Can "cause & effect" travel faster than the speed of light?

[nz1m]

A straw filled with air, sealed at both ends. I press on one end and the other end bulges. Or a stick. I move one end and the other end moves. The straw goes between here and the moon. I could tap out "hi" in morse code on my end of the straw. Would my "hi" reach the moon faster than a radio wave?

[RJN]

No. The fastest any information can move along the straw is the speed of light, and radio waves travel at the speed of light. Please see this discussion
here: http://asterisk.apod.com/vie ... 30&t=19641
and answer here: http://asterisk.apod.com/vie ... 30&t=19643 .

- RJN

[Beyond]

If you switch to photons the answer just may be yes. I ran across a couple of different discussions about an experiment that was done with a length of photons. The cause at one end was instantly felt as the effect at the other end.
Of course the length of photons is rather limited here on earth, but if it turns out that the cause and effect is instantaneously felt at both ends no matter how long the length, then it would seem as though it would be possible that given a long enough length, at some point the action of the cause and effect in photons would exceed the speed that light travels to get there.
This indeed would be most interesting if it turns out to be true and a way could be found to cause the photons to act as a viewing port and a connection could be found to the area of the beginning of the Universe.
It would seem to be most helpful if the beginning area could be viewed as it is - right now, today.
If the photon Genie could be rubbed the right way........who knows what it may lead to.

[Chris Peterson]

If you switch to photons the answer just may be yes. I ran across a couple of different discussions about an experiment that was done with a length of photons. The cause at one end was instantly felt as the effect at the other end.

You have to be careful how these sorts of experiments are reported. Although there are all sorts of tricky ways to apparently exceed c, nobody has actually managed to do it in a way that results in information being transferred faster than c.

[Beyond]

The articles that i read about the reaction of the photons emphasized that it was too short of an experiment to measure the speed of, but the focus was on the interesting reaction of the length of the photons themselves to re-act as a "whole" unit instantly. That realization in and of itself may have already caused inventive minds to start the thought processes going of how to use lenghts of photons in ways never thought of before. Of course on the more practical side of things actually getting done and being available for use - well....we may never see that for many lifetimes. But in the world of science who knows what an idea may spark? And if it turns out that photons have a faster reaction time then the speed that they can travel is -- so what? We just may find out that there is more to light than meets the eye.

[Henning Makholm]

The articles that i read about the reaction of the photons emphasized that it was too short of an experiment to measure the speed of, but the focus was on the interesting reaction of the length of the photons themselves to re-act as a "whole" unit instantly.

All the experiments of that sort I have read about always boil down to variants of the "EPR paradox", which follows the following general set-up: A random outcome of something that happens at time-and-place A "causes" an measurement at time-and-place B to match the outcome at A, where the interval between A and B is faster than light.

It is then always the case that if we analyze the situation in a moving frame where B happens before A (special relativity says we can always find such a frame), the very same experiment can be viewed as something random happening at B and afterwards the measurement at A happens to match that. The two analyses result in the same probability predictions for all combinations of what happens at A and B. Thus, it is in principle impossible to use the effect for FTL communications; it is not just a question of engineering or of getting the right idea.

Arguably, the apparent faster-than-light causation in these experiments are not so much a real property of the world, as a mathematical artifact of the way our theories describe the world.

(The most intuitively appealing resolution of these experiments is that the actual random choice happened earlier, such that information about its outcome had time to propagate to A and B at sublight speeds. However, there are clever variations of the experiment that rule out this possibility, which have actually been performed with the expected results).

[Beyond]

I do not know what "FTL" is, but it almost sounds like you are saying that sometimes an effect will happen at point A before the cause reaches point B ??

[Henning Makholm]

I do not know what "FTL" is, but it almost sounds like you are saying that sometimes an effect will happen at point A before the cause reaches point B ??

FTL = faster than light.

I don't know what you mean by "cause reaches point B".

