Comments by "Dr Gamma D" (@DrDeuteron) on "The Experiment that Proved Einstein Was Wrong | Quantum Eraser" video.

  1. but that's not true. These experiments are performed in air, where the speed of light is 0.9997c
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  2. so you oversimplified the DCQE experiment (because it's too complicated to explain in a video that also covers Bell's Inequality/EPR) to the point that refuting acausal information is impossible. But the answer is no: information does not go backwards in time. What you showed is more like the Elitzur–Vaidman bomb-tester experiment, which is weird--the experiment that is.
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  3.  @eSKAone-  there are no reference frames at the speed of light, it's just meaningless to talk about it. Lasers in the lab move at 99.97%c in air because the index of refraction is (n-1) = 278e-6.
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  4.  @NeovanGoth  yes, I know how index of refraction works. Nevertheless, the information travels at the group velocity, which is less than c. If this were not the case, the photon could never change (since there is no delta t). If it beam splits, it slows down in the splitter, if the polarization rotates, it's slowing down in the ionosphere. The point is, you can't use the zero-time argument to explain the quantum behavior. (Quantum mechanics, quantum optics/photonics is inherently non-relativistic anyway: it uses a Hamiltonian, so it's no surprise you get spooky action at a distance, as v < c is not in the theory...QED, on the other hand, uses a Lagrangian and is a fully relativistic theory...which leads to weird things like the spin-statistics theorem).
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  5.  @christophermullins7163  c is c, duh. But people who work with EM waves in media say "the speed of light" to refer to the speed in the medium, which doesn't mean anything because it's frequency dependent, that is: most media are dispersive. And I've worked in gamma, X, near UV, vis., IR, mm, and microwave: W, V, "G", Ka, K, Ku, X, C, L, P...no S, bands, and VHF..that I can remember)...and that's just how it's done.
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  6.  @nothingnothing1799  wait, nothing can go faster than c/n in a medium? That does make sense.
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  7.  @owfan4134  ironic since wheeler Feynman absorber theory relies on the linearity of solutions to maxwells eqs.
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  8. Thorne
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  9.  @acoral1035  also: It's Wheeler (John Archibald, Feynman's advisor). The book, Gravitation, was a huge black tome that was a must in Kip's class, and it was just called "MTW". This was around 1990, and he had been talking about detecting gravitational waves since the 70s. It seemed impossible, but they pulled it off...only took 25 more years. A well earned Nobel Prize. One of the students in the class also got one, for Sag A*.
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  10. but we're not. QM always describes experiment.
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  11.  @vejet  That delayed absorption view of propagation through a media is silly. Index of refraction is caused by permeability (epsilon), if differs from the vacuum value. the speed of light ~ 1/sqrt(epsilon), so, the EM waves moves slower. A single photon is much larger than an atom, so it's interacting with a background cloud of bound electrons from many atoms.
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  12.  @michaeljorgensen790  the Lorentz Factor for light in an index of refraction of 1 + x with x<<1 is 1/sqrt(2x) --> 43 for air.
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  13.  @josephbrownbrown8212  your post reads as if it was written by a somewhat lazy native speaker.
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  14. except photons in air travel slower than light, and have a normal at rest reference frame, like the rest of us.
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