Quantum Mechanics. Quantum mechanics is the other great revolution in contemporary physics. Classical physicists would have admitted that the existence of ordinary material objects is a phenomenon that still needed an explanation, and as it turns out, that explanation came with the quantum revolution. Not only does quantum mechanics describe the electromagnetic forces responsible for the structure of all ordinary objects down to molecules and atoms, but the mathematics that is now used (in a gauge field theory called "quantum electrodynamics") is the model for explaining even the short-range forces (the strong and the weak forces) which responsible for the nucleus and deeper structure of material objects. The issues involved in explaining the truth of quantum mechanics is taken up in this chapter, and the two short-range forces, along with the basic particles of physics, will be explained in the next. The challenge posed by quantum mechanics and what is at stake in explaining its truth ontologically are discussed in the first section, and the rest of the chapter suggests one way, at least, in which its truth can be explained by spatiomaterialism. But at the outset, it should be noticed that spatiomaterialism already provides an explanation of how those forces are related to gravitation.

One of the greatest current mysteries of contemporary physics concerns the relationship between the force of gravity and the other three basic forces of nature. The problem is that the electromagnetic force and the two short range forces are explained by the exchange of a distinctive kind of particle (the gauge boson, such as the photon, in the case of electromagnetism), and the general theory of relativity does not lend itself to representation as a gauge field theory. The most promising way to represent gravitation as the exchange of such gauge bosons (called “gravitons” in the case of gravitation) would incorporate all four basic forces and the objects on which they act. But this so-called “superstring theory” requires the postulation of ten or more dimensions to space, and it seems to be completely immune from possible empirical falsification. There is nothing to recommend it but the mathematical uniformity in the representation of all four basic forces of nature, and as we have seen exclusive reliance on mathematics does not necessarily lead to the best explanation. .

Spatiomaterialism offers a solution to this problem, if quantum electrodynamics and the two short range forces are explained as interactions mediated by the inherent motion in space (that is, space as the "ether"), as I have been assuming, because this ontological explanation of relativity theory would also explain how the other three forces are related to gravitation. Gravitation is not a gauge theory, because the gravitational force acts on the inherent motion itself, that is, on space, not on bits of matter directly. It is by changing the “medium” (or "ether" as a condition of space) in which gauge particles are exchanged that gravitation accelerates bits of matter. It is not necessary for centers of matter accumulation to exchange gravitons with individual bits of matter in the region to accelerate them.

What makes the problem of relating gravitation and the other forces seem so intractable is the assumption that it requires the discovery of a law of nature from which Einstein’s general theory of relativity as well as the gauge forces can all be derived. The discovery of a basic law covering all the basic kinds of interactions among bits of matter has long been the so-called “holy grail” of physics, and that is the assumption that has led to attempts to formulate a gauge theory of gravitation. It seemed that such a basic law of physics could be discovered only if gravitation could be represented mathematically in the same way as the other forces. That is the goal of superstring theory.

Spatiomaterialism would solve this problem ontologically, rather than mathematically. The solution does not require the discovery of a new law of nature from which all the other laws follow, but only an ontological explanation of the truth of the laws that have already been discovered, for that reveals how gravitation is related to the other three forces. We have seen how the truth of general relativity can be explained ontologically, and thus, if spatiomaterialism can explain the truth of the other basic forces of nature in terms of the inherent motion in space, there is an ontological explanation of the relationship between the two kinds of forces. It is the recognition of the inherent motion (or "ether") as an aspect of the essential nature of space that makes this possible. By contrast, the gauge field theories are, in effect, the attempt to represent space as nothing but the forces by which particles interact.

If the explanation is ontological, what makes the problem of reconciling gravitation and the other forces of nature seem so intractable is, once again, the empirical method of physics, that is, the method of inferring to the best efficient-cause explanations of what happens in nature (and letting ontology be determined by realism about its theories). It was inevitable that physics would eventually find itself in this predicament, because physics first became a science by taking advantage of the power of mathematics to describe regularities about change. By insisting on mathematical theories that make surprising, quantitatively precise predictions of measurements, physics was able to discover the most abstruse facts about how bits of matter move and interact with one another. That is what enabled modern physics to go beyond the ancient atomists in understanding the nature of the elementary objects. But despite the acuity of its vision of regularities, physics was blind to a more basic aspect of the world. It failed to recognize that the job of science is not just to describe the regularities by which it is possible to predict and control what happens in the world, but also to describe the basic substances that constitute those regularities (not just the particles to which they refer, but all the substances that cause them ontologically). It comes from a failure to recognize that ontology can be explanatory in its own right and that ontological-cause explanations are a deeper kind of explanation from efficient-cause explanations, that is, from the same oversight that led to the Einsteinian revolution in the first place.

