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Arguments Regarding Spooky and Action at a Distance Arguments Regarding Spooky and Action at a Distance Sanjay Srikumar University of Maryland 2019 Abstract The phrase “Spooky and Action at a Distance” was coined by Albert Einstein to describe the nuances in the theory of quantum entanglement. This paper considers two views: one for action at a distance and one against. Several researchers have attempted to tackle this issue with experiments with a variety of results. Although neither stance is entirely sound, arguments stemming from Bell’s Theory for Spooky Action at a Distance are the most accurate. Keywords: quantum entanglement, nonlocality, action at a distance, superluminal, speed-of-light 1 Introduction From the Einstein-Podolsky-Rosen Argument [1], the authors provide an understanding of the fundamental protocol known as quantum entanglement. One finds that if we have an entangled pair of particles x and y, the measurement of y somehow influences the measurement of x. It is, however, important to note that the act of measuring the particles themselves have no bearing on the particles quantitative. Instead the measurement of one quality inherently implies uncertainty about the other characteristics. In other words, measuring a +1 spin on one entangled particle means a –1 spin on its counterpart. 2 Reichenbach’s Principle In Reichenbach’s Common Cause Principle [2], Author Hans Reichenbach discusses the two ways correlations may arise. Applied to the case of entangled particles, Reichenbach’s principle states that entanglement is either the result of a common history or some interaction at a distance. To see this, consider the case of two entangled particles A and B, which yield identical spin measurements. Using Reichenbach’s principle, we can explain this correlation by stating that both particles came from the same source, and thus were created identically. Similarly, we can state that somehow the spin of one particle affects the spin of the other through interaction. In the case of quantum entanglement, it turns out that this common cause explanation has been ruled out due to Bell’s theorem. 3 Bell’s Theorem- An Argument For Action at a Distance One of the biggest breakthroughs in quantum entanglement came from John Stewart Bell in his 1964 paper titled “On the Einstein Podolsky Rosen Paradox” [3] in which he proposed a theory asserting that the world is nonlocal. This means that there exist interactions between events (or particles) that are too close temporally and too far spatially for the events to be related in a way that coincides with Einstein’s theory of relativity. As a result, Bell resorts to the idea of superluminal interaction to explain such phenomena as quantum entanglement. This theory has only been bolstered in recent years, as researchers have tested and measured the speed at which entangled particles must communicate. While concerns about the theory still remain prominent in the scientific community, as it inherently defies other theories of physics, it appears that Bell’s argument is the most logical. Although this may seem like a false dichotomy, no other theories have arisen that introduce a plausible explanation for the unique phenomenon of entanglement. 3.1 Evidence of Nonlocality - East-West Village Experiment Proponents for spooky action at a distance ––Daniel Salart, Augustin Baas, Cyril Branciard, Nicolas Gisin, and Hugo Zbinden–– made an important discovery as they were testing the speed of ‘spooky action at a distance’ [4]. As the authors state, they “performed a Bell test [...] between two villages separated by 18 km and approximately east–west oriented, with the source located precisely in the middle.” The researchers then set a lower bound and upper bound, and were able to confirm the nonlocality observed in previous experimental ventures. In layman's terms, they found that the interactions occur faster than the speed of light. This experiment proves that there is indeed something bizarre going on. Most importantly, however, is that it shows that one of our assumptions about quantum mechanics as a whole is incorrect. In line with Bell’s theory, I find that Einstein’s theory of relativity, in which nothing can exceed the speed of light, is incomplete. 