lmm comments on Stupid Questions Thread - January 2014 - Less Wrong

10 Post author: RomeoStevens 13 January 2014 02:31AM

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Comment author: lmm 13 January 2014 11:05:52PM *  4 points [-]

Does this mean that a photon emitted at location A at t0 is absorbed at location B at t0, such that it's at two places at once?

In the photon's own subjective experience? Yes. (Not that that's possible, so this statement might not make sense). But as another commenter said, certainly the limit of this statement is true: as your speed moving from point A to point B approaches the speed of light, the subjective time you experience between the time when you're at A and the time when you're at B approaches 0. And the distance does indeed shrink, due to the Lorentz length contraction.

In what sense does the photon 'travel' then?

It travels in the sense that an external observer observes it in different places at different times. For a subjective observer on the photon... I don't know. No time passes, and the universe shrinks to a flat plane. Maybe the takeaway here is just that observers can't reach the speed of light.