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Offline yor_on

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Is remote entanglement not proven ?
« Reply #25 on: 19/04/2011 19:12:57 »
That one I loved JP "he's just against the fact that it's played up as something very bizarre, since the only reason it seems bizarre is if you try to understand it in terms of classical mechanics.  If you realize they're obeying the rules of quantum mechanics, it's perfectly natural."

Heh :)

And sane too, I suppose? :)

No, only joking a little JP. I agree wholeheartedly to that view, but from my own limited understanding, however pitiful that might be:) To me both relativity and QM question our concepts of time and distance, but nobody seems to react to it?

It seems quite clear to me that if two so different views of the universe both find a common point of view in that, then that has to be a cornerstone for 'merging' the ideas into one. And as they both, to me, makes a very good sense, although describing 'SpaceTime' differently, I do want them to merge, and that's where the ideas of loops comes in. I'm not sure I need to see those as having a 'size'.

Size is a relative concept it seems, and also a description only getting its attributes under a 'arrow of time'. But this isn't what we discuss I guess :) So, collect that one too sciconoclast  :) Jp:s description I mean, it's a nice quote to use.

Why I'm finding it hard to see the difference in 'remote/far' and 'near/local' is because a entanglement, to my eyes, doesn't use our concepts of distance, and time. So using definitions that won't make sense for it loses me. But now I see where you got it from, and thanks for the lecture :) eh, both of you. That's what nice with this site, we don't only present 'sensationalism', but also links to 'gold corns' of contemporary science. It will be fun listening.
« Last Edit: 19/04/2011 19:15:51 by yor_on »
 

Offline JP

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Is remote entanglement not proven ?
« Reply #26 on: 19/04/2011 19:31:49 »
No, only joking a little JP. I agree wholeheartedly to that view, but from my own limited understanding, however pitiful that might be:) To me both relativity and QM question our concepts of time and distance, but nobody seems to react to it?

To me his point is (and it's a very good point that not enough people appreciate) that the there is no reason for classical concepts to be useful in explaining quantum concepts.  And similarly, there's no reason for Galilean/Newtonian concepts to be useful for describing relativistic concepts.

It goes the other way around.  Quantum mechanics should explain how classical concepts arise and relativistic concepts should explain how Galilean/Newtonian concepts arise. 

By the way, I was happy to see that Coleman sites my favorite Feynman video on magnetism as an example of why these kinds of explanations only go from "deeper" to "less deep" theories:

Quote
Why I'm finding it hard to see the difference in 'remote/far' and 'near/local' is because a entanglement, to my eyes, doesn't use our concepts of distance, and time.
The only interesting point, I think, is that "remote" entanglement seems more magical (counterintuitive to our classical sensibilities) than nearby entanglement.  They're both the same thing from the quantum viewpoint.
 

Offline sciconoclast

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Is remote entanglement not proven ?
« Reply #27 on: 19/04/2011 23:53:36 »
Hi JP

I do not think you were paying very much attention to the Coleman lecture.  You got it backwards.  He is saying that those who think there is an entanglement are thinking in classical terms and in quantum terms there is no entanglement.

The main point of the lecture is that there is no entanglement. 

Thanks for the link correction.  I changed it in the previous post.  
« Last Edit: 20/04/2011 00:13:51 by sciconoclast »
 

Offline JP

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Is remote entanglement not proven ?
« Reply #28 on: 20/04/2011 01:12:17 »
Hi JP

I do not think you were paying very much attention to the Coleman lecture.  You got it backwards.  He is saying that those who think there is an entanglement are thinking in classical terms and in quantum terms there is no entanglement.

The main point of the lecture is that there is no entanglement. 

If he says that in those words (and I can't find it), then it's a matter of semantics.  He goes through a long derivation around the 30 minute point that agrees with what most physicists mean when they say entanglement. 

Can you point me to the time in the lecture where he says that there is no entanglement, using the word entanglement itself? 
 

Offline sciconoclast

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Is remote entanglement not proven ?
« Reply #29 on: 21/04/2011 04:07:28 »
Coleman does not use the word entanglement.  However, "linked", which he does use means the same thing.

At 23minutes in the speech he says " Experiments done at space like separations cannot interfere with each other.".   This is physics speak for no entanglement.

