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Superman throws a light emitting object away from himself fast enough to notice a red-shift. The object passes through a region in which time runs more slowly. From Superman's perspective, does the red-shift change as the object slows or is the light's appearance unaffected?

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  • $\begingroup$ Is there a common thought on this topic in the theoretical physics community? $\endgroup$ – Brien Malone Nov 12 '11 at 5:38
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The object doesn't slow in this case, it speeds up. The redshift is increased. The clock-slowing-down factor is more traditionally called the gravitational potential, and where clocks are slow, this is close to a massive object. In the extreme limit that the light-emitting-object is approaching a black hole, time stops relative to Superman, so that Superman sees the object infinitely redshifted.

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  • $\begingroup$ Sorry to leave this hanging for ... gulp 3 years... I never received notification that this was answered! Weird. Oh well -- points for you. $\endgroup$ – Brien Malone Sep 18 '15 at 21:45

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