Tuesday, May 27, 2014

Sklar on Newton's Force

Here is an excellent quote I found in the library last week:

From Philosophy and the Foundations of Dynamics by Lawrence Sklar (2013)

For Cartesians Newton’s force is, of course, a terrible Aristotelian throwback. It is an “occult quality” that objects possess in and of their nature. For example, all objects, merely by virtue of having their inertial mass, also have what would now be called “active gravitational charge.” They possess the property of affecting the motion of other objects by exerting a gravitational force upon them. (p. 93)
The invocation of the notion of force in the Newtonian sense immediately leads to controversy over what such an element of the world ought to be taken to be. Is force some primitive quality of things? How do we grasp its nature in the world? What is the status of the term used to refer to? Here we see the continuation of a long-ongoing puzzle about fundamental theories. How do we interpret those concepts of the theory that are introduced in its explanatory apparatus in a manner that is internal to the theory, not imported into it from pre-existing language. The concepts relating to the position of things and their variation in time seemed to most of the physicists to be unexceptionable – at least until their “absoluteness” is claimed! But how do we grasp the meaning of “force” as used in Newtonian dynamics, where it has ceased to be merely some measure of a quantity of motion? (p. 115)

The question Sklar poses at the end has never really been answered, at least not in mainstream established physics. In physics force is a verb meaning push or pull. So we always have to ask ourselves what physical entity is doing the pushing or the pulling? What is mediating the push and pull between atoms? We can describe push or pull in an infinite number of ways and this is obvious with all the descriptive forces coming out of the physicists since Newton, e.g. nuclear force, Lorentz force, Van Der Waals force, etc. But we always come back to the fundamental question: WHAT is doing the pushing or the pulling in between. What object is mediating gravitational force between atoms? Electromagnetic force??? Without a hypothesized object doing the pushing or the pulling it is impossible to explain force.  And so the forces are fittingly described as occult, and so can particle physics, quantum mechanics, physical cosmology, relativity, etc. be described as occult.  They do not understand what they are describing.


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