I'm describing a certain class of experiments where things that happen at event A and things that happen at event B turn out to match each other in a certain well-defined way. If you're operating in a coordinate system where A takes place before B, you may want to call the thing that happens at A a "cause" of what happens at B shortly after. On the other hand, if in your coordinate system B takes place first, you could prefer to call B a "cause" and A an "effect". Nature doesn't mind what you call cause and what you call effect (because whatever you choose to call the "cause" is a random non-influencable event anyway), and the theory yields the same predictions in both of these cases.

[Beyond]

Oh....ok. So do you think that photons could have at least two operating modes? One at the speed of light or slower and an instantaneous reaction mode no matter how long the photon length?

[Henning Makholm]

Oh....ok. So do you think that photons could have at least two operating modes? One at the speed of light or slower and an instantaneous reaction mode no matter how long the photon length?

I'm not saying anything even remotely like that. I don't even have a good idea which statement of mine it is you're misunderstanding.

[Beyond]

I don't either. Somehow this conversation seems to have gone POOF into thin air. Maybe we should let it stay that way??

[StarstruckKid]

What about 'quantum entanglement' and 'gravity waves'?

The speed of sound in a medium such as air or water is the limit at which information can be transmitted from point A to point B, yet a beam of light can also pass 'through' the same medium at a much higher rate, leaving open the idea that some other mechanism could exceed the speed of light through the fabric of the cosmos.

We are stuck on light/electromagnetism because our senses and instruments can so easily detect it, but that does not mean no other transmission mechanism exists.

For instance, the poorly understood (and largely unproven) phenomena of telepathy and 'astral projection' are difficult to explain as electromagnetic in nature.

[Henning Makholm]

What about 'quantum entanglement' and 'gravity waves'?

Gravity waves, as predicted by General Relativity, travel at speed c.

Quantum entanglement is what I speak about in my posts of August 2, above. As long as the fundamental theory satisfies Lorentz symmetry (which every quantum theory that makes a claim for being fundamental does), it is relatively straightforward (assuming one knows already how such theories work) to argue that entanglement cannot be used to send information faster than c.

We are stuck on light/electromagnetism because our senses and instruments can so easily detect it, but that does not mean no other transmission mechanism exists.

No, but special relativity still forbids information from travel faster than c. It does not depend on light, but can derived simply from considering how the spacetime differently moving inertial frames fit together.

The basic postulate of special relativity is that there is some speed that all inertial observers measure to be the same. This invariant speed, named c, turns out to be the fastest that information can meaningfully be imagined to travel. The fact that light happens to travel at speed c through vacuum is convenient for practical measurement, but the theory would work perfectly well without it.

[Chris Peterson]

The speed of sound in a medium such as air or water is the limit at which information can be transmitted from point A to point B, yet a beam of light can also pass 'through' the same medium at a much higher rate, leaving open the idea that some other mechanism could exceed the speed of light through the fabric of the cosmos.

No, solid theory sets c as the limit for information transfer. It is important to realize that c is not the speed of light. It is a universal constant that shows up in many places. It happens that one of its most obvious physical manifestations is that it defines the speed of light in a vacuum. That is, c defines the speed of light, not the other way around.

[StarstruckKid]

My point was not about c versus the speed of light, or whether information can propagate faster than c; solid theory also says sound cannot travel faster that mach 1 in air, not to be too rigorous or to make that an analogy to c. It was, rather, to suggest, as a "thought experiment", that there may be some other mechanism that we are not aware of because neither we nor our existing instruments can detect it, and which is not addressed by the mathematics of relativity, that can 'bypass' or 'move through' space as we know it and is not bound by c, just as c is not bound by the speed of sound in air.

Our forebears were unaware of most of the electromagnetic spectrum, and many well-educated people would have vehemently denied the possibility of its existence, because neither they nor the instruments available to them could detect it.

We have some anecdotal evidence of the phenomenon of telepathy, but we cannot reliably sense it, nor do we have instruments which can detect it, so it remains in the the realm of conjecture, and many smart and well-educated people will vehemently deny its possible existence. I don't claim to know myself. But I do know that when I was old enough to be learning about such things, what we now know as 'plate tectonics' was called 'continental drift' and was derided and scorned by, again, some very smart and well-educated people.

One thing we know for sure: we don't know what we don't know!

