PAllen's latest activity
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PPAllen replied to the thread I Intrinsic curvature.The sectional curvature as described can be directly related to the Riemann tensor as written in terms of the metric. BUT, for...
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PPAllen replied to the thread I Intrinsic curvature.Note, there are other ways to define intrinsic curvature constants. For example, consider the area of a small circle on the surface of a...
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PPAllen replied to the thread I Synchronizing clocks in an inertial frame if light is anisotropic.I would think of that more like the case of lightlike coordinates. That a time coordinate is the same along a null path in some...
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PPAllen replied to the thread I Question about Parallel Transport.Ok, yes, I don't see a reason you couldn't apply the definition in a Riemannian manifold - books just assume a timelike curve. For the...
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PPAllen replied to the thread I Question about Parallel Transport.Yes, not the best choice of words.
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PPAllen replied to the thread I Question about Parallel Transport.I've generally seen FW transport only defined along timelike curves, so that definition would simply not apply to Riemannian manifolds...
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PPAllen replied to the thread I Question about Parallel Transport.I disagree. The definition of a geodesics as a curve that parallel transports its tangent vector makes no sense without parallel...
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PPAllen replied to the thread B Inflation after Atacama Cosmology Telescope Results.I would say no change to the status of any inflation aimed at ‘explaining’ the standard model initial state, since the conclusion is to...
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PProposition: the square root of a positive integer is either an integer or irrational (it cannot be a proper rational). Proof (by...
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PPAllen replied to the thread How do people explore new ideas in physics?.A little off topic, but since I alluded to Faraday's long apprenticeship with Sir Humphrey Davy that acted as bridge from self teaching...
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PPAllen replied to the thread How do people explore new ideas in physics?.Wrong. He did a long apprenticeship with Sir Humphrey Davy (president of the Royal Society, world famous chemist) before his work on EM...
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PPAllen replied to the thread Latex help page not rendering.The problem is (mostly?) fixed now. Just tested it.
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Phttps://en.wikipedia.org/wiki/Yvonne_Choquet-Bruhat (photo from 1974) https://www.nature.com/articles/d41586-025-01763-z...
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PPAllen replied to the thread I Physicists disagree wildly on what quantum mechanics says about real….I’d never seen that one. At first glance, I like it. Now, I have dig in to determine whether I can believe it …
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PRefer to the original diagram in post #1. Fact: The hanging mass on the left is and remains at rest. This means that the tension in the...
