[Jimbee (OP)]

Einstein called quantum entanglement "spooky action at a distance". I certainly don't understand it. Maybe people like Einstein really didn't either.

Anyways, it basically says one particle can affect another particle no matter how far away. One particle twists to the left, so does the other one, and vice versa. Instantaneously. My question is, could it be used to things like interstellar communication? Using just one pair of particles, you could have something like Morse code going. Or if you have enough particles working at the same time, you could have thousands, maybe millions of messages sent. Maybe they could all form pixels on a computer screen, or something like that.

But is it possible?

[paul cotter]

Bottom line is "you cannot transmit information faster than light". Don't ask me to explain, I can't, but I have seen arguments that are rock-solid and I am convinced. Not a very helpful answer, I realise. Halc or Origin would give you a rigorous answer.

[Origin]

Einstein called quantum entanglement "spooky action at a distance". I certainly don't understand it. Maybe people like Einstein really didn't either.

Einstein, Podolsky and Rosen came up with the thought experiment in which they proposed quantum entanglement, the purpose was to show that quantum mechanics must be wrong or incomplete.  What they actually did was to add more support to the theory of quantum mechanics.

My question is, could it be used to things like interstellar communication?

No, you cannot send any useful information using entangled particles.
Let's say I have an entangled particle and I am on a space ship 10 ly away from earth and back on earth you have the other entangled particle.  Neither particle has a defined orientation, they are both in a superposition state.  If I measure the particle as being 'up' then I immediately know the other particle is 'down'.  Since I had no idea what the orientation was before I measured the particle there cannot be any information other than the other particle is in the opposite direction.  In other words when I measure the particle the orientation is completely random and when the person back on earth measures the particle the results will be completely random.  The only thing I can know is the random results I got means the other particle will have an opposite orientation.  Each person will only see a random result, even though there is correlation between the 2 particles.

[Petrochemicals]

It is impossible, but so was the splitting of the atom, flight, etc.

If you have 2 particles and you give one to your accomplice to go on their light speed ship, if they conveyed information to you from 1LY, it would only be at the speed of light, you could have garnered the information yourself if you went on their ship at the speed of light. I do not see you knowing information that you could have discovered yourself at lights peed a problem

If precisely 1 year after your accomplice departed, another conspiritor from 1LY the opposite direction to that of your accomplice arrives bringing an entangled particle, you and likewise your explorer accompice would know what was going on in either direction but you would know the information if you had travelled to the lication and so could your accomplice. I do not know whether this is a problem or not.

The conspiritor and their particles  would however would be privvy to information that would take another year to reach them. They could not have travelled 2 light years from their start point in 1 year.  This would suggest it is impossible.

[Origin]

If you have 2 particles and you give one to your accomplice to go on their light speed ship,

It is not possible for a ship to go light speed but we can assume it is possible.  Let's call this accomplice Jim.
 

if they conveyed information to you from 1LY, it would only be at the speed of light, you could have garnered the information yourself if you went on their ship at the speed of light.

Ok so Jim who is one ly away sends a signal, I can:
1.  Wait a year for the signal.
2.  Fly to the Jim at light speed and ask what was in the signal, which would take a year.
3.  Fly in my ship towards Jim at light speed and intercept the signal in 6 months.

Where do the entangled particles come in?

If precisely 1 year after your accomplice departed, another conspiritor from 1LY the opposite direction to that of your accomplice arrives bringing an entangled particle,

Let's call the new conspirator Bob.
So when Jim is one light year away, Bob shows up having flown one ly from the opposite direction.  He has an entangled particle.  I have no idea what this new entangled particle has to do with anything.

you and likewise your explorer accompice would know what was going on in either direction

Who is the explorer accomplice (Jim I assume)?  What is it that we would know 'is going on'?

but you would know the information if you had travelled to the lication and so could your accomplice.

What information?  The signal?  So after 1 year both Bob and I would know the contents of the signal sent by Jim.  That is correct if that is what you are saying. 
I don't see how this has anything to do with entanglement.

[paul cotter]

Origin, while I agree 100% with the thrust of your argument I offer one small correction: If YOU travelled to jim  at light speed, surely it would take zero time while jim would see it as taking I year?   

[alancalverd]

Neither particle has a defined orientation, they are both in a superposition state.  If I measure the particle as being 'up' then I immediately know the other particle is 'down'.  Since I had no idea what the orientation was before I measured the particle there cannot be any information other than the other particle is in the opposite direction.

Now force your particle into an up state:  you therefore know mine is down, and I can measure it.

If you want to tell me something, flip your particle. Mine will "suddenly" (the question is how suddenly) flip, so you have sent me information.

[paul cotter]

Don't think so, Alan, but I am not good enough( not good at all! ) on quantum phenomena to counter your scenario. Offhand I reckon you would break the entanglement by forcing a state on your particle. If one could do that the other particle would follow instantly.

