This question will be in some way complicated for different reasons - I am no physicist, I know about things like wave-particle duality, that the tranversal wave motion comes from change in electric field strength and magnetic flux density but I have no good imagination about all of it. So I will try to add further question that I probably will need answers to to get a sufficient answer to the title question.
What means observing in sense of wave-particle duality. When does a quant feel observed.
Why does a quant want to do a transversal motion by still maintaining the actual motion direction (ignoring gravitation which should effect the photon/quant because of its kinetic energy) - and how do they do it without loosing kinetic energy.
The answer at some point will probably be you consider particle properties at one point and wave properties at another point. Or you think about a model created to represent a certain property and draw conclusions from this model exceeding the actual limitations such a model has.
So I would like to understand when is light a wave and when it is a particle and if it is always both then when does it have certain properties, when does it loose them and when does it gain different ones instead. (Could it loose wave and particle properties - and what would be left of it in that case?)