Paul Colby's latest activity
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Paul Colby reacted to JimWhoKnew's post in the thread Graduate Gravitational wave propagation in GR - follow up with
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Metrics are symmetrical. TT gauge can only be obtained outside the sources. The 8 conditions are$$\partial^\mu h_{\mu\nu} =0 \quad... -
Paul Colby replied to the thread Graduate Gravitational wave propagation in GR - follow up.I don’t follow your question. [deleted synchronous gauge] -
Paul Colby replied to the thread Graduate Gravitational wave propagation in GR - follow up.As I recall transverse refers to ##\partial^\mu h_{\mu\nu} =0## which is the case. EM waves are transverse in that E and H are... -
Paul Colby replied to the thread Insights Remote Operated Gate Control System.There should be one (and only one) def per state. onStarting, onOpen, onClosed, onOpening, and, onClosing. Anyway, a working solution is... -
Paul Colby replied to the thread Insights Remote Operated Gate Control System.Cool project. State machines can be very effective. I find the design pattern used here kinda ugly. For certain, it works, but an... -
Paul Colby replied to the thread Graduate Gravitational wave propagation in GR - follow up.If I recall correctly, a plane wave in the TT gauge propagating along z is, $$ h_{\mu\nu} = H_+ f(t-z) + H_\times g(t-z) $$ where ##f##... -
Paul Colby replied to the thread Graduate Gravitational wave propagation in GR - follow up.At this point I find it instructive to consider some numbers. A round trip time for light in a 4km long interferometer is, $$... -
Paul Colby replied to the thread Spatial Perturbative Hamiltonians In Systems of Identical Particles.The spin states are completely degenerate since your Hamiltonian doesn't depend on spin. You've chosen an orthogonal set of spin states... -
Paul Colby replied to the thread Graduate Gravitational wave propagation in GR - follow up.I mean proper distance changes with ##s##, the proper time. These are frame independent quantities. In the TT coordinates, ##s=t##... -
Paul Colby replied to the thread Graduate Gravitational wave propagation in GR - follow up.Yes. The ##\Gamma^\mu_{\nu\alpha}## terms in the geodesic equation only sprout space components in the TT gauge. Basically... -
Paul Colby replied to the thread Graduate Gravitational wave propagation in GR - follow up.In the TT gauge (coordinates), the metric stain, ##h_{ab}##, only has spatial components, ##h_{xx}, h_{xy},\cdots##, are non-zero and... -
Paul Colby reacted to Vincf's post in the thread Undergrad Velocity of a free particle using Landau's approach with
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Upon further reflection, I think that my previous answer is correct except in some particular case. Let us consider the case where : $$... -
Paul Colby reacted to Dale's post in the thread Graduate Horizontal component of the electric field of an infinite uniformly charged plane with
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It actually isn’t different if you are close to the center of one of the plates. And it is a good example to show that the “vertical”... -
Paul Colby reacted to A.T.'s post in the thread Graduate Horizontal component of the electric field of an infinite uniformly charged plane with
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I think it similar to the proof that pi=4 in the video below at 1:39. The explanation at 15:09 points out the fallacy @PeroK mentions above.