This is part of a new theory about the nature of space, electric charges and electric fields. In classical physics, we tend to perform mathematical operations without asking too many questions about the underlying processes of nature which we are trying to understand. Thus we calculate the electric field intensity at a point as the vector sum of the fields of the individual electric charges without asking questions about the nature of the field. In another section of the same book we might find we are adding scalar fields of electric potential and then differentiating the result to find the electric field. Only when we discover that every electric field has an energy density do we need to enquire more deeply what is going on.
Take a very simple situation where we have two single charges a very long way apart. Each has an electric field surrounding it. That electric field has an energy density at every point in space. The total energy content of its electric field depends on the physical size of the charge. You might like to think the charge has no size in which case you will say that the energy content is infinity. I, wanting to avoid such a horrible concept prefer to think of the charge as having a surface of finite radius which gives the total energy content a finite value. Conventional wisdom has it that as we bring the two charges together, their electric fields add by vector addition giving a combined electric field. The combined electric field is said to be real while the individual electric fields only have separate existence in a mathematical sense. This interpretation allows us to calculate a total energy content of the combined electric field which is different from the sum of the energy contents of the two individual charges. The changes in the energy content of this combined electric field as the distance between the charges varies is said to store the potential energy which the two charges posses by virtue of their distance from each other.
The principle of superimposition takes the opposite view that the two electric fields have a separate existence enabling their energy content to remain unchanged as the two charges are brought together,
The principle of superimposition provides a simple answer to two of the most difficult questions we can pose in physics. How do electric charges exert forces on each other? How are magnetic fields generated. The principle of superimposition asserts that a charge and its electric field are two aspects of one and the same thing. That a charge is a polarisation of space towards a point which terminates in a surface, possibly spherical, surrounding a point at the centre of the charge. The surface is a raw edge of the polarisation of space and as such is not really distinct from that electric field. Thus every electron and quark has an extended presence throughout space. Thus they give to space a local property which results on an element of a charge at that point experiencing a force. A charge feels a force from each of the electric fields present at its location and these forces naturally sum by the process of vector addition. We can account for magnetic fields in terms of the relative movement of electric fields through each other. As an electric current flows through a wire, the electric fields of the electrons composing the current move with it through the background of the electric fields of the other charges composing the structure of the wire.
I would say that the existence of magnetic fields is sufficient proof of the principle of superimposition.
We are then left bereft of an exaltation for the storage of potential energy which puts us back in the position to be found in Newtonian mechanics where the potential energy of a book on a shelf is a purely abstract idea depending on the geometry of the situation. But that is something I can cope with in the light of the fact that the principle of superimposition allows us to understand such mysteries as the action of electric force at a distance, the generation of magnetic fields, the null result of the Michelson-Morley experiment, the increase in mass and the consequent slowing of clocks at high velocity, the storage of kinetic energy, Newtons laws of motion and the existence of gravitational forces. Not a bad trade in.
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© Copyright Bruce Harvey 1997.