Transferring information faster than light?

Zacharine

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Three Eyed Cyclops said:
Just because he was Einstein doesn't mean that he was right about everything.
Well, duh. Newton was an alchemist and an astrologist, that doesn't mean the Sorcerer's Stone is real or that the stars can predict your future.

Reading comprehension... buy yours today! Because nowhere did I say that QM is BS, only that Einstein thought it so and then by logical inference that his theories about Space-time and relativity were made while ignorant of the world of QM and the later experiments in that area.
 

crimson5pheonix

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angelzsniper said:
hittite said:
Okay, so assuming that you've set up a quantum link between two separate areas. Information can now be sent back and forth in real time, no matter how far apart they are. Assume also that you have perfected an Alcubierre warp field to the point that you can manipulate the size of the exterior without changing the interior (much like the Doctor's tardis). It may be possible to shrink it to the size of a Planck length and use it to ride the information from one location to another.
Star Trek? Anyway, I don't know why Planck length would even fit in this situation.
Necator15 said:
That's pretty close, but it has to be a pair of particles. (Every particle is created together with it's respective anti-particle for instance every proton is made with an anti-proton, every electron with a positron and so on and so forth) Each of the particles will have the opposite spin (That's why they're anti with respect to each other) and will always be opposite each other.
My. Head. I'm like googling half this stuff to figure out what you guys are talking about.
You really shouldn't. It's not good for your health.
 

Necator15

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angelzsniper said:
My. Head. I'm like googling half this stuff to figure out what you guys are talking about.
If you want something clarified, it'd probably be easier to just ask. Google (Hell wikipedia) have very ridiculous explanations for stuff like this. It can be pretty hard to wrap your head around.
 

Koloman Varady

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I don't know how well I can answer this but I'll give it a shot.

In a classical string, the speed of the wave pulse is proportional to the square of the tension (if I recall correctly) ie. if you quadruple the tension, you double the velocity. So yes, there is a relation between how much you stretch a string and how fast the pulse travels. But the string is made out of relativistic particles who are bumping into each other to make the wave propagate and if those particles can't move faster than the speed of light then it's pretty clear that the pulse won't move faster than the speed of light either.

The concept of velocity for a wave isn't all that straight forward, unfortunately. Check out this applet, for example http://galileoandeinstein.physics.virginia.edu/more_stuff/Applets/sines/GroupVelocity.html

The phase velocity is the speed at which individual peaks move and this can actually be made faster than the speed of light. Unfortunately, that turns out to not be at all useful for sending information. Information is usually a pulse or any discontinuity (ie. for me to be able to send useful information, it has to be something you don't know about ahead of time) and that travels at what is called the group velocity, which is never faster than the speed of light.

There is some muddy waters about faster than the speed of light velocity when it comes tunneling. It's possible for particles to tunnel through barriers or light to travel through some materials... that might be faster than the speed of light. My roommate is doing some research in the area (we share supervisors, so he's not that far out of my own field) and from what I've talked to him it's mostly an issue of there are situations where formulas about velocity may or may not apply and people are haggling about it and putting out new formulas and no one yet knows what is what. The point is that it's not well understood.

Quantum entanglement is another way I know of that can tell you information about something faster than the speed of light but it is impossible to use for communication. It's still eerie though and bugged the hell out of Einstein (for example, see the EPR paradox).

Edit: *grumble grumble* As someone linked, group velocity can exceed the speed of light (in highly dispersive media, where it is rather poorly defined - see above me mentioning that definitions of speed can become muddy). The signal velocity never exceeds the speed of light though (and that's the speed that a discontinuity travels at). If that's not enough, I'm pretty sure I can dig up a paper with at least 3 more definitions of velocity.
 