At 46minutes in the speech he says " I will argue that it is a fact that there is no special measuring process, no reduction of the wave function in quantum mechanics, no indeterminacy, and nothing probablistic; only deterministic evolution.".   Again physics speech for no entanglement.

And then he sums it up at 1 hour and 2 minutes by asking if the results look like " all that ever happens is causal evolution of quantum mechanics.".

To anybody that can follow this lecture it is clear that there is no entanglement.   I know, JP, that you are capable of understanding it but suspect that you only skimmed it for key words.     
 

Offline JP

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Is remote entanglement not proven ?
« Reply #30 on: 21/04/2011 04:45:25 »
First you tell me I'm not paying attention to his lecture and that the main point is that there is no entanglement.

Then you admit he never says there is no entanglement, but that "to anybody that can follow this lecture it is clear that there is no entanglement."

I'm going to have to disagree with you on that one.  For starters, Coleman was a very smart guy, and if he wanted to argue against entanglement he would use the word.  He chose his language very carefully to argue against the misconception that the results of measuring entangled states are caused by some action-at-a-distance.   

Second, the case he uses as an example is the GHZ state, which was chosen precisely because it shows how entanglement, which is a purely quantum phenomenon, can't be explained by classical reasoning.

Third, I can follow his lecture, and I know the details of the quantum mechanics he's describing.  I can verify that he isn't arguing against entanglement, no matter how much you'd like to tell me otherwise.  Entanglement is actually a purely quantum phenomenon that proves his point.  Perhaps you're confusing entanglement with action-at-a-distance?  I certainly agree with you and he that there isn't some faster-than-light communication happening between distant particles.
 

Offline Geezer

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Is remote entanglement not proven ?
« Reply #31 on: 21/04/2011 05:55:13 »
In Scotland, if you happen to "do in" your mother-in-law, but the jury does not think the prosecution did a very good job, they might return a verdict of "not proven". In that event, the jury concluded that you damn well did it, but they would have liked a little more substantial evidence.

http://en.wikipedia.org/wiki/Not_proven

In science, it's always easy to apply a not proven verdict. The hard thing is to prove a credible alternative.
 

Offline CPT ArkAngel

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« Reply #32 on: 21/04/2011 07:42:43 »
At the beginning, after his introduction, he clearly said that there is no non-locality in QM, he then said that physicists perpetuating this idea are wrong. He never spoke about entanglement, only about the certainty of uncertainty... [:o)]

People, in the audience, should have asked him how he explains the double slits experiment.
« Last Edit: 21/04/2011 08:41:15 by CPT ArkAngel »
 

Offline JP

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Is remote entanglement not proven ?
« Reply #33 on: 21/04/2011 13:37:17 »
People, in the audience, should have asked him how he explains the double slits experiment.

I'm not sure he'd have a problem with it.  Each slit acts locally on the wave function, and the interference pattern is a local effect resulting from causal evolution of the wave function.  That's exactly what he was stressing is the explanation for quantum effects.
 

Offline sciconoclast

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Is remote entanglement not proven ?
« Reply #34 on: 21/04/2011 15:43:32 »
JP
   You stated that Coleman argued against "the misconception that the results of measuring entangled states are caused by some action-at-a distance" and in my case "Perhaps you're confusing entanglement with action-at-a-distance.".

Didn't Einstein refer to Bohr's "remote entanglement" as "spukhafte fernwikung" ( spooky action at a distance).

CPTArkAngle
    Good to see some additional participants.   You mentioned that Coleman "clearly stated that there is no non-locality"   Isn't the instantaneous collapse of the common non-locality for the entangled particles the basis for Bohr's concept of remote entanglement.

If I have time I will see if I can find the Coleman lecture on double slits and provide a link.

Geezer
     In an earlier thread I tried unsuccessfully to explain to you what I meant by the the difference between quantum mechanics and quantum theory ( meaning the Copenhagen interpretation ).  The two views presented in the lecture illustrate what I was poorly trying to convey. 

