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Can Quantum Entanglement Make Faster- Than- Light Communication Possible?

 
 
Reply Tue 16 Aug, 2016 09:36 pm
If I had a little box full of particles and you had another box full of particles that were entangled with the particles in my box and we were separated by twenty light years. If I alter my particles in some way would you be able to detect this at your end? I mean if the box had the correct sensors to detect the altered particles.
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Type: Question • Score: 1 • Views: 1,972 • Replies: 23
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rosborne979
 
  1  
Reply Wed 17 Aug, 2016 04:29 am
@TomTomBinks,
I've read several articles over the years which answer that question. I even listened to 45 minute podcast discussion on the subject. They all say that causality (and light speed limits) are not violated. Unfortunately, no matter how hard I try, I can't understand the explanation.
0 Replies
 
maxdancona
 
  1  
Reply Wed 17 Aug, 2016 07:52 am
@TomTomBinks,
Let's do a little thought experiment in the form of a game. Let's turn particles into coins that have this "magical" property (and only this one magical property).

The coins are paired... and if you flip one coin in a pair randomly, the other one will instantly change to the opposite side. So if one coin is flipped and comes up heads, the other coin in the pair will instantly turn itself into tails (and vise versa).

Here is the catch... the "magic" in the coins only works when you flip one of them randomly. Reaching down and turning over the coin doesn't work (if you try this the other coin in the pair will be unaffected).

Except for this one bit of "magic" the coins work just like normal coins in every other way.

Do these rules make sense?

maxdancona
 
  1  
Reply Wed 17 Aug, 2016 07:53 am
@maxdancona,
If you understand this how this "magic" works... and the one rule behind it, the question is how would you use this strange property of these paired coins as a long distance communication device?

0 Replies
 
parados
 
  1  
Reply Wed 17 Aug, 2016 08:23 am
@maxdancona,
Can you control when you make the random flips, which coins you are flipping and can you tell what the result is after you flip it?

If the answer to all of those is true then it would be possible to have a group of paired particles that could result in communication. That assumes that the coins can't just randomly flip themselves for whatever reason.

The real question is how do you get the paired particles to be at each end of the communication channel. You have to find the paired particles, then you have to transport them in some fashion or communicate that they are pairs. Then you need to isolate a group of those pairs to use for communication. All of this assumes there are only pairs and not triplets, quads or any other group that will all act together which would add interference that would negate almost all attempts.
maxdancona
 
  1  
Reply Wed 17 Aug, 2016 08:28 am
@parados,
Maybe my metaphor isn't the best Wink I will have to work on it. You are right that if you can tell which coins are changing you can use that to transmit information. This is not possible in real life.

In real life, we have ways to get paired particles, but it is impossible to tell which particles are being measured without measuring them.
0 Replies
 
giujohn
 
  1  
Reply Wed 17 Aug, 2016 12:51 pm
@TomTomBinks,
The simple answer is although it appears that the change from one particle to another is faster than the speed of light it does not violate the speed of light "speed limit" because no information was exchanged.
TomTomBinks
 
  1  
Reply Wed 17 Aug, 2016 10:36 pm
@giujohn,
After reading more on this topic, I seem to understand it less than before I started. Thank you all for trying.
giujohn
 
  1  
Reply Thu 18 Aug, 2016 05:05 am
@TomTomBinks,
"If you are not completely confused by quantum mechanics, you do not understand it." John Wheeler

The problem is quantum mechanics is not intuitive. It's hard for us to wrap our head around quantum mechanics because we live in the macro or classical physics world and cannot directly
interact with the Quantum relm. But experimentation that can be repeated with the same results is proof enough for me to accept the tenants of quantum mechanics
0 Replies
 
fresco
 
  1  
Reply Thu 18 Aug, 2016 09:52 am
@TomTomBinks,
Don't think about two separate particles separated by what we call 'space'. Think of a single quantum system whose 'state' is affected by the actions of a particular observer. That is why the second observer cannot 'receive' information about the state changes observed/effected by first observer since the second observer would instigate his own observation event. ( Its like going to the bathroom....nobody can go for you !).
TomTomBinks
 
  1  
Reply Thu 18 Aug, 2016 09:48 pm
@fresco,
OK, let me try again to get this. This is what I think I know: Two particles are "entangled". Meaning they are somehow linked to one another. Their qualities compliment one another as in if one is "spin up" the other will be "spin down". When a particle is measured, it changes the quality of the particle and ends the entanglement.
So Observer A measures the spin of a particle, then observer B measures the spin of it's entangled mate, they will always observe opposite qualities. After the observation is made, the entanglement ceases.
OK, if that's right then I see how it can't be used for communication.
Also, what's the mystery? Some mechanism always generates these particles in pairs with opposite qualities. If you measure one "spin up", of course the other will be "spin down"
I know I'm still missing something...
fresco
 
  1  
Reply Fri 19 Aug, 2016 01:20 am
@TomTomBinks,
I suggest that you are missing the fact that following Einstein 'simultaneity' cannot be established for the 'event' measured by the separate observers. Any 'time' measurements are subject to the speed of light which deflates a 'communication faster than light' thesis.
maxdancona
 
  1  
Reply Fri 19 Aug, 2016 06:04 am
@fresco,
Quote:
I suggest that you are missing the fact that following Einstein 'simultaneity' cannot be established for the 'event' measured by the separate observers. Any 'time' measurements are subject to the speed of light which deflates a 'communication faster than light' thesis.


This is nonsense.

