Newton's Third Law or Law of Action and Reaction

When a force acts upon a body it produces an equal force but in the opposite direction. This law has more technical or instrumental nature.

Cover of the Physics and Global Dynamics book. Cassiopeia A supernova remnant.



Author: José Tiberius

Technical assistant:
Susan Sedge, Physics PhD from QMUL  



2.c) Newton’s Third Law or Law of Action and Reaction

According to Wikipedia, Newton’s Third Law explains that, for each force that acts upon a body, there is equal force but in opposite sense upon the body that produced the force.

If Newton’s Second Law is the Fundamental Law of Dynamics because it establishes concept of force as magnitude that associates mass with movement, the Law of Action and Reaction has more technical or instrumental nature.

Newton's Apple
Still life of fruits with dark background.

In fact, Newton’s Third Law, or principle of action and reaction, reminds of Luca Pacioli’s double-entry accounting system outlined in his book, Tractatus particularis de computis et scripturis (1494), and he is the grandfather of modern accounting. Both techniques use pairs of equal amounts to facilitate numerical calculation, which is not particularly complex, but rather extensive.

Moreover, the double-entry accounting system and Newton’s Third Law have the same deficiencies in that they subordinate concept clarity to practical advantages.

To briefly mention a few, double-entry system ends up placing concepts, in the assets’ side of the balance sheet of companies, that are very different, such as buildings, computer programs, patents, or cash. Another odd technique is to end up entering building of both a factory and a sports center as investments in accounting books.

A figurative example of Newton's Third Law would be to say that if a person gives an apple to another one, the latter returns a negative apple and the total sum remains unchanged and, in the end, the number of apples each person has inevitably corresponds to observable reality.

Therefore, we cannot argue that Law of Action and Reaction is not true or useful. Nonetheless, we still have never seen nor have been able to imagine a negative apple. Negative objects do not exist in the world. Likewise, we can say negative forces do not exist, except those that have conventional or purely mathematical nature. However, opposite forces do exist because the force is a vector magnitude.

This instrumental characteristic of forces of action and reaction in Newton's Third Law presents two problems that might end being important:

  • By becoming so transfixed on such elementary concepts, the human brain can eventually end up thinking about the physical existence of pairs of forces of action and reaction that this law refers to. Moreover, by extension it is possible to end up thinking about the existence of negative energies and even negative masses. Especially, after scientists talking about reverse time all the time.

    Not to mention if the orthodox doctrine also defines negatively potential energy and it calls the positron and certain types of mass antimatter.

  • In models with numerous forces at play, forces that are real, or imply physical mechanisms, and those that are conventional are not always very well distinguished.

We cannot forget that magnitudes such as velocity, force, or energy are merely properties of the reticular structure of matter –gravitational, kinetic, or Global Aether– in its different phases or physical states. That is, real forces mean a transfer of energy or modification of the elastic properties of Global Aether.

Another big problem with Newton's Third Law, or Law of Action and Reaction, is the need to create fictitious forces regardless of the purely mathematical forces previously mentioned.

Newton was aware of these problems but he recognized that science was not advanced enough to delve into physics concepts that, according to him, were still a mystery. For instance, Newton pointed out that he did not like the distant forces from his Law of Universal Gravitation. This idea is a clear precedent for the principle of Mach and the existence of an aether.

Reaction forces are elastic reactions of materials, either directly or through a chord, as the centripetal force in the case of a stone turning in the David wave.
Now, the centrifuge is a consequence of the inertia of a body to follow its trajectory (Newton's 1st Law). It is a fictitious force because it is unknown the reaction force's origin.

In the Global Physics model, the body inertia comes from the action and reaction at the level of the nucleons produced by the elasticity of space-time or, rather, the Global Aether. We are not too fond of the term space-time because nobody knows what it is –it might be dark e-t.

Furthermore, finding the reaction force to the gravity force is difficult. If the action force is the attraction of the Earth by the Sun, the reaction force is not the attraction of the Sun by the Earth. We could talk about the force of attraction of the Earth by the supermassive black ball at the center of the Milky Way, with thousands of light years of time lag and very distant points of application of the forces involved.

Newton's Third Law represents something similar to the Principle of Global Conservation, that energy does not create or vanish, but rather changes from one form to another.

Let us see a simplified example, the Earth, and an object. In addition, we consider only the movement of the little object. Gravity force comes not from the Earth but its gravitational field, and the reaction force would be against that field.

  • Gravity force increases the kinetic energy of the object.

  • The increase in kinetic energy comes from a decrease of the sum of the gravitational field of the Earth and the object. There will be a change in the gravitational fields’ spatial configuration when an object gets closer to the Earth. In other words, the closer the Earth and the object are, the smaller the sum of the energy of their gravitational fields is.

    Mechanical energy
    Graphs on kinetic energy and gravity by nonlinear increase of the area under the curves.

    This effect is similar to the bond energy in chemistry. An intuitive example can be the volume under the sheets of two balls in the bed, when they are together it will be minimal. Note that both the binding energy of the atomic nuclei and the gravitational potential energy have a negative sign mathematically.

In any case, we are grateful to Newton for his Law of Action and Reaction and his position on finding explanations of physical nature. Also, for using common sense in a world where almost no one knows nor gives answers; and the rest, either they stretch out time, creates new and vibrant dimensions, they feed off negative apples or come and go to other worlds or parallel universes.

From a scientific point of view, there cannot be an exchange between what is real or physical and what is imaginary or abstract, despite how much one can end up confusing concepts. Likewise, the real world does not end when a person dies. Nor a person's spiritual world ends, but that is more of love philosophy than Physics science.



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