In general
Those who failed to accept Bohr's interpretations ( sometimes referred to as voodoo physics ) where often referred to by Bohr's supporters as classical die-hards.   Coleman's reversal of the labels was part of his humor.  The lecture is full of this type of supple humor.  It is very funny as well as informative.   The lecture is not specifically about remote entanglement but all of the weird portions of the Copenhagen  interpretation.  Hence, the bit about the robot not being able to deliver results to Sidney to expose how "silly" the conscious observation requirement was.       
« Last Edit: 21/04/2011 15:45:20 by sciconoclast »
 

Offline yor_on

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« Reply #35 on: 21/04/2011 16:13:24 »
From a philosophical standpoint it's not silly at all sciconoclast. There you have to start with what 'observe' and define your proposition from that. Any other way of treating it is 'unfinished'. When you are dead it won't matter to you if the universe continue or not. To you it will be the same, as long as you don't expect life after death.

So without the observer there can be nothing observed. That actually gives a lot of weight to the Copenhagen definitions idea of wave functions collapse being directly coupled to the observer. Myself I've redefined that aspect slightly to include 'everything interacting', allowing all objects a property of 'existing' on their own. that way I sneak around that corner stone of absolute truth, although not really :) As in the end, from our point of view, it doesn't matter how many trees that fall in that Forrest as long as we're not there experiencing it. This kind of logic will be needed for any true TOE, any other type of definition will be incomplete.
 

Offline JP

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« Reply #36 on: 21/04/2011 16:18:39 »
JP
   You stated that Coleman argued against "the misconception that the results of measuring entangled states are caused by some action-at-a distance" and in my case "Perhaps you're confusing entanglement with action-at-a-distance.".

Didn't Einstein refer to Bohr's "remote entanglement" as "spukhafte fernwikung" ( spooky action at a distance).

Einstein did refer to entanglement as "spooky action at a distance," but he was trying to explain the absurdity of entanglement by appealing to the kind of mistaken logic that Coleman is arguing against: namely that there is some kind of faster-than-light interaction between distant entangled particles.  More importantly, as far as we can tell now, Einstein was wrong on this one.  At any rate entanglement is not synonymous with action-at-a-distance.

Coleman would probably also argue that "remote entanglement" is a misnomer, since there is nothing special about separating entangled particles.  Proper preparation of the initial state + causal propagation of the particles under the rules of quantum mechanics explains everything.

By the way, to make sure we're on the same page, when you say "entanglement," what do you mean?
 

Offline yor_on

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« Reply #37 on: 21/04/2011 16:54:06 »
Yes, 'spooky action at a distance' builds on the concepts of objects being a singular corpuscle existing on their own interacting with something else faster than the speed of light in a vacuum. On the other hand, modern terminology also differs between 'information' and 'non-information'. The entanglement as such contain no meaningful information and therefore you might define it as there is no 'action' taken on that remote twin, until you actually gone there to 'observe' it. And to do that you will have to obey light speed.

This is the premise that 'allow' entanglements as I understands it. That you under no circumstances will be able to use it for transferring meaningful information. If you could break that barrier physics would change and FTL would be true.
 

Offline sciconoclast

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« Reply #38 on: 21/04/2011 23:36:36 »
JP: defining terms is a good idea.

How do I define entanglement?  Actually the thread is about remote entanglement.   Some events can create correlated particles and this could involve a short lived initiating process that could be called entanglement; but this is not what I am talking about.  I think of the Bohr remote entanglement as an abstract set of interdependent probabilities, or non-locality, in which none of the particle parameters are realized until one of the particles is actually tested for, resulting in the simultaneous realization of both particles with correlated parameters and the collapse of the non-locality, or quantum wave function.

Here are some on-line encyclopedia definitions which I think are similar. 

from http://www.daviddarling.info/encyclopedia/Q/quantum_entanglement.html
"An instantaneous link between particles that remains strong, secure, and undiluted no matter how far apart the particles may be."......"Its fundamentally nonlocal.  A measurement of particle A affects its entangled partner B instantaneously, whatever the separation of distance."

from en.wikipedia.org/wiki/quantum_entanglement
"Quantum entanglement is a property of the state of a quantum mechanical system containing two or more degrees of freedom, whereas the degrees of freedom that make up the system are linked in such a way that the quantum state of any of them cannot be adequately described independent of the others even if the individual degrees of freedom belong to different objects and are spatially separated."

Notice the use of the word linked in both of these definitions which is also the term used in the Coleman lecture.
 

Offline JP

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« Reply #39 on: 22/04/2011 00:32:59 »
I think the confusion in those definitions is between what is measured in experiments versus the interpretation of what is happening, so let's step back to that. 

