The question: If a photon picks up energy from an electron in an interaction is it still the same photon?


Remarkably, there is no way to tell, even theoretically.

In a typical "Feynman Diagram", the method used to make that computation for electron-photon scattering, the photon is first absorbed on the electron and then re-emitted. Is it the same photon? Nobody has proposed any test that could determine that.

But there is a second Feynman diagram in which the photon is emitted before it is absorbed. So in that diagram, there is (briefly) two photons present. Then the first one is absorbed. In this case, it appears that the photons are different.

Now the really remarkable part. Both of those two processes take place with every scattering. In other words, the photon is the same photon, and a different photon, simultaneously. Quantum weirdness on display.

That's why I say that in principle there is no answer.

Shades of Schrodinger's cat, when the cat is both alive and dead at the same time. But for electron photon scattering, if you don't include both diagrams simultaneously, you get results that don't agree with experiment. If you include them both, your computations are verified by the measurements.

 

Sunlight reduces clotting but centralized healthcare keeps writting Rx's for meds and not sunlight. Anyone on a blood thinner is solar deficient = decentralized medicine axiom. In 15 years I have never seen a person on a blood thinner with a Vitamin D above 60 ng/dl. https://pubmed.ncbi.nlm.nih.gov/19335448/