Fundamental question

Main Question or Discussion Point

Why must the 4-momentum for photons $$p^\mu =(\frac{h\nu}{c},\frac{h\nu}{c} \textbf{e})$$ transform as a 4-vector in Special Relativity?

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Dale
Mentor
I don't understand the question. The four-momentum transforms as a four-vector for all particles, not just photons.

CompuChip
Homework Helper
And if you apply an arbitrary Lorentz transformation, you can easily check that it does.
You can even derive it (Let $p^\mu = (p^0, \vec{p})$, apply a Lorentz transformation and you will see what p0 should be).