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One is called Bremsstrahlung radiation where high energy electrons are diverted from their paths by a positively charged atomic nucleus.
We have the "simple" fields predicted by the 1st of Maxwell's equations, otherwise known as The Divergence Theorem and then complex time-varying fields such as those associated with Maxwell's 4th equation (Ampere's circuital law) which predicts the radio waves Hertz became famous for and things like Bremsstrahlung.
To (maybe) better understand this, consider what would happen if we had an interacting, self-gravitating cloud of gas and dust that did not emit any photons (i.e. no Bremsstrahlung radiation, nothing but elastic collisions).
Bremsstrahlung lost is the most significant issue in this scheme.