[Origin]

Origin, while I agree 100% with the thrust of your argument I offer one small correction: If YOU travelled to jim  at light speed, surely it would take zero time while jim would see it as taking I year? 

You could be right, his example was rather hard to follow.  My take is that when Jim sends his signal Bob had just arrived and he and I are at the same place so we would get the signal at the same time.

[Origin]

Now force your particle into an up state:  you therefore know mine is down, and I can measure it.

It is impossible to force a superposition particle to be measured in the up (or down) position.  The position is always random.  If it were possible to force the position, you could communicate information but that is not possible.

If you want to tell me something, flip your particle. Mine will "suddenly" (the question is how suddenly) flip, so you have sent me information.

Once either particle is measured they are no longer entangled so flipping one of the particles after the initial measurement has no effect on the other particle.

[Halc]

Don't think so, Alan, but I am not good enough( not good at all!

No, you very much are good enough, and you are correct here.

Now force your particle into an up state:  you therefore know mine is down, and I can measure it.

This is very much wrong. Entanglement does not mean that 'what is done to one particle affects the other'. Yes, a message could be sent if that were true, but it isn't. Spooky action at a distance (as it is called) has never been demonstrated. If it was, all the local interpretations that forbid it would have been falsified.

Spin entanglement says (in short) that if you measure both things in the same way, the results will be correlated.  If you force one of the particle spins, that is the same as declining to take one of the two measurements, leaving nothing to compare.

[paul cotter]

Thank you, Halc. I had always assumed, mistakenly, that "spooky action at a distance" was a real phenomenon. This is a problem that arises when one has not had proper tuition in a subject-it's 50 years since I attended college and the only quantum theory covered was in connection with semiconductors, apart from the basic stuff ie failure of classical theory to deal with black body, photoelectric and orbitals.

[Petrochemicals]

Jim

If you have 2 particles and you give one to your accomplice to go on their light speed ship,

It is not possible for a ship to go light speed but we can assume it is possible.  Let's call this accomplice Jim.
 

if they conveyed information to you from 1LY, it would only be at the speed of light, you could have garnered the information yourself if you went on their ship at the speed of light.

Ok so Jim who is one ly away sends a signal, I can:
1.  Wait a year for the signal.
2.  Fly to the Jim at light speed and ask what was in the signal, which would take a year.
3.  Fly in my ship towards Jim at light speed and intercept the signal in 6 months.

Where do the entangled particles come in?

If precisely 1 year after your accomplice departed, another conspiritor from 1LY the opposite direction to that of your accomplice arrives bringing an entangled particle,

Let's call the new conspirator Bob.
So when Jim is one light year away, Bob shows up having flown one ly from the opposite direction.  He has an entangled particle.  I have no idea what this new entangled particle has to do with anything.

you and likewise your explorer accompice would know what was going on in either direction

Who is the explorer accomplice (Jim I assume)?  What is it that we would know 'is going on'?

but you would know the information if you had travelled to the lication and so could your accomplice.

What information?  The signal?  So after 1 year both Bob and I would know the contents of the signal sent by Jim.  That is correct if that is what you are saying. 
I don't see how this has anything to do with entanglement.

It was written in context to the op considering the instantaneous transmission of information utilising the quantum entanglement of particles. The gist being you would need to transport the particle, light speed or any other. Any information that is aquirable at the speed of light is OK, but if particles could be read it would lead to a situation where you can infact get information faster than light.

[paul cotter]

Even if one could dictate the state of a remote entangled particle by manipulating the local one, which cannot be done, one still would have to transport one of the entangled pair to the remote location: it would be simpler to just transport the relevant information that's required.

[Origin]

but if particles could be read it would lead to a situation where you can infact get information faster than light.

Got ya. If information could be transferred by entangled particle pairs you could send information faster than light, in fact it just might be instantaneous.  But you can't transfer information by entangled particle pairs so... it's all academic.

[Petrochemicals]

could

That is what they said about the alchemists too!

Even if one could dictate the state of a remote entangled particle by manipulating the local one, which cannot be done, one still would have to transport one of the entangled pair to the remote location: it would be simpler to just transport the relevant information that's required.

I wonder what relitavistic effects have on quantum entanglement.

[Kryptid]

It is impossible, but so was the splitting of the atom, flight, etc.

The difference is that there are no laws of physics preventing nuclear fission or flight.

[alancalverd]

Laws of physics neither permit nor prevent: they describe.

[Kryptid]

What they describe prevents us from making things like perpetual motion machines.

[alancalverd]

Or explains why they don't work. We observe conservation of energy and momentum, and increasing entropy, all of which conspire against an "overunity" or even a "unity" machine.

Problem is that if we apply said laws retrospectively, we can't explain the status quo because they give us a date for a Big Bang but don't tell us what happened beforehand.