PeterDonis's latest activity
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PeterDonis replied to the thread Graduate Is the variation of the metric ##\delta g_{\mu\nu}## a tensor?.Then you should post them directly using LaTeX for equations, in accordance with the forum rules. We can't if all we can quote is an... -
PeterDonis replied to the thread Graduate Is the variation of the metric ##\delta g_{\mu\nu}## a tensor?.What reference is this screenshot from?
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PeterDonis replied to the thread Undergrad Gauss' law seems to imply instantaneous electric field propagation.Thread closed for moderation.
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PeterDonis replied to the thread A three month long summer vacation from public school seems stupid.It was still the same schedule in Virginia in the late 1970s and early 1980s when I went to school there. Most houses had AC by that...
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PeterDonis replied to the thread Undergrad Question about discussions around quantum interpretations.I think you have it somewhat backwards. In a typical quantum experiment, we prepare a system, it goes through some kind of process, and...
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PeterDonis reacted to Orodruin's post in the thread Undergrad How Is Intrinsic Curvature Measured in Higher Dimensions Like 4D Spacetime? with
Like.
I believe that is intrinsically applying the Levi-Civita connection as the geodesics of the Levi-Civita connection are the paths that... -
PeterDonis reacted to Nugatory's post in the thread Undergrad Synchronizing clocks in an inertial frame if light is anisotropic with Like.
Does that force us to deal with clock synchronization? Start with a source of light signals and a mirror, move the mirror around until...
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PeterDonis reacted to Nugatory's post in the thread Undergrad How Is Intrinsic Curvature Measured in Higher Dimensions Like 4D Spacetime? with Like.
When @geordief wrote that he was still under the misunderstanding that “I think parallel transport relies on these tangent planes [that...
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PeterDonis replied to the thread Undergrad Gauss' law seems to imply instantaneous electric field propagation.Moderator's note: Posts from the second thread the OP started on the same topic have been moved to this thread. @Bob44 there is no need...
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PeterDonis replied to the thread Undergrad Synchronizing clocks in an inertial frame if light is anisotropic.I don't think distance itself is something in people's heads. But definitions of units of distance are. As you note, the SI definition...
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PeterDonis reacted to PAllen's post in the thread Undergrad How Is Intrinsic Curvature Measured in Higher Dimensions Like 4D Spacetime? with Like.
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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PeterDonis replied to the thread Undergrad Schrödinger equation and classical wave equation."I've heard" is not a valid reference. If you can give us references to actual textbooks or peer-reviewed papers that make statements...
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PeterDonis replied to the thread Undergrad Schrödinger equation and classical wave equation.Again, there's a lot in your post #1, and I'm not sure which question you're talking about. I only confirmed that ##\Psi## is a...
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PeterDonis reacted to Nugatory's post in the thread Undergrad How Is Intrinsic Curvature Measured in Higher Dimensions Like 4D Spacetime? with Like.
They aren't "on" the sphere anywhere. There is a mapping from each point on the surface of the sphere to a two-dimensional vector space...
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PeterDonis replied to the thread Undergrad How Is Intrinsic Curvature Measured in Higher Dimensions Like 4D Spacetime?.The mathematical sphere is a model. It's not anything in reality. We often use models to make predictions about reality, but that...