Experimentally, people have generated "entangled" photons and found that when measured, they generate statistics that are not possible with any classical theory.  Now, what I said in my post way back at the beginning of this thread is that these experiments aren't 100% conclusive, but they seem to be very good.  However, you can deny that entanglement exists by claiming that these experiments are wrong and that there is some underlying classical-like theory wherein the measurements are determined by internal hidden variables within each particle.  This is why I said initially that entanglement wasn't proven.

But what we seem to be debating now is what happens if these experimental results are correct, and that "entangled" particles are generating measurements that cannot be explained classically.  If that's the case, then you've already assumed that the experiments are true.  The results of those experiments are that the two entangled particles lead to measurement results that show quantum statistical correlation between them, even though they're separated.  This is the "linking" that Wikipedia is talking about.  That's as far as I'm going in defining entanglement. 

Now, you have a bit of freedom in interpreting what this means is physically going on, so long as your interpretation doesn't disagree with the experimental results.  The first definition you give from "the internet encyclopedia of science" seems to be suggesting that it's "an instantaneous link between particles that remains strong, secure, and undiluted no matter how far apart the particles may be", i.e. that it's an active link between particles--they send something to each other and that something is what keeps the measurements correlated.   

Now back to what Coleman is saying---he thinks the experimental results are good.  In other words, he thinks that quantum mechanical "entanglement" is a real thing and you generate statistics that don't have a classical, hidden-variables cause.  He says so much around the 30 minute point when he goes though the example of the entangled GHZ state.  However, he disagrees with thinking this is caused by an "active link," so he disagrees with the first definition you posted. 
 

Offline yor_on

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Is remote entanglement not proven ?
« Reply #40 on: 22/04/2011 07:16:02 »
Yes, entanglements is one thing only. Something that can be seen as 'one particle' although as no 'particle' we ever seen. It's a particle whose constituents are smeared out in the universe, but compared to the idea of a wave 'smeared out' where we say it is nowhere and everywhere, this entanglement keeps its 'boundary's'. Think of space and distance as something it just wraps up. The entanglement just crumples space-time up and 'spits itself out' :) In our measurement. It states that our ideas of distance are wrong, very loud and clear.

And I don't care how you 'split' it. To me both QM and Relativity states the same. We are fooled by 'time' and we are fooled by 'distance'. And the 'foolery' builds on our own 'personal time' never varying as measured inside our own 'frame of reference'. What that do is to make it extremely hard to find any difference except when comparing those 'frames of reference'. And what that states to me, is that we all see a different 'SpaceTime'. In a way we all become the 'center' of the universe from where all other definitions of time and distance are created.

A very weird idea. To make it work we need to find what makes our impression of a whole and 'unbroken' SpaceTime possible, and that is radiation. That constant is what gives us a 'whole' universe. And that constant also tells us, in the way it blue and red shift (Doppler), that 'distance' is something else than what we think. And the same does a Lorentz contraction, which as I see it is real, the universe will 'contract' in the motion of the traveler.

So which one of those two is more real? Time dilation or Lorentz contraction?

That depends on your definitions. Mine is that time is more of a 'constant' than Lorentz contraction, in that 'times arrow' always will give you the same chunks of time when measured inside your frame, and that in fact is the only place from where you can measure it. All other information you will get is second hand, not fitting without a translation. Even if not informed of the existence of 'frames of reference' you would still have no trouble defining our universe. And it would take a twin experiment for you to realize that there was something strange going on.

So?
« Last Edit: 22/04/2011 07:17:36 by yor_on »
 

Offline Geezer

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Is remote entanglement not proven ?
« Reply #41 on: 22/04/2011 07:49:20 »
It has been demonstrated repeatedly that time is a purely local phenomenon.

Why would we be surprised to learn that particles that travel rather quickly (from our perspective) don't pay any attention to our idea of time?

(I'm heading for my underground bunker now.) 
 

Offline CPT ArkAngel

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« Reply #42 on: 22/04/2011 08:06:51 »
So which one of those two is more real? Time dilation or Lorentz contraction?

I am wondering about that for more that 2 months now... One thing is sure, it is that you cannot have both in the same equation. Probably, the answer is that space and time are indivisible...

