The thing is, can you definitely tell me they have annihiliated and then produced two entirely new photons, or have they just interacted, altering some of their characteristics? Given these characteristics are all you can know about photons, it doesn't matter which mechanism you think is true, the outcome is the same
How do you know that by interacting, the originally photons have not changed into new photons?
You don't, they are the same particle type and you can only define photons by their particle type, polarisation and momentum. Since the particle type doesn't change you have no method of differentiating between new photons and altered photons.
However, you might gain some insight into it by considering possible Feynman scattering. By conservation of spin I don't think you can have two photons combining into a single photon. Therefore lowest order scattering is photons interacting with one another. You can however get a infinitely many more complex fermion loops, where the photons turn into particle/antiparticle pairs, then back into new photons. In that case the photons were destroyed, then converted back.
It would seem we're both right, just it depends on the coupling force of electromagnetism Your scatterings are O(e[sup]2[/sup), mine is O(1).
Just to see who would like a picture of what for the society, not deciding on a specific picture, after a short dispute about whether we should have Feynman or Einstein.
Don't you think that's a bit of a strange comment for voting AGAINST Einstein???
Well Einstein was a good physicist however his rejection of quantum theory in spite of the evidence means that I see Feynman as a better physicist. Plus Feynman has really simplified our understanding of the physical world.