Newton: Inertia & the Laws of Motion


Reference: Disturbance Theory


Newton’s First Law states, “Every body continues in its state of rest, or of uniform motion in a right line, unless it is compelled to change that state by forces impressed upon it.”

In my opinion the right line is an approximation of the curvature of a circumference of near infinite radius. Therefore the curvature of the right line is negligibly small, but there is a curvature.

The normal problem with the perception of uniform motion is that we can give it any velocity by choosing an arbitrary inertial frame. We can “see” a particle moving at the speed of light by imagining an inertial frame that is moving at the speed of light in the opposite direction.

Any body that is naturally in uniform motion is actually rotating around some axis. It has a radial component that may be negligibly small because the distance of the body from its axis of rotation is infinitely large. But it is that radial component that must be referenced to get the correct idea of the tangential component, which we happen to see as uniform linear motion.

Newton’s first law is correct in a relative sense only because the uniform motion also occurs when the net force on the object is zero. Here we have forces acting on the object, but they balance themselves out.

When a body maintains its status quo of motion in the absence of force, it is said to have inertia. Newton attributed this property to matter only, because electromagnetic field as a substance was not yet discovered in his time.

Newton was very uneasy about ‘action at a distance’. He would have readily accepted the concept of the field because it gave a better explanation. Newton would have assigned the property of inertia to field as well, because field maintains its frequency in the absence of external influence.

The Newtonian body is actually made up of atoms. Atoms are made up of a field of rapidly increasing frequency. Electrons are like “eddies” in that field. The nucleus forms up at the center of an atom as a very condensed field, which contains the most mass.


Newton’s Second Law states, “The change of motion is proportional to the motive force impressed; and is made in the direction of the right line in which that force is impressed.”

Each particle in this universe seems to be moving under the influence of some force, whether by itself or as part of some body. The planets are not only spinning but they are also revolving around another object. Both of these forms are angular momentum. Such is the case with galaxies and, maybe, with cluster of galaxies and larger objects. The angular momentum not only pins an object to itself, but also pins it in relation to another object. It is an important component of inertia.

The simplest example of a motion would be circular, with a constant angular velocity. The tangential component of such a motion will have a uniform constant velocity. It would appear to move in a right line especially when the distance from the axis is very, very large. Its true motion can be comprehended only from the viewpoint of the axis around which it is rotating. Its “uniform motion” from any other origin will be fictitious.

So a plane flying in a right line with constant velocity has that linear motion as the resultant of many different motions. The real motion of the plane can only be comprehended, from an axis around which it is rotating at that instant. That axis gives it a certain angular velocity and radius from which the uniform motion may be assessed correctly.

All real motion requires acceleration and force. The linear momentum is the result of an angular momentum that has a very large radius. 

A more general relationship that defines force is the rate of change of momentum; or F = dp/dt, where F is force, p is momentum, and t is time. The general equation may be extended to field as follows:

Momentum, p = E/c = hf/c, where E is energy, ‘c’ is universal constant of space to time ratio, h is Planck’s constant, and f is frequency.

Force, F = dp/dt = (h/c) df/dt, where df/dt is the gradient of frequency.

A very high gradient of frequency exists on the surface of particles like electrons, protons and neutrons, that are like eddies or whirlpools in the field comprising the atom. This force is responsible for the gravitational attraction between particles.


Newton’s Third Law states, “To every action there is always opposed an equal reaction: or, the mutual actions of two bodies upon each other are always equal, and directed to contrary parts.”

The constant speed of light may be looked upon as due to the balance of two opposite forces. There is forward acceleration of the photon, which is checked by its internal inertia. If the inertia were not there, the speed of photon shall be limitless.

The Newton’s Laws of motion implicitly include inertia. The inertia of the nucleus of an atom is greater than the inertia of a photon escaping from the atom by many orders of magnitudes. This is the same ratio as the inertia of matter to the inertia of light.

The vector addition supported by Newton’s Laws of motion applies to a level of inertia corresponding to matter. It cannot add the negligible inertia of light to the inertia of matter, where the levels of inertia are far apart by many orders of magnitude. This vector addition is replaced by relativistic addition. This is the primary success of Lorentz transformation and Einstein’s special relativity.

The speed of light ‘c’ is basically a universal constant that  defines the relationship between space and time. But the “speed of light” is a poor reference point of all inertial frames. This is because light has a finite amount of inertia even when it is infinitesimal. A reference point of all inertial frames must have zero inertia. Light is a good approximation as long as it is being used as a reference point for inertial frames relating to matter and not to field.


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