The speed of light is a constant. How are time measurements "subject" to a constant?

And what does it mean to "deflate" a thesis? I could easily design an experiment to test a claim of faster than light communication.


fresco
 
  1  
Reply Fri 19 Aug, 2016 09:31 am
@maxdancona,
Wrong. Read Einstein on relativity. The speed of light is constant FOR ANY OBSERVER . That is why 'simultaneity' cannot be established for the observation 'events' of the 'two' particles as far as the separate observers are concerned. 'Events' are relative to observer-observed interaction.
[Deflate means 'to remove the foundational axioms of a concept. For example, in psychology some authors deflate the concept 'mind' as merely an epiphenomenon of 'cognitive processes'. In this instance 'faster than light' is deflated by the conflict between separate observers in space time versus the non locality of a quantum event. The conflict is as epiphenomon of the coextension of observer and event]
As far as your hypothetical experiment is concerned', are you not forgetting that all 'observation' is limited by the speed of photons ? The philosophical issue identified by Kant and re-interpreted by Heisenberg is that 'we never experience nature directly, but only the effects of our interaction with it'. In short 'phenomena' do not reside 'out there' even though we can play the game of assuming they are at non quantum levels.
maxdancona
 
  1  
Reply Fri 19 Aug, 2016 09:48 am
@fresco,
I have read Einstein on relativity... while I was getting a Physics degree. I am telling you that from the point of view of someone who understands physics, you aren't making sense.

Yes, it is true that the speed of light is constant for any observer (whether you capitalize it or not). To understand this, you need to understand the concept of frames of reference. That doesn't mean that you couldn't set up an experiment to show faster than light communication of information (if such a thing were possible). This is what you seem to be saying.

We recently showed that quantum entanglement happens at a rate faster than the speed of light. If someone showed that information could be exchanged over the same sort of experimental setup... would that (using your funny terminology) "inflate the thesis".
fresco
 
  1  
Reply Fri 19 Aug, 2016 09:57 am
@maxdancona,
'Information' is another related philosophical quagmire The Uncertainty Principle should give you a hint.
maxdancona
 
  1  
Reply Fri 19 Aug, 2016 10:11 am
@fresco,
The Uncertainty Principle is a mathematical result of Schrodinger's equation. It has been tested by experiment. This has nothing to do with a "philosophical quagmire".

If you are talking about philosophy, then talk about philosophy. Just stop pretending that it has anything to do with actual, testable science.

Your mistake is that you are using some understanding of "philosophy" to inform your ideas about science. I am trained in science (not philosophy). It may be that your posts make perfect sense as part of a philosophical construct... I couldn't tell.

But from the perspective of science, you aren't making any sense. In philosophy you can just make stuff up that seems right. Science doesn't work like that.


fresco
 
  1  
Reply Fri 19 Aug, 2016 12:03 pm
@maxdancona,
Quote:
I am trained in science (not philosophy)

Laughing
...and I am trained in both !
The issue here is not to regurgitate our lecture notes, but to try to get a handle on the non-intuitive nature of quantum events. It is therefore both scientifically and philosophically respectable to identify the co-extension of 'observer' with 'the observed' (the antithesis of 'naive realism') as a significant issue and to use it to highlight that words like 'event', 'information' and 'locality' become detached from normal usage at the quantum level. You speak of 'mathematics' and 'testing' as though those words could be independent of the consensual (paradigmatic} human investigative operations being utilized. This is the very crux of celebrated statements like 'nobody understands quantum theory' (e.g. Feynman). The word up for grabs here is indeed 'understanding', and that is where reference to mathematical models becomes nebulous irrespective of the functional 'success' of such models in human attempts to predict and control what evolves as what we conceive to be 'the world'. Indeed the discussion of term 'scientific realism' has generated copious subsections on the shelves devoted to ontology and epistemology which tend to more extensive than those devoted to theoretical physics. I doubt whether the peer reviewed authors of such texts would agree they were 'making stuff up' , despite Einstein's high valuation of 'imagination'.

maxdancona
 
  1  
Reply Fri 19 Aug, 2016 12:11 pm
@fresco,
Fresco,

There are at least two points you have made that indicate to me that you don't know what you are talking about when it comes to real science.

I am curious what your training in science is... Quantum Physics involves the solution of mathematical equations using differential calculus, have you taken a real Quantum course that involves solving Schrodinger's equation using differential calculus?

If you have, then we could have a discussion where you explain to me how your claims have anything to do with actual Quantum Physics.

Because up to this point, several things you have said make no sense.
fresco
 
  1  
Reply Fri 19 Aug, 2016 01:53 pm
@maxdancona,
I'm not going to wallow in my qualifications, other than to say I have published work in experimental phonetics which included the use of Fourier Transforms in speech spectography and the study of Signal Detection Theory. As you will know the Uncertainty Principle also operates in waveforms by trading frequency with amplitude information, so 'information' becomes a focal issue in two respects, 1. in the physical analysis of the acoustic signal per se and 2. with respect to paralinguistic aspects of communication which contribute to expectancy. Indeed the latter is a major contributor since the waveform can be severely distorted yet remains intelligible.
The study of speech perception obviously pays heed to the study of perception in general, in which both information theoretic and non informational models have been proposed, the former being spectacularly unsuccessful in attempts at computer modelling of cognitive processes.
So allow me to suggest that on the topic of 'information transmission' which is what this thread is about, the one who needs to do a bit more reading is you since you don't appear to understand the epistemological problems associated with it, especially those concerned with the status of modelling.
 

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