Freedom of Science

In physics anything which is not a physical quantity is metaphysics. There is no exception to this rule. Example: “Newton’s laws” is not a physical quantity therefore “Newton’s laws” is metaphysics and does not belong to scientific physics. Laws, principles, axioms, definitions, conjectures and similar philosophical stuff are independent of scientific physics. If we define physics as the science that studies physical quantities then we must accept that philosophical stuff belongs to metaphysics and not to physics. A physical quantity is defined as

This definition of physical quantity is free of metaphysics. If physics is defined as the science that studies physical quantities and physical quantity includes nothing but a number and a unit, then, we must conclude that anything which is not a physical quantity does not belong to scientific physics. We can easily define a scholastic type of physics or metaphysics by defining physical quantity as

This metaphysical physics would allow deep philosophical discussions of laws, principles and conjectures of all kinds but will be unable to make predictions because nature recognizes only true physical quantities and ignores the rest. Metaphysical physics is a lot of fun but it is no different than pre-Newtonian Peripatetic philosophy. As is well-known Peripatetic philosophers endlessly discussed laws and principles of their own definition and published long commentary on them. Galileo noticed the corruption of physics and eliminated the metaphysical part by making geometry the language of physics. In the 18th and 19th centuries great scientists developed the concept of physical quantity and made physics a rigorous science based on quantities tied to a consistent system of units. There is no room in the quantitative scientific physics for qualitative philosophy expressed as authoritative laws, principles, conjectures and branded equations. Therefore, a set of rules and definitions and principles called “Newton’s laws” is not a part of the science of physics. Newton’s laws can be a nice topic to discuss in a scholastic discussion group but not in physics.

Physicists may use such philosophical arguments as heuristics and pedagogy the way Einstein did but metaphysical elements will always exist independent of physical quantities. This means that the authority of physics comes solely from physical quantities and never from heuristics and metaphysics. No metaphysical law can be offered as an authority over a physical quantity. A scientific physicist works strictly with physical quantities.

So, to say that “Newton’s laws predict planetary orbits” as one hears all too often, is to assert Newton’s authority over physical quantities. “Newton’s laws” is not a physical quantity. Doing physics by invoking “Newton’s laws” reduces physics to metaphysics. No orbit ever heard of “Newton’s laws.” All that orbit knows is its radius and period. But if you say “Newton’s force predicts orbits” that would be a scientific statement because Newton’s force F is a legal physical quantity. Do you see how the point of view changes from a scholastic discussion on Newton’s laws to a scientific discussion about a physical quantity? It is possible to discuss scientifically if force predicts orbits but it’s not possible to discuss orbits with “Newton’s laws” because “Newton’s laws” is not a physical quantity.

This distinction is usually lost on students who are attracted to physics after reading science-fictional philosophy the media associates with physics. Beware that if it is not a physical quantity it is not physics. It is metaphysics. No exceptions.

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