questionposter Posted April 18, 2012 Posted April 18, 2012 (edited) If I have two particles and I separate them by many light years, one on Earth and one near a black hole, since their states would be instantly determined by any measurement via their inherent mathematics, wouldn't I instantaneously break the entanglement even in far different time dilations to any frame of reference (granted that I am not considered the actual light that would need to travel to a measuring device)? Edited April 18, 2012 by questionposter
Schrödinger's hat Posted April 18, 2012 Posted April 18, 2012 If I have two particles and I separate them by many light years, one on Earth and one near a black hole, since their states would be instantly determined by any measurement via their inherent mathematics, wouldn't I instantaneously break the entanglement even in far different time dilations to any frame of reference (granted that I am not considered the actual light that would need to travel to a measuring device)? What you are describing is essentially the epr paradox. The key thing to remember about measurements on entangled particles is that you have a pair of events that are correlated, but have no detectable causal relationship to one another. As such, whether or not you view there to be an effect from one measurement on the other depends on your interpretation of QM. Within the Copenhagen and objective collapse interpretations, there is an instantaneous, non-local effect, but this effect cannot be used to transfer any information without presently unknown and un-detected non-linearities in the theory. Within certain variants of the many worlds, there is no such non-local occurence, the measurement is instead the operation of the measurer becoming entangled with one of the possible universes, so when they return and communicate with the other measurer, they will find a correlated result. 1
questionposter Posted April 18, 2012 Author Posted April 18, 2012 (edited) What you are describing is essentially the epr paradox. The key thing to remember about measurements on entangled particles is that you have a pair of events that are correlated, but have no detectable causal relationship to one another. As such, whether or not you view there to be an effect from one measurement on the other depends on your interpretation of QM. Within the Copenhagen and objective collapse interpretations, there is an instantaneous, non-local effect, but this effect cannot be used to transfer any information without presently unknown and un-detected non-linearities in the theory. Within certain variants of the many worlds, there is no such non-local occurence, the measurement is instead the operation of the measurer becoming entangled with one of the possible universes, so when they return and communicate with the other measurer, they will find a correlated result. I don't think this is a "its whatever answer you want" type of question though, I think this is a specific scenario that could even be tested one day. And like you were describing, information wouldn't be "transferred". According to the mathematics, two entangled particles "are" the same particle and thus information is not being sent between two objects, but rather there is just the undetirmination and determination of the single state of a single object which consists of entangled particles, and that doesn't break relativity. Edited April 18, 2012 by questionposter
Schrödinger's hat Posted April 18, 2012 Posted April 18, 2012 (edited) I don't think this is a "its whatever answer you want" type of question though, I think this is a specific scenario that could even be tested one day. The EPR paradox is a scenario that can be (and to some degree has been) tested. The results so far agree with the predictions made by the mathematics, but there are multiple valid interpretations of the mathematics. All interpretations (with no extension to quantum mechanics) require that this phenomenon be unable to transfer information. Many worlds preserves locality, but implies the existence of the many universes that give it its name. Copenhagen only entails a single universe, but requires the wavefunction collapse to be a non-local phenomenon. The situation could be viewed as roughly analogous to the gauge choice in electromagnetism. The coulomb gauge is fully compatible with observation and preserves causality, but entails fields which change non-locally and instantaneously, whereas the lorentz gauge does not. Relativity gives us a clear reason to prefer the Lorentz gauge (for metaphysical purposes at least; the Coulomb gauge is still quite useful for making predictions/modelling things), whereas there is still debate over which interpretation of quantum physics should be considered simplest (and a large camp of people who consider it a largely irrelevant question and say we should just get on with making better mathematical theories because some later discovery will likely later render whatever ontology we come up with irrelevant anyway). Edited April 18, 2012 by Schrödinger's hat 2
D H Posted April 18, 2012 Posted April 18, 2012 I don't think this is a "its whatever answer you want" type of question though, I think this is a specific scenario that could even be tested one day. Entanglement and Bell's Theorem have been tested, many times over. There are some loopholes to some of the nasty implications that require you to throw out something rather important such as locality or counterfactual definiteness, but these loopholes are being closed one by one and are now rather slim. Schrödinger's hat did not say "its whatever answer you want". He was referring to various interpretations of quantum mechanics. All viable interpretations yield exactly the same answer to every experiment conducted so far, so in a sense it doesn't matter one bit which way you look at things. However, these interpretations color the way one looks at the universe. None of these interpretations is something with which we humans are quite comfortable. The Copenhagen interpretation is an offshoot of the 1920s Germany. It's chock full of bits of logical positivism. It is more than a bit autistic ("does the Moon exist when we don't look at it?") and is non-realistic. Many worlds is an offshoot of the 1960s America. Psychedelic. 2
questionposter Posted April 18, 2012 Author Posted April 18, 2012 (edited) I already know entanglement is tested, I mean actually traveling near a black hole, which I don't think we have the technology to do right now, and I already know information isn't transferred, but the interaction itself should be instantaneous to all points of reference shouldn't it? I don't see why it wouldn't especially considering there aren't two objects to transfer information between and thus not break relativity... I guess I could see how many-worlds could arise from the paradox, but I thought even Stephan Hawking said that paradoxes don't exist in reality. Ex: What came first the chicken or the egg? Not a paradox, the egg came first because the egg was laid by a slightly different species, in other worlds, evolution. Edited April 18, 2012 by questionposter
Schrödinger's hat Posted April 19, 2012 Posted April 19, 2012 and is non-realistic. Elaborate on what you mean by this? Also elaborate on what Copenhagen interpretation means to you My understanding is it's a bit of an umbrella term that includes some types of objective collapse, consciousness causes collapse nonsense, and stuff involving modification of how we think about whether certain statements are true/false (ie. consistent histories). 1
D H Posted April 19, 2012 Posted April 19, 2012 (edited) Elaborate on what you mean by this? The Copenhagen interpretation describes what we can expect in terms of an experimental outcome. Whether that means anything about a larger "reality": The Copenhagen interpretation doesn't care. The CI takes an instrumentalist (aka non-realistic, as opposed to realistic or anti-realistic) point of view. Another way to say it: "Shut up and calculate". Also elaborate on what Copenhagen interpretation means to you "Shut up and calculate." There are no hidden variables. The ket isn't quite real. The collapse of the wavefunction is what counts. "Does the moon exist if we don't look at it" is a nonsense question. Edited April 19, 2012 by D H 1
Schrödinger's hat Posted April 19, 2012 Posted April 19, 2012 The Copenhagen interpretation describes what we can expect in terms of an experimental outcome. Whether that means anything about a larger "reality": The Copenhagen interpretation doesn't care. The CI takes an instrumentalist (aka non-realistic, as opposed to realistic or anti-realistic) point of view. Another way to say it: "Shut up and calculate". "Shut up and calculate." There are no hidden variables. The ket isn't quite real. The collapse of the wavefunction is what counts. "Does the moon exist if we don't look at it" is a nonsense question. Everywhere else I've read about it, this was called something along the lines of the statistical, ensemble, minimalist, or Born interpretation and the phrase 'Copenhagen interpretation' was reserved for the idea that the process of measurement altered something non-locally that was part of reality. Do you have some sources for further reading?
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