The forces of inertia and gravitation

Newton, whose name we know from our school-days, put into scientific practice three new entities that make up his famous laws: gravitational force, inertial force and mass possessing inertial and gravitational properties. Before, mass was considered a measure of the amount of substance. These new entities were introduced Ad hoc (from LatinAd hoc - to this, for this case, for this purpose). Thus, gravitation forces were introduced to explain the falling of bodies on Earth, and inertial forces explained the bodies' resistance to change of state of rest. In particular, inertial forces explained why the cosmic bodies, rotating in ellipses around each other, do not fall on one another due to the force of gravitation.

An independent confirmation of the existence of each of the introduced entities became the immediate task of science. The equivalence principle became an essential step in this direction. It was discovered in the course of an experiment 320 years ago. Equality of inertial mass and gravitational mass to each other was and is the most significant evidence of the real existence of all of the above-mentioned entities in the history of physics.

At the time of Newton, the mathematical approach dominated in science. According to this approach, the main task of science is to formulate a mathematical equation that describes the observed phenomena. The questions "Why is the centrifugal force equal to the centripetal force?" and "Why is the inertial mass equal to gravitational mass?" did not even arise. The equivalence principle was declared and became practically the fifth law of Newton. It should be noted that the answer could not be found in Newton's time. The facts were found afterwards which can help us to answer these questions, namely:

1. all material bodies are composed of identical charged particles (electrons, protons and neutrons), and their number in each body is directly proportional to body weight;
2. neutrons are made of positive and negative charges;
3. a new science - electrodynamics - appeared which introduced new forces and new laws into physics.

Electrostatic forces (Coulomb forces) and electrodynamic forces (Lorentz forces) became new forces. In the framework of electrodynamics it was proved that the charge moving with acceleration causes the emerging of force operating on this charge (force which is equal in value to the force that caused the charge motion with acceleration, and which is in direct opposition to this force in direction). This phenomenon does not depend on the type of force that caused the charge motion with acceleration. Coulomb force, gravitational force and inertial force can be such a force, but the acceleration may be both centrifugal and linear. 

How, taking into account electrodynamics, can experiments be explained in which centrifugal force is equal to centripetal force? (for example, the planetary movement)

The charges which make up the material bodies are moving with acceleration that leads to the emergence of self-induction which, as we have said, is operating on the charge with the force equal in value and opposite in direction of operation of the centripetal force. Since it doesn't matter for this force what caused such a motion - whether the gravitational force (the force of attraction of the planets), or centrifugal force MV²/R - this force will manifest itself with equal facility. The equivalence principle is satisfied in this case by definition of the phenomenon (force) of self-induction. Thus, it appears that inertial and gravitational and electrical properties of a body are all determined by charge, not mass. The original entity is a charge, not mass. We found an answer to the question of why the centrifugal force is equal to the centripetal force without using the concept of mass, and it is proof of that mass does not exist as an independent entity.

Is it possible to say on the basis of this conclusion that Newton made a mistake in the process of the discovery of his laws? Certainly not. Newton's laws have an enormous evidence base and widespread use. We have considered a special case in which an explanation of the inertial and gravitational forces is possible without the use of mass, and we assume that in other cases of the manifestation of the equivalence principle the same system works, and that the gravitational force can be explained on the basis of electrodynamics.

Our explanation of the equivalence principle is an illustration of Bacon's widely known utterance: "A new theory is a child of time, not of authority."