There is a constant debate in Electromagnetism between the Charge-based views and Field-based views. I am of course over-simplifying the picture here, at least terminologically. But the main point is that you can talk about EM either from the point of view of; (i) objects that have mass, like electrons, protons, ions etc – I called them collectively charges or charge carriers, or (ii) entities that carry EM energy, like strength of electric and magnetic field, Poyinting vector etc – those are not associated with mass. Both views are often linked to some form of motion, or dynamics. For the world of objects people talk about moving charges, electric current, static charges etc. For the world of fields, people talk about EM waves, TE, TM and TEM, energy current, static field etc.
Often people talk about a mix of both views, and that’s where many paradoxes and contradictions happen. For example, there is an interesting ‘puzzle’ that has been posed to the world by Ivor Catt. It is sometimes called Catt’s question or Catt Anomaly.
Basically, the question is about: when a step in voltage is transmitted in a transmission line from a source to the end, according to the classical EM theory charge appears on both wires (+ on the leading wire, and – on the grounded wire): Where does this new charge come from?
Surprisingly, there has not been a convincing answer from anyone that would not violate one or another aspect of the classical EM theory.
Similar to this, there is a challenge posed by Malcolm Davidson, called Heaviside Challenge https://www.oliver-heaviside.com/ that hasn’t also been given a consistent response even though the challenge has been posed with a 5 thousand USD prize!
So it seems that there is a fundamental problem in reconciling the two worlds, in a consistent theory based on physical principles and laws, rather than mathematical abstractions.
However, there is a hope that with the way to understand and explain EM phenomena, especially in high-speed electronic circuits, is through the notion of a Heaviside signal and the principle of energy-current (Poyinting vector) that never ceases from travelling with the speed of light in the medium. In terms of energy current perfect dielectrics are perfect conductors of energy, whereas perfect charge conductors are perfect insulators for EM energy current.
So, while those who prefer the charge based view of the world may continue to talk about static and dynamic charges, those who see the world via energy current live in the world where there is no such a thing as static electric or magnetic field, because TEM signal can only exist in motion with a speed of light in the medium. Medium is characterised by its permittivity and permissibility and gives rise to two principal parameters – speed of light and characteristic impedance. The inherent necessity of the TEM signal to move is stipulated by Galileo/Newton’s principles of geometric proportionality, which effectively define the relations between any change of the field parameter in time with its change in space. Those two changes are linked fundamentally, hence we have the coefficient of proportionality delta_x/delta_t, also known as speed of light, which gives rise to causality between the propagation of energy or information and momenta of force acting on objects with mass.
Another consequence of the ever-moving energy current is its ability to be trapped in a segment of space, pretty much what we can have in a so called capacitor, and thus form an energized fragment of space, that gives rise to an object with mass, e.g. a charged particle such as an electron. So, this corollary of the first principle of energy current paves the way to the view of EM that is based on charged particles.