# Speed of light in a given direction based on frame of reference [duplicate]

Possible Duplicate:
How is the speed of light constant in all directions for all observers?

Is the speed of light constant regardless of frame of reference? If not, why is it still measured as such, and if it is, why isn't it measured as being different in different directions?

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Possible duplicate/related? physics.stackexchange.com/q/49862/11053 –  Kyle Jan 23 '13 at 19:33
@Kyle No, because I'm asking just about the measured speed and its relation to relativity, while that question is dealing with the pulses used to measure that speed. –  Garan Jan 23 '13 at 19:57