Naively, one can attempt to consider the (impossible) light-speed inertial frame. From there you arrive at nonsense conclusions like 'the universe is flattened in the direction of travel' which must 'occur in 0 time' as the former implies '0 travel distance'.
Confusion arises with respect to polarization - I'm not familiar with the details but as I understand it a photon / electromagnetic wave is the solution one arrives at when considering a situation where changes in the electric and magnetic fields influence eachother, the interaction itself propagating as a result in an effective direction with some energy carried (frequency of the wave oscillations). The relation between E and B fields entirely determines the polarization nature of such waves, as I understand it.
Put simply - For any change to occur, time is required; EM waves such as photons require coupled, propagating changes in respective EM fields, which implies that this occurs over some distance. The reasoning being that to note changes in a given space, time must pass, and to note changes over a given time, space must change - governing this is the speed of light, a local ratio of temporal to spatial distances.
Given that a photon is, for lack of better terms, a chain reaction of events in the EM fields, why do we assume that:
- A photon will never decay?
- A photon does not 'experience' time generally?
This isn't to contest that a photon is (as far as is known) stable so much as to understand how times and distances 'work' for massless propagating entities, and the temporal / casual nature of such propagations.
If these aren't actually assumptions in use today, that hasn't been made very clear to me before. However if one assumes #2 to be true, it would necessitate #1 to be true (no time experienced = no internal changes), so I feel this needs clarification.