All physical theory contains, either implicitly or explicitly, metaphysical components. No theory that concerns itself with the physical world--its forms, properties, interactions, or changes--can exist without including, on a fundamental but often tacit level, one or more purely metaphysical assumptions. In the contemporary world physics is often thought to be the hardest of the 'hard' sciences, which is another way of saying that physics is that discipline most rigorously concerned with understanding the physical truths of the universe. This, along with the consistent validation of physical truths in their applied form ("technology"), easily leads to the conception that physics has some particularly authoritative claim to insight concerning the ontology of the universe.

Nevertheless, a close examination of any physical theory, no matter how "proven" or "tested" will yield various underlying assumptions that can only be described as metaphysical. "Gravity"1 is a perfect example: ask any physicist if gravity exists, and the answer will be affirmative; ask what gravity is, and suddenly the responses become much stranger. Some might relate that gravity is an inherent property of mass, a "field" with attractive properties whose intensity decreases in exact proportion to the square of the distance from the center of the object of mass; others might mention space-time and the General Theory of Relativity and how mass distorts space-time to create something that looks like a "force". When pressed, however, it is mildly shocking to discover that, although the actual existence of gravity is entirely unquestioned, its particular ontology is quite mysterious. We don't really know what gravity is--in fact, Einstein showed that gravitational frames and accelerated frames can be treated identically (the math is the same in both cases).

Gravity is an old theory created as an explanation for otherwise unexplained phenomena (for example the observation that if one drops an object, it will always fall towards the Earth and not into the sky or parallel to the ground). We assume that something is happening in the universe to create these peculiar events, and we call it "gravity". Unfortunately, the creation of the term in conjunction with its subsequent widespread usage has resulted in the popular reification of gravity--it has been promoted from a concept to an actually existing force in the universe.

In general it would seem that in order to retain explanatory power a concept must have an ontological status that is more fundamental than the phenomena it explains. This is true not necessarily because of any logical rules, but because of the particular constitution of those that require explanation: namely, humans. The argument may be something like: "because it is obvious that objects actually fall towards the Earth, gravity too, must actually exist, because isn't that what causes the objects to fall towards the Earth? And besides, if gravity did not exist, then what would explain this phenomenon?". The incompleteness of the logic is glaring, but it can slide by unnoticed due to the unquestioning acceptance of the existence of "gravity". When examined critically, the theory of gravity remains metaphysical--its status cannot exceed that of an explanatory concept--one that can be more or less useful, to be sure, but a concept nonetheless.

The answer to the question "...isn't that what causes the objects to fall towards the Earth?" is negative. That objects fall towards the Earth is an empirical observation; the theory of gravity began as an attempt to provide an explanation of why this is so. Unfortunately, to have the concept of gravity does not necessarily result in the fact of gravity; rather, it placates those people who ask the question "Why do objects fall towards the Earth?" by posing as a valid, ontological "reason" for the observed events. Yet we still do not know what gravity is, only that in order to explain certain phenomena, it is valuable to posit something like what we know of now as "gravity".

Once the concept of gravity exists, it becomes possible to test its applicability in various ways, and through a careful process, the idea can be refined. New observations are made, which are subsequently compared with and related to older observations, and depending upon the specifics, the idea of gravity is modified to fit the new observations (for example that massless particles are affected by the 'attractive' properties that were thought only to apply to other bodies of mass).

It is often assumed (by physicists and philosophers alike) that physics poses only "What?" and "How?" questions, and in fact physics, abstracted from its existence as a human creation, does relate to physical truths in this manner. But physics as a discipline cannot be completely abstracted in this way, and when placed in its context as a human discipline, the fundamental motive for physical theory is seen to arise not from "What?" or "How?" but from the question "Why?".

To continually search for answers to this most difficult of queries inevitably leads beyond the conservative boundaries of physics and into the speculative realm of metaphysics, which also asks "Why?" In fact, metaphysics can be seen as an attempt to create a framework in which the question "Why?" can be answered directly, through the establishment of some sort of 'ultimate' upon which all explanation can and must finally rest. Still, as a general rule, an adequate metaphysical scheme must be able to take into account what we know about reality through physics; if it does not, then the scheme is inadequate and must be rejected or revised.

Whitehead knew this, and when he brought his metaphysics into clear formulation in the late 1920's, he made a remarkable effort to include what he knew from the developing field of physics. Between then and now, however, such significant advances in physics have taken place that it seems that Whitehead has been left entirely in the subatomic dust. In particular significant advances have occurred in the highly non-intuitive and extremely complex field of quantum mechanics--one of the most metaphysical realms in all of modern science and therefore one quite congenially related to Whitehead's own temperament.

On to Quantum Mechanics.

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