Comments by "Dr Gamma D" (@DrDeuteron) on "Special Relativity Part 2: Time Dilation and the Twin Paradox" video.

  1. 0:40 ..... "the faster you move relative to the speed of light"....is deeply confusing. You can't move relative to the speed of light. No matter your motion, the speed of light is always "c" in all directions.
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  2. if you don't understand the freestanding twin paradox, introducing gravity into the mix is not going to make anything clearer, as you are comparing two non-inertial paths in curved spacetime. That problem requires integrating (1/g_tt) from the metric over the paths, et voila, the traveling twin is younger. See how much that didn't help?
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  3. EK's description is fine, in that it shows the change in space clock's bias back on Earth is consistent with an interpretation of gravity being indistinguishable from acceleration, with gravitational time dilation being applied. Technically correct, but not very helpful, unless you want to understand why gravitational time dilation is not cause by the local strength of the field, but rather the magnitude of the gravitational potential...which is non-local.
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