(I tried, but the wikipedia chapter is too complicated for me => trying to simplify here)
> ...it's momentum and energy.
Therefore, if the photon does not have a mass but is still able to have an effect against the target body it impacts with, then the photon must lose energy, right?
[puah - for some reason I cannot reply to the my post's - typothrowaway's - reply...]
I can imagine. That stuff on the wiki is not even in every physics bachelor. It's definitely not for a general audience, but I thought it might help a little :)
> Therefore, if the photon does not have a mass but is still able to have an effect against the target body it impacts with, then the photon must lose energy, right?
Yes, or gain it if it slows down the object, if the object is traveling towards the light.
Or the internal energy of the object is changed. This happens when a photon is absorbed.