Author Topic: Almost an ansible? entanglement without classical particles or EM Comms  (Read 24086 times)

Offline Stormbringer

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EDIT: Unless i am mistaken any relativistic travel allows time travel and we have observed physical objects with mass that are traveling at relativistic speed with our astronomical instruments. Certain celestial objects that got booted by a massive gravitational partner at some point. If one of these objects were to return to it's starting point at speed it would amount to time travel.

No, it wouldn't amount to time travel.  You seem to misunderstand the word "relativitstic" or its implications.  Going faster than light would amount to time travel.  The word "relativistic" means, roughly, "close to but less than the speed of light".
No- i know well what these terms mean. And merely relativistic travel is also time travel due to gamma factor. if i go to a distant star at 99.99 percent C i travel in time. I experience an abbreviated time compared to observers at home. in my perspective the trip takes mere moments or weeks at worst. That is time travel. It's not your definition of time travel; but it is time travel.

If i return home at 99.99 percent light speed; I will have aged moments or weeks at worst while everyone I greet at journey's end will be about 9 or ten years older. I will have effectively traveled to the future skipping all the inconvenient things in between moments.

OK, then you're just making up your own definition for a term that already has a very widely understood meaning.  What's the point of that other than deliberate miscommunication?
No. I am not making up a new definition of time travel. Other people, some of them physicists have called the scenario I described time travel. It's in the popular literature.
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Offline Stormbringer

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no the light cones -the time lines diverge. If i am in the crew of that ship my time is abbreviated (radically) compared to stationary observers back home. and as I said I am not alone in calling this situation time travel.
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Offline Bob Shaw

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Even time travel where you could not effect your own timeline would be very very useful for information gathering and for stealing acquiring artifacts (to preserve them for posterity) and grabbing specimens say for botany, biology or zoology. if there are  "many worlds" then some would be so close to identical that the only difference could be some detail so minor as to be unnoticeable.

Tell that to the dinosaurs who invented the Iridium Bomb.

Offline Patchouli

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I hope one day we will find a way to send information faster then c as the speed of light lag is an inconvenience even within the confines of the solar system.
Though the existence of some sorta FTL com may explain the Fermi paradox with SETI as maybe civilizations only use radio or laser communications for a short period before moving to something else.
« Last Edit: 04/19/2015 01:21 AM by Patchouli »

Offline blast335

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I had this idea too, so how it work's in my mind is that they have 2 entangled sets, one for receiving and one for sending, they would come up with a code, like Morse code, and send photons into their sending particle, then on the other side, the entangled particle would emit a photon and that photon would activate a detector, then a computer attached to that detector would decode the message. Assuming I under stand all of the details.

Offline JasonAW3

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I've always wondered if Quantum Tunneling, outside of a gravity well, could effectively produce simultanious communication over interstellar distances.
My God!  It's full of universes!

Offline SteveD

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I have the strangest hunch that everyone here is wrong.  You can send a message back in time with a quantum effect, but that message cannot be distinguished from noise (decoded or decrypted) until such a time that it would not violate causality.  For example: entangle a photon.  Travel one light year distant.  You send a message.  Your recipient gets it now.  The recipient then sends back a reply that goes on "the stack" a year in the past.  You cannot distinguish the contents of the message you received a year ago, or even that a message has been sent, until now (or most likely a couple of weeks from now when whatever decryption equipment you have finishes processing the signal).  Because distances on one planet are short, it is quicker to receive a cheat sheet via EM broadcast than do the decryption.

Offline Stormbringer

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not ansible related but topical:

http://phys.org/news/2015-08-physicist-unveils-entangling-massive.html

its a proposal to demonstrate quantum entanglement of 100 gram masses; the largest massive objects so far tried.
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Offline ChrisWilson68

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I had this idea too, so how it work's in my mind is that they have 2 entangled sets, one for receiving and one for sending, they would come up with a code, like Morse code, and send photons into their sending particle, then on the other side, the entangled particle would emit a photon and that photon would activate a detector, then a computer attached to that detector would decode the message. Assuming I under stand all of the details.

How many times does this same myth have to be busted?  Entanglement does not give faster than light communication.

This is a well-known result in physics.

Base your fantasies of faster-than-light communication on something else.  Entanglement won't do it for you.

Offline ChrisWilson68

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I've always wondered if Quantum Tunneling, outside of a gravity well, could effectively produce simultanious communication over interstellar distances.

Nope.

Quantum tunneling is a well-understood part of quantum physics.  The rules under which it happens have been proven mathematically to never transmit information faster than light.

