation' slapped onto it.

I don't believe that I'm retarded. But I do believe you missed something. I was speaking about a hypothetical universe, not about the one we live in. My apologies if that wasn't clear enough. Since we're debating science fiction in this thread, I think it is permissible to contemplate the possibility of a fictional universe in which a god exists. Why are you being so belligerent about this?

I have a better idea: formulate theories and conclusions based on evidence and logic, don't waste time appealing to random ideas and fantasies.

I thought this was about fantasy.

Any expert who gives you the time of day to explain their field and knowledge (having devoted their own time and resources to becoming said expert) is acting on courtesy, not an obligation.

That's certainly true. But it is also true that, while they have no obligation to do so, it would still be a good idea, if they want people to actually understand the answers they give. If you don't want to be understood, why bother giving a half-arsed answer in the first place? It just comes across as condescending, and - even worse - opens doors for misconceptions.

I suggest you read the board's motto. And for your information, I said the idea was stupid, I wasn't calling any one specific individual stupid.

Yes, indeed you didn't. My mistake.
I'm not so sure where you're getting at with your appeal to the board's motto. I always interpreted that to mean that you actually have to be stupid in order to be mocked. Now, I fully understand that you're being 100% convinced of my stupidity (and please excuse me if I'm just projecting now), but I'd like to ask you to please grant me the benefit of doubt. After all, I don't believe that, based on what I said in this thread, I really qualify as stupid.

No one has forbidden anyone to ask questions, liar. Stupid questions will simply be labelled as such.

Let's not split hairs now, please. I used the expression "don't forbid" in the colloquial sense, as in "don't ask us not to", or "don't deter us from", or "excuse us if we do". Since I'm fully aware that you're in no position to actually forbid it, how could I ask you to not do something that you, in fact, can't do in the first place? How this makes me a liar, even if I had used it in the literal sense, is beyond me, but you were probably just looking for further reasons to rip me apart... Quite understandable, since I seem to have upset you so much (for which I am honestly sorry (no sarcasm here, even if there admittedly was some earlier), since I never had, nor intended to have any quarrel with you).

I will say it again, proposing a question like "what was before time" is a meaningless and stupid question, and strawmanning the arguement by appealing to different models of the universe will not change that.

I totally believe you that it's meaningless. I reject, however, that it is stupid. It's only stupid if you already know why it is meaningless, and the answer really isn't that obvious, nor is it intuitive. In fact, I wouldn't even consider your extreme examples ("What does hope smell like?", or "What is the colour of abstraction?", or "Why are Unicorns hollow?") as stupid, since they can, under certain conditions, have meaningful answers (the first two immediately make me think of synesthesia).

I somehow suspect that I got the attention of your animosity because you wrongly believe that I'm trying to advocate god. I'm really not. I'm a honest-to-god atheist (weee, I get the prize for worst pun of the century), even though I gave up calling their beliefs stupid about a decade ago.

In any case, let's not hijack Teleros's interesting thread any more. I would edit my original post to stop it from offending you, if I could.
I you really feel the need to go on fighting, we should do that in a separate thread or PM, though I'd rather just bury the hatchet, with your permission.