Zacharine

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crimson5pheonix said:
angelzsniper said:
hittite said:
Okay, so assuming that you've set up a quantum link between two separate areas. Information can now be sent back and forth in real time, no matter how far apart they are. Assume also that you have perfected an Alcubierre warp field to the point that you can manipulate the size of the exterior without changing the interior (much like the Doctor's tardis). It may be possible to shrink it to the size of a Planck length and use it to ride the information from one location to another.
Star Trek? Anyway, I don't know why Planck length would even fit in this situation.
Necator15 said:
That's pretty close, but it has to be a pair of particles. (Every particle is created together with it's respective anti-particle for instance every proton is made with an anti-proton, every electron with a positron and so on and so forth) Each of the particles will have the opposite spin (That's why they're anti with respect to each other) and will always be opposite each other.
My. Head. I'm like googling half this stuff to figure out what you guys are talking about.
You really shouldn't. It's not good for your health.
Oh please, this stuff is easy. It really gets fun only when you begin to contemplate why macroscopic objects do not spontaneously time-travel into the past, because strictly speaking no law of physics makes it impossible.
 

crimson5pheonix

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SakSak said:
crimson5pheonix said:
angelzsniper said:
hittite said:
Okay, so assuming that you've set up a quantum link between two separate areas. Information can now be sent back and forth in real time, no matter how far apart they are. Assume also that you have perfected an Alcubierre warp field to the point that you can manipulate the size of the exterior without changing the interior (much like the Doctor's tardis). It may be possible to shrink it to the size of a Planck length and use it to ride the information from one location to another.
Star Trek? Anyway, I don't know why Planck length would even fit in this situation.
Necator15 said:
That's pretty close, but it has to be a pair of particles. (Every particle is created together with it's respective anti-particle for instance every proton is made with an anti-proton, every electron with a positron and so on and so forth) Each of the particles will have the opposite spin (That's why they're anti with respect to each other) and will always be opposite each other.
My. Head. I'm like googling half this stuff to figure out what you guys are talking about.
You really shouldn't. It's not good for your health.
Oh please, this stuff is easy. It really gets fun only when you begin to contemplate why macroscopic objects do not spontaneously time-travel into the past, because strictly speaking no law of physics makes it impossible.
Or how variances in surface structure can bend light around an object to make it invisible.
 

Zacharine

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Necator15 said:
angelzsniper said:
My. Head. I'm like googling half this stuff to figure out what you guys are talking about.
If you want something clarified, it'd probably be easier to just ask. Google (Hell wikipedia) have very ridiculous explanations for stuff like this. It can be pretty hard to wrap your head around.
Also, QM and various fun bits and other stuff made easy in video format:

http://www.youtube.com/user/Best0fScience
 

Necator15

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What's really interesting would be thinking about ways that the observable universe would have more matter in it than anti-matter. They're both created at the same time in the same way, so there's very little reason why one would outweigh the other, but lo-and behold they do (To the best of our knowledge)
 

Altorin

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angelzsniper said:
hittite said:
Okay, so assuming that you've set up a quantum link between two separate areas. Information can now be sent back and forth in real time, no matter how far apart they are. Assume also that you have perfected an Alcubierre warp field to the point that you can manipulate the size of the exterior without changing the interior (much like the Doctor's tardis). It may be possible to shrink it to the size of a Planck length and use it to ride the information from one location to another.
Star Trek? Anyway, I don't know why Planck length would even fit in this situation.
Necator15 said:
That's pretty close, but it has to be a pair of particles. (Every particle is created together with it's respective anti-particle for instance every proton is made with an anti-proton, every electron with a positron and so on and so forth) Each of the particles will have the opposite spin (That's why they're anti with respect to each other) and will always be opposite each other.
My. Head. I'm like googling half this stuff to figure out what you guys are talking about.
the really "Ow head" thing to know is, is that if the spin of the particle changes, the other particle, if observed, will change at the exact same time as the first particle without ANY intervening interaction. Even if they're on opposite sides of the universe.