You really do need new physics to get faster-than-light communication.  There's no point in trying to use phenomena that are described already by known physics.

Offline blast335

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I had this idea too, so how it work's in my mind is that they have 2 entangled sets, one for receiving and one for sending, they would come up with a code, like Morse code, and send photons into their sending particle, then on the other side, the entangled particle would emit a photon and that photon would activate a detector, then a computer attached to that detector would decode the message. Assuming I under stand all of the details.

How many times does this same myth have to be busted?  Entanglement does not give faster than light communication.

This is a well-known result in physics.

Base your fantasies of faster-than-light communication on something else.  Entanglement won't do it for you.
Well we can teleport quantum states through entangled particles, so why can't we devise a system to interpret these teleported states into messages?

Offline QuantumG

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Well we can teleport quantum states through entangled particles, so why can't we devise a system to interpret these teleported states into messages?

What do you think they're called quantum states and not quantum messages?

Jeff Bezos has billions to spend on rockets and can go at whatever pace he likes! Wow! What pace is he going at? Well... have you heard of Zeno's paradox?

Offline ChrisWilson68

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I had this idea too, so how it work's in my mind is that they have 2 entangled sets, one for receiving and one for sending, they would come up with a code, like Morse code, and send photons into their sending particle, then on the other side, the entangled particle would emit a photon and that photon would activate a detector, then a computer attached to that detector would decode the message. Assuming I under stand all of the details.

How many times does this same myth have to be busted?  Entanglement does not give faster than light communication.

This is a well-known result in physics.

Base your fantasies of faster-than-light communication on something else.  Entanglement won't do it for you.
Well we can teleport quantum states through entangled particles, so why can't we devise a system to interpret these teleported states into messages?

There's a theorem in quantum physics called the "No Communication Theorem".  It says that you can't use entanglement for communication.  The theorem has been mathematically proven from the rules of quantum physics.

https://en.wikipedia.org/wiki/No-communication_theorem

Offline Stormbringer

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Offline ChrisWilson68

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a (2 Bit) ansible!

http://news.sciencemag.org/physics/2015/12/physicists-figure-out-how-retrieve-information-black-hole

No, not at all.  The article has nothing to do with faster-than-light communication.  It's about using entanglement (which is known not to enable faster-than-light communication) and how it relates to information not being lost in a black hole.

Offline 1

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Explain quantum tunneling then.

     A particle going from point A to point B without transitioning through the interveining space certainly seems to violate the concept of information traveling faster than light.

     Admittedly this, so far, has only been observed on the nanoscopic scale, but the transition certainly SEEMS to be happining at faster than light velocities.
I sure can't explain quantum tunnelling :)

..but the physicists who claim to understand it say that the mathematics that predict quantum tunnelling also explain why it cannot be used to transfer information faster than light.


I can. The issue with tunneling isn't that a particle travels from region A to region B in zero time (the word 'point' has subtle connotations and should not be used), it's that said particle appears to traverse a region that's classically disallowed.

This is a consequence of the QM hamiltonian equation requiring fields 'n' wave solutions. In the classical world, having a particle bounce off a wall (an effective reflection coefficient of 1) is a perfectly acceptable boundary condition; and a particle measured in region A will forever be bound to region A. When dealing with fields and waves, the only time this is mathematically possible is when you have a barrier of infinite potential energy; and barriers of infinite potential energy simply haven't been found nor are likely to be found anywhere in nature. Consequently, a quantum field (read: the particles' wavefunction) requires solutions to maintain smooth-'n'-continuous boundary conditions similar to those required by just about every other known field. This requires a non-zero permeation into an otherwise forbidden zone, and is analogous to evanescent solutions found in classical E&M. These solutions decay very, very, very rapidly, but never actually reach zero magnitude. Your reflection coefficient is always less than 1. Thus, at the end of the forbidden zone, region B, a small but nonzero part of the wavefunction couples back into an allowed state. This allows a particle once found in region A to appear in region B.

The direct answer to your question about tunneling, however, is this. There is still a very lively ongoing debate about proper interpretation of what it means to both collapse and re-expand the wavefunction, but the long and the short of it is that a wavefuction, once collapsed (read: a particles position is first measured) then needs time to re-expand and permeate that forbidden region. Subsequent measurements on that particle, if done before the wavefunction has time to re-expand, will always measure the particle in region A. Only after a sufficient length of time has passed, which is greater than the amount of time it would take light to travel from region A to B, could the particle then be found to have tunneled into the other region. The speed limit of C is not an explicit requirement of quantum mechanics as I understand it, but it is a requirement that appears to be obeyed in experiment.

Offline Stormbringer

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