3.2 Evidence of Nonlocality - East-West Lake Experiment Similarly, in a paper titled "Bounding the Speed of ‘Spooky Action at a Distance’” [5] by Juan Yin and others, researchers attempted to calculate the speed of ‘spooky action’, also known as communication between entangled particles, based on measured findings. In an East-West 12 hour Bell test, the researchers sent entangled photon pairs across the Qinghai Lake region at a distance of 15.3 kilometers. They found their lower bound to be four times the speed of light, supporting the idea of non-locality founded in Bell’s theory and comparably proved in the previous experiment. 4 Disagreement And Concerns With Bell’s Theory Regardless of these findings, this recurring theme of superluminal communication, which stems from Non-Locality, has its caveats. One of the biggest is that superluminal communication is completely speculative: in other words, it has never been observed in real life. It is at this point at which researchers begin to disagree: many scholars find Bell’s theory to be a plausible logical explanation while others stand behind Einstein’s theory of Relativity, in which nothing can exceed the speed of light. 5 Theory of Relativity- An Argument Against Action at a Distance Einstein's theory of relativity [6] is only strengthened by the fact that no one has actually found a way to use entanglement to communicate faster than light. Moreover, overturning relativity has implications that would tear apart our very understanding of the physical universe. For one, introducing superluminal interactions implies that entanglement could be used to transmit information to the past, which leads to logical and causal paradoxes (like the grandfather paradox). Relativity is the basic protocol for all physics, and overturning it is not something that should be done without a clear and substantial reason. More likely than not, relativity is simply incomplete rather than incorrect, as the math and logic behind Einstein’s argument seems valid. 5.1 Evidence Against the Proposal of Superluminal Communication Researchers Falk Unger and others wrote a paper called “Limit on Nonlocality in Any World in Which Communication Complexity Is Not Trivial” [7] in which they assert that superluminal interactions are impossible, therefore Relativity remains intact. They conclude that “in any world in which communication complexity is nontrivial, there is a bound on how much nature can be nonlocal.” This directly contradicts Bells theory, where his argument is rooted in a completely Non-local world. 6 Conclusion The arguments for and against spooky action at a distance are evidently rooted in math and science, and there isn’t necessarily an incorrect theory to explain the phenomenon that subverts quantum mechanics. However, given these two arguments, it is clear that Bell’s theory comes from a place of logic while Einsteins comes from a place of credibility. Should the superluminal communication described in Bells theory become possible, it will abide by some of the guidelines set in Einstein's Theory of Relativity, almost as if entangled particles have a private communication pathway that is unusable by anything that is not entangled with that same system. The theories covered in this paper to explain Spooky Action at a Distance are the most credible arguments available at this time, and will remain as such until further research is completed. References: [1] Rosen, N. (1979). Can Quantum-Mechanical Description of Physical Reality Be Considered Complete? Albert Einstein, 57–67. doi: 10.1007/978-3-322-91080-6_6 [2] Hofer-Szabo, G., Redei, M., & Szabo, L. E. (n.d.). Reichenbachs Common Cause Principle and EPR correlations. The Principle of the Common Cause, 134–172. doi: 10.1017/cbo9781139094344.010 [3] Bell Theorem. (2019). Do We Really Understand Quantum Mechanics?, 73–116. doi: 10.1017/9781108569361.007 [4] Salart, D., Baas, A., Branciard, C. et al. Testing the speed of ‘spooky action at a distance’. Nature 454, 861–864 (2008) doi:10.1038/nature07121 [5] Juan, Cao, Yuan, Yong, Hai-Lin, Ren, … Jian-Wei. (2013, June 18). Bounding the speed of `spooky action at a distance'. Retrieved from https://arxiv.org/abs/1303.0614. [6] Born, M. (2010). Einsteins theory of relativity. Lexington, KY: Forgotten Books. [7] Brassard, G., Buhrman, H., Linden, N., Méthot, A. A., Tapp, A., & Unger, F. (2006). Limit on Nonlocality in Any World in Which Communication Complexity Is Not Trivial. Physical Review Letters, 96(25). doi: 10.1103/physrevlett.96.250401 [8] Eberhard, P. H., & Ross, R. R. (1989). Quantum field theory cannot provide faster- than-light communication. Foundations of Physics Letters, 2(2), 127–149. doi: 10.1007/bf00696109 .
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