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Must every point in spacetime remain attached to its current neighbours? Basically yes, this captures the spirit of allowable deformations. Some background: If you want to measure distances between points, this is very much in the realm of mathematical analysis. However, it is sometimes useful to be able to discuss "closeness" in a looser (but still ...


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You need to be careful about comparing the curvature of spacetime to the deformation of a block of jelly. In particular, in general relativity time is curved as well as space, and this is impossible to represent with the jelly model. In fact it's just about impossible to give a really good description of spacetime curvature to anyone who doesn't have at ...


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According to classical mechanics the electrons moving outside an infinite solenoid do not feel the magnetic field. This is because the force they experience, according to the Lorentz law, depends only on the fields and not on the potentials. Thus according to classical mechanics the electrons beams passing from the different sides of the solenoid will move ...


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Intuitive answer: Keep in mind that in three dimensions you can have point (no dimension) and line (1D) defects. If you mean line defects, you're right, $2\pi$ line defects are unstable (although $2\pi$ point defects are stable). In a 2D nematic, only point defects are possible and you're also right: a $2\pi$ disclination in a 2D nematic is stable (in the ...



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