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Just wondering... if i have a photon moving in the z direction 4 momentum given by (0,0,1,1)

and I lorentz boost it in the z direction... would I get the same original 4 momentum (0,0,1,1) cuz i thought that boosting something at the speed of light means that it remains at the speed of light right?

in the case of the x direction (1,0,0,1) the lorentz boost in the x direction gives (cosh, -sinh, 0,1)... which isn't the original 4 momentum

could somebody kindly explain what exactly i'm getting wrong here?

Thank you!

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# Lorentz Boost of a photon

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