The challenge of quantum mechanics. Like the Einsteinian revolution, quantum mechanics might also be thought to pose a challenge for ontological philosophy. The quantum revolution has also overthrown assumptions of classical physics about the nature of the world, and if spatiomaterialism were unable to explain ontologically why the laws of quantum mechanics are true, physics might provides a reason for denying that ontological philosophy can use spatiomaterialism as the foundation for doing philosophy in a new way, despite its explanation of relativity theory.

The quantum revolution does not, however, challenge spatiomaterialism in the same, direct way as relativity. Quantum mechanics has not led to any consensus among physicists about the nature of what exists that is incompatible with spatiomaterialism.

The Einsteinian revolution is generally assumed to be the discovery of something that directly contradicts spatiomaterialism. In contemporary physics, absolute space and absolute time have explicitly been replaced by spacetime. But absolute space and time are entailed by the assumption that space and matter are substances enduring though time. Thus, in order to defend the use of spatiomaterialism as the foundation for this philosophical argument, I had to show that what Einstein’s two theories imply about the world could be explained on the assumption that space and time are absolute.

The quantum revolution has not led to ontological beliefs that directly contradict spatiomaterialism. This is partly because there is no consensus among physicists concerning what quantum mechanics implies about the nature of what exists. There is no dispute about the laws themselves; they are among the most precise and highly confirmed in physics. But scientific realism about quantum mechanics does lead to general agreement in ontological beliefs. There are so many disputes about the kinds of entities that are required for the laws of quantum mechanics to be true and they are so intractable that most physicists beat a hasty retreat to their empirical method and take cover by simply pointing out that its laws are the best way of predicting and controlling the relevant phenomena.

To be sure, there are ontological interpretations of quantum mechanics that are incompatible with spatiomaterialism. For example, some philosophers take measurements in quantum mechanics (involving the so-called “collapse of the wavefunction”) to be an event that depends on a conscious mind coming to know something about the world, and that is to assume that mind is a fundamentally different kind of substance from matter, which is is a form of immaterialism that spatiomaterialism rejects. Another interpretation, called the “many worlds view,” interprets measurement in quantum mechanics (again, the collapse of the wavefunction) to be the occasion of the universe splitting into different universes in which each of the different possible outcomes of each measurement are realized, which is not compatible with the world being constituted by substances. However, the possibility of such views is hardly an objection to spatiomaterialism, as long as it is possible to give an ontological interpretation of quantum mechanics that is compatible with spatiomaterialism. Thus, the issue is whether all possible ontological interpretations are incompatible with spatiomaterialism. It was the universal assumption that Einsteinian relativity is incompatible with space being absolute that forced us to take out a mortgage on spatiomaterialism, promising to show how it can explain Einstein’s two relativity theories ontologically as a condition of using it as the foundation for ontological philosophy.

To be sure quantum mechanics did overthrow the classical view of the nature of matter. But that does not necessarily challenge spatiomaterialism, because spatiomaterialism is no more committed to the classical view of matter than it is to the classical view of space. The relevant issue is whether it is possible to explain the truth of the laws of quantum mechanics by making assumptions about the nature of matter (and space) that are consistent with spatiomaterialism. 

Materialism in general is not generally thought to be what is refuted by quantum mechanics. On the contrary, many physicists who are quite confident of the truth of quantum mechanics would consider themselves “materialists” in the broad sense in which that term is used to classify ontological positions.

The question is what more specific essential nature material substances must have in order for quantum mechanics to be true. It is clear that the regularities described by quantum mechanics cannot be explained ontologically by the kinds of material objects and light waves recognized by classical physics. But spatiomaterialism does not have to defend that view of matter. Indeed, as we have seen, its explanation of why the laws of classical physics are true (insofar as they are true) depends on assumptions about the nature of matter that are not part of classical physics. I assumed, for example, that kinetic energy is a form of matter that exists in addition to the rest masses of material objects, and that potential energy is as form of matter (force field matter) that is already counted in the rest masses of the objects exerting the forces. And in explaining the truth of the special and general theories of relativity, I have made further non-classical assumptions about the nature of the world — for example, that there is an inherent motion in space and that it can itself be accelerated and have a velocity relative to space.

