So the frequency of a photon you measure is relative, but if you know the distance or and speed and angle you were traveling when you observed that photon, can't you just always work out what the actual energy change is that created that photon, in which case isn't the energy change of that object not actually relative, doesn't actually have to be a definite value in order for you to have measured it at the frequency and angle and speed you measured it at?

"but if you know the distance or and speed and angle you were traveling when you observed that photon"

Speed and angle relative to what?

"but if you know the distance or and speed and angle you were traveling when you observed that photon"

Speed and angle relative to what?

 

I suppose to the source.

I suppose to the source.

 

Which makes the result relative to the source.

Which makes the result relative to the source.

 

But that's the issue, because if you know all of the factors of the relativity, you would always be able to trace it back to the same energy change no matter how you relate to the position.

But that's the issue, because if you know all of the factors of the relativity, you would always be able to trace it back to the same energy change no matter how you relate to the position.

 

Yes, you can do a transform to see what the energy is in any other frame.