https://www.yahoo.com/news/entangled-particles-reveal-even-spookier-action-t... [partial quote] Sorry, Einstein: It looks like the world is spooky — even when your most famous theory is tossed out.This finding comes from a close look at quantum entanglement, in which two particles that are "entangled" affect each other even when separated by a large distance. Einstein found that his theory of special relativity meant that this weird behavior was impossible, calling it "spooky."Now, researchers have found that even if they were to scrap this theory, allowing entangled particles to communicate with each other faster than the speed of light or even instantaneously, that couldn't explain the odd behavior. The findings rule out certain "realist" interpretations of spooky quantum behavior. [Infographic: How Quantum Entanglement Works]"What that tells us is that we have to look a little bit deeper," said study co-author Martin Ringbauer, a doctoral candidate in physics at the University of Queensland in Australia. "This kind of action-at-a-distance is not enough to explain quantum correlations" seen between entangled particles, Ringbauer said. Action at a distance Most of the time, the world seems — if not precisely orderly — then at least governed by fixed rules. At the macroscale, cause-and-effect rules the behavior of the universe, time always marches forward and objects in the universe have objective, measurable properties. But zoom in enough, and those common-sense notions seem to evaporate. At the subatomic scale, particles can become entangled, meaning their fates are bizarrely linked. For instance, if two photons are sent from a laser through a crystal, after they fly off in separate directions, their spin will be linked the moment one of the particles is measured. Several studies have now confirmed that, no matter how far apart entangled particles are, how fast one particle is measured, or how many times particles are measured, their states become inextricably linked once they are measured.For nearly a century, physicists have tried to understand what this means about the universe. The dominant interpretation was that entangled particles have no fixed position or orientation until they are measured. Instead, both particles travel as the sum of the probability of all their potential positions, and both only "choose" one state at the moment of measurement. This behavior seems to defy notions of Einstein's theory ofspecial relativity, which argues that no information can be transmitted faster than the speed of light. It was so frustrating to Einstein that he famously called it "spooky action at a distance." To get around this notion, in 1935, Einstein and colleagues Boris Podolsky and Nathan Rosen laid out a paradox that could test the alternate hypothesis that some hidden variable affected the fate of both objects as they traveled. If the hidden variable model were true, that would mean "there's some description of reality which is objective," Ringbauer told Live Science. [Spooky! The Top 10 Unexplained Phenomena]Then in 1964, Irish physicist John Stewart Bell came up with a mathematical expression, now known as Bell's Inequality, that could experimentally prove Einstein wrong by proving the act of measuring a particle affects its state.In hundreds of tests since, Einstein's basic explanation for entanglement has failed: Hidden variables can't seem to explain the correlations between entangled particles.But there was still some wiggle room: Bell's Inequality didn't address the situation in which two entangled photons travel faster than light.[end of partial quote]
On Fri, Sep 16, 2016 at 10:13 PM, jim bell <jdb10987@yahoo.com> wrote:
https://www.yahoo.com/news/entangled-particles-reveal- even-spookier-action-thought-125723794.html <https://www.yahoo.com/news/entangled-particles-reveal-even-spookier-action-thought-125723794.html?soc_src=mail&soc_trk=ma>
I'm by no means an expert in quantum physics, which makes my lack of surprise at this fairly uninteresting, but it seems to me these results are completely compatible with the time-symmetric interpretation of quantum mechanics. If I understand it correctly, according to TSQM the particle already "knows" about its future interactions to the extent that quantum information is preserved through any intervening interactions. So in the case of photon-splitting, the photons leave their source with polarizations that are aligned with (or opposite) the axis on which they will be measured. You could say the information "propagates" in both temporal directions, but I think it makes more sense to think of the particle's entire timeline as a single entity. According to the papers I've read on TSQM, it makes (or made) no predictions that are different from the Copenhagen interpretation. This experiment seems like it may be the first to show a difference. Not necessarily because of any predictions, but because of the additional mental contortions required to hang on to the Copenhagen interpretation. There's still no ability to send "real" information faster than light or backward in time, though. I say this only because of the purported equivalence between TSQM and Copenhagen, not because I have any idea why it should be the case. Intuitively, it seems like it could be related to the (quantum) information-theoretic version of entropy that you get with reversible computations. Or maybe even just real entropy, since TSQM still "behaves" as if it's nondeterministic from our perspective, since we can never know enough about a system to know its "true" internal state. So somehow everything conspires to prevent us from setting up a system that would carry some piece of information back in time that we care about. I guess another way to look at it is that the universe is a solution to some kind of differential equation. Possible solutions that contain paradoxes aren't valid, so they don't happen. Not via some shift in some "unified" timeline ala Star Trek, but through colossal numbers of tiny shifts that disperse any information that we're trying to send back in time that would cause any kind of paradox at any scale. The result is a universe that appears to have an arrow of time at any scale we can actually measure, appears to mostly follow General Relativity, etc. Until you get to scales, large and small, where the exact underlying geometry starts to matter. Come to think of it, if paradoxes are what's important, the ability to send information back in your own timeline (i.e. within your own past light cone) is all that matters. If there is no privileged reference frame, this also means you can't send information into spacelike regions of your own light cone, because if two entities do that then you can arrange things to send information into your own past light cone. But if there IS a privileged reference frame, say, the reference frame of the CMB, where you can't send information into *its* past light cone, then you can send information faster than light but still not into your own past. Recall that the Lorentz transformations were initially introduced to (successfully) explain how light could appear to always be moving the same speed even with a luminiferous ether, but then Einstein discarded the luminiferous ether because he realized it wasn't necessary, not because there was any evidence that contradicted it. I may well be misinterpreting what TSQM says, so please don't discard it on the basis of my uninformed interpretation! Go read up on it and THEN discard it ;-) http://jamesowenweatherall.com/SCPPRG/AharonovPopescuTollaksen2010PhysToday_...