It's sort of like, if you change one, the other will act like it was changed the whole time.. due to the constraints of studying particles that small, we don't even see the change. It just is different. There are some really trippy quantum mechanic rules as to what you can and can't measure in quantum measurements. For instance, you can't measure a particle's spin, its position, and its velocity.. you can only measure one of them. If you measure any one of them, the other two can't be measured at the same time.

Or at least that's how I understood it when I read Brian Greene's book
 

Three Eyed Cyclops

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Hopeless Bastard said:
They've gotten light to exceed the speed of light. http://news.bbc.co.uk/2/hi/science/nature/841690.stm

Of course, that was ten years ago, I have no real idea whats happened since. Google fails me, as journalists hate writing retractions.
I hunted down the article and some of the papers that have referenced it (over 500 papers have been published since this was that have cited it). Although I did not extensively look, I found no retractions about it, but I did find lots of interesting articles to read.
 

Eclectic Dreck

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angelzsniper said:
Science! It makes me confused. I know nothing can travel faster than light since E=MC^2, C is the speed of light and as you reach the speed of light, the energy it takes to accelerate the mass becomes infinite. But can someone explain why this doesn't work.
Let's say for example that you have a length of a string, you hand your friend one end and keep the other end. You each go to other sides of the room. If you tug on the string, I can only expect the other side tugs at the exact same time (assuming the string is already stretched to its full capacity)

So will you be able to take something like this into a much larger scale (doesn't have to be a string) in which you pull/push on something and it happens somewhere else a few lightyears away? Just something to think about...

(1st post by the way :D)
As mass increases, the energy required to accelerate an object increases. As mass trends towards infinity, so does the energy required to further accelerate. Thus, as near as science can tell, nothing with MASS can travel faster than light. There are lots of caveats however - space appears to expand faster than light, quantum enganglement implies that there is SOMETHING that propogates faster and so forth. At the ragged edge of our knowledge of physics, the universe is a wierd place.
 

Necator15

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Altorin said:
... For instance, you can't measure a particle's spin, its position, and its velocity.. you can only measure one of them. If you measure any one of them, the other two can't be measured at the same time.

Or at least that's how I understood it when I read Brian Greene's book
You can measure more than one, but the degree of accuracy rapidly shrinks. (I could dig and find the equation in my old notebook, but that'd be a bit of a long search and the question will be irrelevant by than.)
If you try to measure all three to 100% accuracy you'll find it impossible, but if you're willing to settle for about 50% accuracy, you can measure two pretty accuratelyish.
You really can only measure one to 100% accuracy, and even then, it's more like 99%.
It's called Heisenberg's Uncertainty principle.

Following that, Schroedinger (There's an umlaut in there, but I can't do that on my keyboard) had the idea of you can't measure anything without effecting it. (This really only applies in quantum mechanics, but people constantly apply it to other, less relevant things)
 

Koloman Varady

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Necator15 said:
You can measure more than one, but the degree of accuracy rapidly shrinks. (I could dig and find the equation in my old notebook, but that'd be a bit of a long search and the question will be irrelevant by than.)
If you try to measure all three to 100% accuracy you'll find it impossible, but if you're willing to settle for about 50% accuracy, you can measure two pretty accuratelyish.
You really can only measure one to 100% accuracy, and even then, it's more like 99%.
It's called Heisenberg's Uncertainty principle.

Following that, Schroedinger (There's an umlaut in there, but I can't do that on my keyboard) had the idea of you can't measure anything without effecting it. (This really only applies in quantum mechanics, but people constantly apply it to other, less relevant things)
Don't really have to dig, Wiki's got the formula http://en.wikipedia.org/wiki/Uncertainty_principle

(uncertainty in the position) x (uncertainy in momentum) >= Planck's constant / 4pi

Because Planck's constant is very small, you have to get to very small lengths for this to crop up.

Spin does have some uncertainty relationships but I don't know of any between spin and momentum/position (just to clear that up, I think someone might have implied there is).

