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Are relativistic effects physically real or just apparent due to limited speed of information? Does metal rod really contract in length or do we just "see" it that way due to limited speed of light?

Explain how do you reconcile the concept of physical reality with symmetry principle in special relativity?


marked as duplicate by sammy gerbil, rob Jan 15 '17 at 1:58

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  • $\begingroup$ they are physically real. $\endgroup$ – user121664 Jan 15 '17 at 0:32
  • $\begingroup$ OK- if that is so how can all inertial frames be equivalent? If two rods are moving relative to each other than each should be shorter than the other one? What kind or "reality" depends on the point of view? $\endgroup$ – user142073 Jan 15 '17 at 0:37
  • $\begingroup$ "What kind or "reality" depends on the point of view?": Ours $\endgroup$ – user126422 Jan 15 '17 at 0:55

Yes, an observer will deduce in his frame that the length of a moving rod (which has a length l in the rest frame of the rod) has shortened by a factor of 1/gamma (gamma=Lorentz factor). So in his frame it has a length 1/gamma.

This does not necessarily mean he sees it like that, arising from the practicalities of how we see objects moving at the speed of light (eg light emitted from further away takes longer to reach eyes, so a moving perpendicular line will appear curved). This is not an effect arising from relativity though.

  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. Participants in the chat are kindly reminded to be nice. $\endgroup$ – rob Jan 22 '17 at 22:28

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