1. I think the confusion lies therein that Faultline thinks he can force a state. If he could force a state, he could communicate. But you can not force a state, therefore you can not communicate.

2. I guess there's no way to observe the affect of one without changing the spin of the other. So when the two particles are generated, it would be impossible to know which ship got the up spin and which ship got the down spin.

If it were possible to know which ship got which spin before observing them, then you could have one ship observe theirs at a distance of 1 ly from the other, and the other ship could check theirs and find they had the opposite from which they started out.

It would then be a simple "1" or "0" binary message. Like I said, 1 if by land, 2 if by sea.

I think I understand better now.

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My question is this, regardless of whether you can transmit usable information, the mere fact that instantaneous reaction occurs violates causality by these guidelines. In the same example the link gave 4 people and 4 "asnibles" with 2 parties in seperate time frames, you could notify one party before the first party transmits. The fact that we can't measure its state readily, doesnt mean that the state hasnt changed. So back to square one, if this is a proven fact, then causality has been disproven. How does GR or SGR explain an "instant" reaction regardless of distance and time frame?

4. Originally Posted by Faultline
I think I understand better now.
I think you are, but there are still a couple things that are misleading in your statement.

Originally Posted by Faultline
If it were possible to know which ship got which spin before observing them, then you could have one ship observe theirs at a distance of 1 ly from the other, and the other ship could check theirs and find they had the opposite from which they started out.
I can see two separate problems with this. One is that you're imagining that measuring one of the particles necessarily flips the other one. That's not really the case, even if we were imagining that the spin of the two particles was a real attribute that could be said to have a value before being measured. In that case, one would just be spin up and the other would be spin down, and we still wouldn't be able to use that for communication.

But the more important result from all this is that it's meaningless to speak about which ship got the spin up quark and which the spin down quark. Until we've measured the spin of one of them, it has no definite spin. It's not just that we don't know which way its spin is oriented, its that the particle itself doesn't know which way its oriented.

5. Originally Posted by 0Kelvin
My question is this, regardless of whether you can transmit usable information, the mere fact that instantaneous reaction occurs violates causality by these guidelines. In the same example the link gave 4 people and 4 "asnibles" with 2 parties in seperate time frames, you could notify one party before the first party transmits. The fact that we can't measure its state readily, doesnt mean that the state hasnt changed. So back to square one, if this is a proven fact, then causality has been disproven. How does GR or SGR explain an "instant" reaction regardless of distance and time frame?
It does and it doesn't. As I said, I think Einstein would have been really unhappy with the resolution. That is, EPR assumed locality to show that quantum mechanics must be incomplete, that there must be some hidden variables underlying quantum theory that might behave in a more orderly, deterministic fashion, and get rid of the whole quantum randomness issue. However, it looks instead like the question of hidden variables remains an open one (though most physicists think it unlikely), and instead locality has been shown to be false. In some sense, we know that the universe does not obey causality in the sense that we normally think of it.

However, the influence that travels at superluminal speed is forever hidden in quantum randomness. You said, "The fact that we can't measure its state readily, doesnt mean that the state hasn't changed", but this is precisely the point. In quantum mechanics, if you haven't measured something, it doesn't have a value. Let me say that again. The state hasn't changed, because it didn't have a value until you decided to measure it. Relativity doesn't have a problem with this, since, technically, no information was sent. That seems like a loophole, but it apparently works out.

Quantum mechanics and special relativity work fine together with this realization (the math all works out, we can make predictions that agree with experiment to amazing precision), it's just that the laws of nature don't seem to follow common sense. Or even follow the weird non-common sense that was relativity without quantum theory. As Niels Bohr said, "Anyone who is not shocked by quantum mechanics hasn't understood it".
Last edited by Grey; 2005-Nov-01 at 03:09 AM.

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So the loophole between quantum mechanics and relativity is simply, "Perception is reality”? This can give you quite a headache! Einstein believed that there was a simple elegance to the universe . Quantum theory shouts the universe is ugly, chaotic and very temperamental . Yet some how we manage to cope with the two in a twisted dysfunctional relationship in order to understand the universe around us. A spooky action, which can be proven violates the basics of Relativity, so we use semantics to ignore this discrepancy. That’s it I have made up my mind. I’m going back to school, and then I am going to postulate a Unified Theory =). I think it is the only thing that will cure this migrane!

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Maybe asprin would be easier?

8. Originally Posted by 0Kelvin
Maybe asprin would be easier?
Yes, I think so. Though coming up with a unified theory of quantum gravity would be more helpful to the rest of us. Still, there's one thing I'd suggest. It's true that the world as described by quantum mechanics is weird, and the reality we think we know seems to be supported only by chaos and illusion. Still, I think it has a certain elegance and beauty of its own.