One way to make peace, to an extent, with quantum mechanics is to approach it as that instead of the formulas describing one system they describe an infinite 'ensemble' of systems performing the experiment at once. The equations then tell you what % of systems go into which state. This sort of things clears up things like Shrodinger's cat (which isn't half alive and half dead but half of an infinite amount of cats are dead and half of an infinite amount of cats are alive).
 

Necator15

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Hadn't occurred to me to check the wiki on that one.

My interpretation of the Cat thought experiment was the the cat was alive, dead, both, and neither at the same time until it was observed, at which point one has 100% probability and the other three drop to 0. Which is how computer scientists are attempting to create quantum computers by being able to have a bit that is theoretically in four states at once.
 

-AC80-

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if we had information that can go half the speed of light (eg downloading a internet vid) we would be getting about 1gb+++++, i imagine info at half the speed of light would be far faster. we dont really need to go faster than light but a way of extracting that info and spreading and decoding it will cost more than i can imagine.
 

Koloman Varady

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That interpretation has trouble (I think that's the one they call the Copenhagen interpretation) because the whole "observing" thing is pretty weird. Not only does it raise weird questions about what is an observer (if you observe something, is it still in a superposition until I observe it? does it have to be human? does it need a PhD in physics?) but the whole process of the "collapse of the wavefunction" isn't even a process that can be described by Shrodinger's equation (which describes quantum mechanics).

Even for a quantum computer I believe they rerun it several times until they can be sure of what is the correct answer (because of the statistical nature of the result, it can return different things). And neither isn't a valid state - the state has to be something.. it can't be 0, heh, else the thing would disappear (there's only 3 states in a quantum computer: 0, 1, 0 and 1).
 

Regiment

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Eclectic Dreck said:
As mass increases, the energy required to accelerate an object increases. As mass trends towards infinity, so does the energy required to further accelerate. Thus, as near as science can tell, nothing with MASS can travel faster than light. There are lots of caveats however...
You can see one of the caveats right now. The photons leaving your monitor are particles traveling at the speed of light, and they're naturally massless.

Theoretically, tachyons travel at the speed of light or more, and may travel backwards in time. Then again, so may antiparticles.
 

Necator15

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Tachyons actually can't travel below the speed of light.

I hadn't heard of any antiparticles that could travel faster than the speed of light, but that may be a "as of yet" bit for education.

As far as I can tell, the speed of light is a horizontal asymptote for just about anything other than a photon. Either the particle goes faster than it, or slower than it, it won't go the speed of light.
 

The Singularity

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That string is a ton slower than anything close to light. And by the way some things* are faster than light. Black holes trap light, yet Hawking radiation gets out, Dark energy, Dark mass, and gravitons can all escape black holes while light cannot.
*most of these things are...only theories and will be basically forever.

Space is insanely messed up and confusing, do not try to outsmart either Einstein or Hawking or you will get owned. For example, a wheelchair bound man discovered that Black holes, something never seen or proven, bleed radiation. "There are two things that are infinite, space and human stupidity, and I'm not sure about the former" Einstein.
 

Malcheior Sveth

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I think Tachyons are the only particles predicted to violate locality, and they aren't even meaningful physical objects. They just show up in a nice way in the mathematics of the Standard Model but they aren't necessary.

Beyond that, none of the quantum effects that have do have information traveling faster than the speed of light can exist for a long enough time (at least in (3,1) space, I dunno about (2,2) twistor space[black holes]). Any particle that is not on mass shell or photon that is not on the light cone will decay in < O(10^-23) time, AND we cannot see these "virtual particles"; they are basically what we think happens in the middle of an interaction, and all we see from that are what goes in and what comes out. Only real particles come out, and only those can travel any meaningful distance.

As for quantum entanglement, in theory it doesn't happen on a large enough scale to be useful, although at what point things stop being superpositions of probabilities (i.e. operating by quantum mechanics rules) and become normal macroscopic objects (i.e. operating by classical laws) is still an open problem in quantum mechanics.