According to Quantum Mechanics it is possible for two particles to become 'entangled' --- so that any change to one particle is instantaneously transmitted to the other, causing a corresponding change in the other particle. Supposedly it doesn't matter whether the two particles are a few feet apart, or a million light-years apart.
Albert Einstein rejected the concept. To him it implied something 'spooky.' Experiments have seemed to support the idea, however.
But I seem to see a 'fly in the ointment,' as it were. I am sure someone more knowledgeable can resolve my difficulty and show me where I am wrong.
First let me preface my remarks by saying that I understand Quantum Mechanics to be all about observers, predictions and experimental design. Anything, therefore, which is attributed to Quantum Mechanics but which goes beyond those three considerations is --- in my humble opinion --- mere speculation.
In particular, when we talk about how Quantum Entanglement requires that two particles millions of light years apart can communicate changes instantaneously, we seem to be engaging in mere speculation.
And as long as we acknowledge that we are engaging in mere speculation, I would point out that I have an alternative explanation for the phenomenon.
My explanation is this... Not only are the two particles entangled, but the whole experimental design is entangled with them. It is impossible to separate the particles from the observers, or from the experiment. The instantaneous changes observed in experimental situations are caused by the experiment, itself.
Seen in such a light there is nothing spooky involved. Nor is there any need to fantasize how changes can be instantaneously transmitted across millions of light-years of 'empty space.' For there is no conceivable experimental design spanning those millions of light-years.
The same sort of argument, of course, can probably be applied to all the fuzziness involved in Quantum Mechanics. All of it can probably be attributed to the limitations of experimental design.
Undoubtedly better minds than mine have thought through all that I am saying here and have seen how wrong I am. Such a consideration could not have escaped Albert Einstein, Neils Bohr, and the other giants of modern physics. So why am I wrong?
Perhaps a 'positivist' would say I am simply wrong because I am speculating about what can not be understood in experimental terms. To that I would respond that they seem also seem to be speculating about the very same things. Why is their speculation better than mine?
"sound is heard by us at the place it is generated" Surely, don't you mean that it is "heard" at the place it is ***perceived***? We can *locate* the putative origin with reasonable accuracy by correlating information from each ear, but this would rather be "hearing the sound AS IF it were generated in a certain place".
The problem of entanglement is a problem of instantaneous communication between points that are spacelike separated. One could just as well ask whether the particles are "actually" spacelike separated (if "spacetime" is relational rather than absolute, can we say with certainty that the particles ARE spacelike separated?).
The many-world interpretation would allow that there are worlds corresponding to Alice's reading of +z and to her reading of -z; in accessible worlds, where Alice reads +z Bob reads -z and vice versa (here, a world W1 is "accessible" to another world W1 when the same general physical conditions obtain in both W1 and W2. A world where both Alice and Bob read +z would be inaccessible from ours as the same general physical conditions would not obtain). Here, the question is "which" world Alice and Bob actually occupy: imagine that Alice reads +z in W1 and –z in W2. If the reading is made at T, and disallowing hidden variables, W1 and W2 can only be differentiated at T and thereafter; at all times
ST: "We assume that particles spatially separated by any distance can get entangled because if particles two feet apart can get entangled without any apparent physical link between them then there is no reason why particles separated by thousands of light years should not get entangled."
But there are physical links. I am sitting here in my office, but there are electromagnetic forces that bind me to all the objects around me.
And you and I are likewise linked by the internet, an electronic grid that encircles the world 24 hours a day.
You may assume what you want, but Quantum Mechanics can't have it both ways. If the presence of an observer is sufficient to cause a wave form to 'collapse' then the observer is partly responsible for the result of the collapse. It is the observer as much as the wave form that determines the final state.
DH: "The problem of entanglement is a problem of instantaneous communication between points that are spacelike separated.
I'm not necessarily concerned by the idea of instantaneous communication. It clearly does cause a problem for those who say that there is no absolute synchrony in nature.
My real concern is that there are simpler explanations for the observed phenomena. If as I think possible, the observers are entangled with their observations, then one can not eliminate their influence on the result.
"If as I think possible, the observers are entangled with their observations, then one can not eliminate their influence on the result."
Unless I'm entirely off the track here, in the EPR thought-experiment there is a "point of origin" for the entangled particles - and the quantum state of the spin singlet depends on the particles having been emitted from this point of origin.
Couldn't we argue that the entire universe has a common "point of origin" and that perhaps the whole damn thing's in a "state of entanglement"?
Once again, I'm obliged to state my ignorance of the technical details; but one thing I've found in my discussions with the more scientific bods is that - for all the sophistication of their mathematical formulations - when they talk about the extra-theoretical implications, they fall back on the good old intuitive 3+1D view of the world. The ONLY value "philosophers of time" have is that we worry about how "formal concepts" can be expressed in "everyday language" - particularly bearing in mind that, as a species, we humans developed language in order to tell the other monkeys where the ripe fruit was (or wasn't, which was the dawn of "intelligence").
DH: "Couldn't we argue that the entire universe has a common "point of origin" and that perhaps the whole damn thing's in a 'state of entanglement?'"
I suppose that makes sense. But what do we gain from such an idea?
Dear Bill,
I agree with your skepticism and that we should first pursue the simpler explanation. Considering the reputation Quantum Mechanics has as far as being logically consistent in its theory we should indeed be skeptical. Why isn't this just an effect of the observation ? And, David, if we do argue that the whole universe is in some way entangled, which I think we shouldn't initially ( Not necessariy everything being entangled but entanglement occurring in nature on a broad scale (?)), it should be to reach some contradiction or just to explore the situation philosophically to test some of its limits.
Sincerely,
Oliver Kayende
As I understand it, Werner Heisenberg initially justified his Uncertainty Principle saying that the observer can not be separated from his observation... And the Copenhagen Interpretation places great emphasis on the role of the observer. So why do scientists forget that role when it comes to understanding entanglement?
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