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Originally Posted by Grey
[snip]
Still, I think it has a certain elegance and beauty of its own.
Oh yes, that it most certainly does!

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## re: "spooky action at a distance"

Somewhere I read the Bell instantaneous connections referred to as "God's Phone Lines". I can't, for the life of me, remember where I heard this reference. Can anyone clue me in where I might go about finding a reference to this terminology in a book or article? It might sound "off the wall", but the reference in important to an article I'm preparing linking shamanism to quantum theory.

11. ## rai linga

Originally Posted by rai linga
... the reference in important to an article I'm
preparing linking shamanism to quantum theory.

BTW

12. Originally Posted by rai linga
Somewhere I read the Bell instantaneous connections referred to as "God's Phone Lines". I can't, for the life of me, remember where I heard this reference. Can anyone clue me in where I might go about finding a reference to this terminology in a book or article? It might sound "off the wall", but the reference in important to an article I'm preparing linking shamanism to quantum theory.
Welcome to the board. I'm afraid the reference doesn't sound familiar at all, and Google is of no help. I'll echo Halcyon's thoughts about a potential link between shamanism and quantum theory, though, I'm afraid.

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I realize I'm posting kind of late on this, but to anyone still confused as to why quantum entanglement doesn't allow faster then light communication, here's why:

So, lets say you and your friend each have a particle and they are coupled with each other. If you should measure your particle, it will either end up in state #1 or state #2. Now, because they are coupled if you measure yours to be in state 1 you KNOW that the other one has to be in state 2! (Of course, this is nothing that wasn't already said in this thread. just stating the obvious here).

So, with your newly coupled particles you and your friend each get in your spaceship and fly 1 light year apart. Before leaving, however, you agree that observing state 1 means "I'm happy" while observing state 2 means "I'm sad" (cheesy, I know, but bear with me). You also agree that YOU will be the one observing your particle first so that you can send information to your friend about what mood your in.

Now, with you sitting at 1 ly distance from your friend, your feeling quite sad so you want your particle to be in state 1 so that your friend will observe state 2 and know that your sad. So, you observe your particle and...............well, it now has a 50/50 shot of ending up in state #1. There's no way for you to force it into state #1, and so when your friend observes his particle, he will see simply a random state. Even though he will know what state your particle is in 1 ly away, he will have no way of knowing if it was the state you wanted it to be in. You where not able to send him any information.

Keep in mind that the entire reason this doesn't allow communication is because you can't choose what state the quantum particle falls into. If it where possible to pick it's state, which would decide the state of the other particle, then YES, this idea would work. If we could control quantum coupling, by looking at my half of the particles I would know what you where trying to tell me and we would have instant communication (cumbersome perhaps, but instant). However since we can't do this, we also can't send any information this way.

Here's another way to look at it:

Lets say before you set out, instead of being given 2 particles, you where each given a sealed envelope. Inside one had the #1 written on it and inside the other had the #2 written on it. All the same rules apply.

Once you get to 1 ly apart, by opening up your envelope and seeing that you where given the #1 envelope your IMMEDIATLY know that 1 ly away there is an envelope with the #2 written inside it. WOW!!! Did information just travel faster then the speed of light? How is it that you are able to know instantly the state of something 1 ly away? Unfortuantly, you having the #1 envelope and your friend having the #2 envelope doesn't allow you to communicate instantly with each other, regardless of how many pairs of envelopes you have and in what complex arrangement you decide to open them. Simply observing that you have the #1 envelope doesn't even tell you weather your friend is even looking at his right then, if he alread has looked or even if he will. Indeed, your friends ship might have been ambushed and destroyed by the evil Zurg empire and your envelopes would not behave any differently.

Just a note about the above example (for anyone familar with quantum theory), I know that quantum coupling is a little different then the example with envelopes since the envelopes had a pre-defined state and the quantum pairs do not. However, you can no more influence the quantum state anymore then you can get the envelope you have to read #2 instead of #1, and that's why I used that analogy.

14. That's the best analogy I've heard to date. Thanks.

15. Originally Posted by Faultline
That's the best analogy I've heard to date. Thanks.
I'd say yes and no. It explains why you can't use entanglement to communicate, but the analogy fails to show why the connection is peculiar in the first place. In particular, certain types of measurements end up too well correlated on the two ends to happen without superluminal communication, even though the individual results are always random if you restrict yourself to looking at the results on one side or the other.

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