Could light be spacetime? Space=photons, spacetime=massive particles (made of curved photons)... This is only speculation!
« Last Edit: 22/04/2011 08:35:33 by CPT ArkAngel »
 

Offline Geezer

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« Reply #43 on: 22/04/2011 08:31:20 »
So which one of those two is more real? Time dilation or Lorentz contraction?

I am wondering about that for more that 2 months now... One thing is sure, it is that you cannot have both in the same equation. Probably, the answer is that space and time are indivisible...

I am utterly clueless when it comes to the math, but my wild guess is that you are right. It's not a surprise that we base our science on our perspective, but what would the science of a particle zipping along through "our" space be?

Would it be completely different?
 

Offline CPT ArkAngel

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« Reply #44 on: 22/04/2011 09:08:40 »
interactions from a fifth dimension: the electric charge ???
 

Offline yor_on

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« Reply #45 on: 22/04/2011 09:19:08 »
Hm, I'm afraid I went overboard a little here :)

Weird stuff, SpaceTime, Quantum mechanics too. Don't know which one is weirdest in fact? But so are Maxwell's equations,. Electromagnetic 'fields'? Charge? No wonder that Tesla found his ideas 'normal' :) using Earth as a resonator, expecting to get more energy out than he put in as his waves would start to build up a self-sustained oscillation, that he expected to be amplified, and some actually say they was too? I wonder what he would have made of what we believe us to know today? We say that he was, eh, misinformed? But if someone had told him and Maxwell, and Newton, about QM and SpaceTime I wonder what they would have done?

Called for a doctor?

ahem :)
 

Offline JP

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« Reply #46 on: 22/04/2011 14:16:31 »
So which one of those two is more real? Time dilation or Lorentz contraction?

I am wondering about that for more that 2 months now... One thing is sure, it is that you cannot have both in the same equation. Probably, the answer is that space and time are indivisible...

I am utterly clueless when it comes to the math, but my wild guess is that you are right.

Yeah, dealing with the effects of speed on only space or time was always confusing for me.  As far as learning what the transformations should look like mathematically, separating them makes sense, but as far as making the equations elegant, writing them together is the way to go.

Once you do that, you see that the fundamental equation is a Lorentz boost, which takes a vector in space-time coordinates and tells you how that whole vector changes when you change speed, i.e. how space and time coordinates of an event change.  It's actually just a simple matrix multiplication:  http://en.wikipedia.org/wiki/Lorentz_transformation#Matrix_form
 

Offline sciconoclast

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« Reply #47 on: 23/04/2011 01:02:00 »
JP
  You stated in your interpretation of Coleman; " Now back to what Coleman is saying.......you generate statistics that don't have a classical hidden variables cause."

How can you reconcile that with Coleman's statement near the end ( around 61minutes ) that what is involved is " definite quantum states completely determined by initial conditions that never the less appear to be the result of randomness".

You can't back out of this lecture after the first half or you will miss the conclusions.
 

Offline JP

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« Reply #48 on: 23/04/2011 01:42:24 »
As Coleman says, it's a "quantum state completely determined by initial conditions."  As I said, this quantum state generates "statistics that don't have a classical hidden variables cause." 

In other words, the initial setup of this state is "entangled" which is purely a quantum phenomenon.  The rules to then propagate it to distant observers are entirely deterministic. 

Coleman's final point about things appearing "to be the result of randomness," is about how you think about measurements.  The Copenhagen interpretation is to think of them as collapsing the wave function, which introduces randomness.  Coleman seems to be arguing that if you view the observer as a quantum object as well, that there is no need to introduce randomness, which is true.  I think it's a bit confusing to introduce this interpretation when trying to focus on entanglement. 

Let's go back to a concrete example here so maybe we can see where we disagree.  Do you agree that the GHZ state that Coleman brings up produces results that can't be explained with classical hidden-variable models?
« Last Edit: 23/04/2011 01:48:22 by JP »
 

Offline sciconoclast

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« Reply #49 on: 25/04/2011 15:41:37 »
JP: we might be on the same page now.
Your statement that, "The rules to then propagate to distant observers are entirely deterministic.", reads like something I might write.

Under that interpretation; would it be correct to state that a measurement of a particle by one distant observer would not affect the other particle or the other distant observers results.   Would it also be correct that there is no single, composite non-locality incorporating both particles as they propagate to distant observers.
 

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