On Sat, Sep 17, 2016 at 05:13:18AM +0000, jim bell wrote:
https://www.yahoo.com/news/entangled-particles-reveal-even-spookier-action-t...
[partial quote] Sorry, Einstein: It looks like the world is spooky ??? even when your most famous theory is tossed out.This finding comes from a close look at quantum entanglement, in which two particles that are "entangled" affect each other even when separated by a large distance. Einstein found that his theory of special relativity meant that this weird behavior was impossible, calling it "spooky."Now, researchers have found that even if they were to scrap this theory, allowing entangled particles to communicate with each other faster than the??speed of light??or even instantaneously, that couldn't explain the odd behavior. The findings rule out certain "realist" interpretations of spooky quantum behavior. [Infographic: How Quantum Entanglement Works]"What that tells us is that we have to look a little bit deeper," said study co-author Martin Ringbauer, a doctoral candidate in physics at the University of Queensland in Australia. "This kind of action-at-a-distance is not enough to explain quantum correlations" seen between entangled particles, Ringbauer said. Action at a distance Most of the time, the world seems ??? if not precisely orderly ??? then at least governed by fixed rules. At the macroscale, cause-and-effect rules the behavior of the universe,??time always marches forward??and objects in the universe have objective, measurable properties. ??But zoom in enough, and those common-sense notions seem to evaporate. At the subatomic scale, particles can become entangled, meaning their fates are bizarrely linked. For instance, if two photons are sent from a laser through a crystal, after they fly off in separate directions, their spin will be linked the moment one of the particles is measured. Several studies have now confirmed that, no matter how far apart entangled particles are, how fast one particle is measured, or how many times particles are measured, their states become inextricably linked once they are measured.For nearly a century, physicists have tried to understand what this means about the universe. The dominant interpretation was that entangled particles have no fixed position or orientation until they are measured. Instead, both particles travel as the sum of the probability of all their potential positions, and both only "choose" one state at the moment of measurement. This behavior seems to defy notions of Einstein's theory ofspecial relativity, which argues that no information can be transmitted faster than the speed of light. It was so frustrating to Einstein that he famously called it "spooky action at a distance."??To get around this notion, in 1935, Einstein and colleagues Boris Podolsky and Nathan Rosen laid out a paradox that could test the alternate hypothesis that some hidden variable affected the fate of both objects as they traveled. If the hidden variable model were true, that would mean "there's some description of reality which is objective," Ringbauer told Live Science. [Spooky! The Top 10 Unexplained Phenomena]Then in 1964, Irish physicist John Stewart Bell came up with a mathematical expression, now known as Bell's Inequality, that could??experimenta
Interesting experiment shows "Quantum teleportation was just achieved over more than 7 km of city fibre".. Independent teams in China and Canada just showed... something interesting, "sending" quantum information over existing fiber networks in Calgary and Hefei (China)... Still parsing the story, but it seems to have definite implications for crypto. sources: https://science.slashdot.org/story/16/09/20/222232/quantum-teleportation-ach... http://www.sciencealert.com/quantum-teleportation-was-just-achieved-over-7-k... http://www.nature.com/nphoton/journal/vaop/ncurrent/full/nphoton.2016.180.ht... http://www.nature.com/nphoton/journal/vaop/ncurrent/full/nphoton.2016.179.ht... John
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Sean Lynch