[Chris Peterson]

My point was not about c versus the speed of light, or whether information can propagate faster than c; solid theory also says sound cannot travel faster that mach 1 in air, not to be too rigorous or to make that an analogy to c. It was, rather, to suggest, as a "thought experiment", that there may be some other mechanism that we are not aware of because neither we nor our existing instruments can detect it, and which is not addressed by the mathematics of relativity, that can 'bypass' or 'move through' space as we know it and is not bound by c, just as c is not bound by the speed of sound in air.

Well, a thought experiment must be defined within the bounds of existing theory. Otherwise, it has no meaning. And within current theory, information can't be transported faster than c. If you want to suggest something completely outside of theory, and which we are completely unaware of, you might as well suggest that information could be carried instantaneously by little green fairies.

Is it possible our fundamental ideas about relativity are wrong? Yes. Is it likely? No.

[Henning Makholm]

My point was not about c versus the speed of light, or whether information can propagate faster than c;

Um, I fail to grasp the difference between "whether information can propagate faster than c" and the topic you aver to be discussing instead. Could you please explain more clearly why your speculation is not about "whether information can propagate faster than c"?

If you're merely speculating about an unknown effect that would propagate at or slower than c, then why are you doing it in this thread at all?

[swainy (tc)]

Quantum entanglement

Can some body please explain to me, how Quantum Entanglement Works I think it involves dual electrons, and those Electrons synchronized together, no matter how far apart they still move when the other moves. But How can they do this instantly? What connection do they still have? Thanks

tc

[Chris Peterson]

Can some body please explain to me, how Quantum Entanglement Works

Have you read the Wikipedia article on the subject? It's pretty good.

There is no problem with things operating instantly over a distance as long as no information is transmitted- which happens to be the case here.

[swainy (tc)]

There is no problem with things operating instantly over a distance as long as no information is transmitted- which happens to be the case here.

1's And 0's Chris Its moving 1 Its not moving 0. How did you get this message from me? Was it not 1's And 0's ?

tc

[bystander]

Can some body please explain to me, how Quantum Entanglement Works I think it involves dual electrons, and those Electrons synchronized together, no matter how far apart they still move when the other moves. But How can they do this instantly? What connection do they still have?

It is my understanding that Quantum Entanglement does not necessarily involve electrons, nor even pairs. It is a property of a system involving two or more like quantum particles and/or anti-particles (photons, protons, atoms, etc) such that the state of any one particle in the system can not be fully described without the consideration of all the particles in the system. That is to say, if the state of one particle is known, the states of all particles in the entangled system are known, regardless of the distance between particles.

As to how this happens, Einstein derisively called it "spooky action at a distance". Way too deep for me and I didn't bring my waders.

[Chris Peterson]

1's And 0's Chris Its moving 1 Its not moving 0. How did you get this message from me? Was it not 1's And 0's ?

?????

[swainy (tc)]

It is my understanding that Quantum Entanglement does not necessarily involve electrons, nor even pairs. It is a property of a system involving two or more like quantum particles and/or anti-particles (photons, protons, atoms, etc) such that the state of any one particle in the system can not be fully described without the consideration of all the particles in the system. That is to say, if the state of one particle is known, the states of all particles in the entangled system are known, regardless of the distance between particles.

Interesting that. Cheers Bystander. Gimme somot to think about that has. Nice One.

swainy (tc) wrote:1's And 0's Chris Its moving 1 Its not moving 0. How did you get this message from me? Was it not 1's And 0's ?

?????

That's how your pc works Chris. 1's and 0's . Its either on or off. same, which could make instant Quantum Entanglement chat, galaxy wide? or help us peer into the unknown?

tc
tc

[Chris Peterson]

That's how your pc works Chris. 1's and 0's . Its either on or off. same, which could make instant Quantum Entanglement chat, galaxy wide? or help us peer into the unknown?

No. It has been pretty well shown that you can't use quantum entanglement to actually transmit information. It doesn't matter whether you want to associate binary with spin, or use some other encoding. Trying to send information effectively results in random results.

[Beyond]

I don't think that particles have the three gates needed to send 1's and 0's . That would be the - and, or and nor gates.