This is not to say that there is nothing puzzling about quantum mechanics. There are two, basically different ways that it might seem to challenge spatiomaterialism directly. One has to do with a long recognized indeterminacy about its predictions, and the other is a more recently discovered problem about action at a distance (deriving from Bell’s theorem).

Indeterminism. The laws of quantum mechanics do not describe nature as having deterministic causal connections among states of affairs. Those laws often imply only that, given everything that can be known about a given situation, any of a number of different states might follow (or precede) it. The most that can be done is to assign a probability to each of those possible outcomes.

This is fundamentally different from classical physics, for its laws were deterministic. As Laplace pointed out in the eighteenth century, if the basic laws of classical physics are true, then given a complete description of the current situation (even the state of whole universe), it would be possible, in principle, to predict any future state (or even any earlier state). The state of the universe (or any closed system) at any one moment determines its state at every other moment.

Even in very limited situations, the laws of quantum mechanics do not usually support such deterministic predictions. Given a complete quantum mechanical description of a situation, there is a range of possible events that can happen (such as what measurements will reveal), and there is no way of saying which one it will be (though it is possible to assign probabilities to the alternatives). Thus, physics no longer assumes that complete knowledge of the current state of the universe would make it possible to predict what would happen.

This lack of precise predictability comes from the nature of the Schrödinger equation. Its solution for a given situation is a wavefunction which is a complete quantum description of that situation (in pre-relativistic quantum mechanics). It describes precisely how the quantum system evolves as time passes, just like a wavefunction in classical physics. But the Schrödinger wavefunction is not classical, because it involves complex numbers (containing i, or the square root of minus one), and the space in which the wave is contained is a “configuration space,” which is a space with three times as many dimensions as there are particles involved in the situation being described. There is no obvious way to relate such a wavefunction to the natural world. The standard interpretation of the Schrödinger wavefunction takes the square of the amplitude of the wavefunction (for a single particle) in any small region of space to represent the probability of finding the particle at that location. (And there are mathematical operators on the wavefunction that predict measurements, but they cannot predict precisely both of any pair of complementary variables, such as the position and momentum of an electron.)

This limitation on precise predictions of what will happen is summed up in the famous Heisenberg uncertainty principle. This principle can be taken as reflecting either an indeterminism about the world itself or as merely an incompleteness in what can be known about it. Though in either case, it is a limitation in principle, rather than practice, a mere incompleteness in our possible knowledge about the world would not contradict spatiomaterialism. Substances enduring through time could still constitute causal connections, even if some aspects of those substances cannot be measured precisely. Furthermore, even if this uncertainty did derive from an indeterminism in the nature of what happens independently of how it is known, it would not necessarily be incompatible with spatiomaterialism.

Indeterminism would contradict spatiomaterialism if it was incompatible with the world being constituted by substances enduring through time. Such an extreme indeterminism would be true, if the predictions supported by quantum mechanics corresponded to all the causal connections that there are between the properties that hold at one moment and the those that hold at the next. To hold that what is unpredictable is not determined at all is incompatible with any explanation of the world as constituted by substances enduring though time, because it is to assume, in effect, that something comes from nothing. What is unpredictable about the next moment would not depend in any way on what existed at the previous moment, and since it would have to come from nothing at all, extreme indeterminism would contradict the assumption that the world (and all its aspects) are constituted by substances enduring through time. Though this does not bother epistemologically minded naturalists, it would be a death blow to ontological naturalism.

A less extreme form of indeterminism is compatible with an ontological explanation of the natural world, though it is still hard to swallow. Indeterminism might hold that what is unpredictable according to the Heisenberg principle is a result of an inherent randomness in the essential nature of the matter making up the world. This would be more than a mere limitation in what we can know about the determining conditions, because it also would be a limitation in what even God could know. There would be no need to believe that something comes from nothing, because what exists at the next moment would be constituted by the same substances that constituted the world at the previous moment. But here would be no aspect of the nature of those substances at the previous moment that determines which of certain aspects it will have the next moment, because the randomness would be an aspect of the essential nature of the kind of matter that constitutes the world. The randomness would be a temporally complex aspect of the essential nature of matter, for it would make the connections between properties that substances have at different moments random. It would be as if matter itself contained a randomness generator that even God could not use to predict what will happen (though God would presumably still know the future, since he is the creator of all the moments of the world). Though such a view about the nature of matter would be consistent with spatiomaterialism, it would not be as good as one that could give a genuine ontological explanation of what happens, that is, which explains what happens as aspects of the world that follow from the natures of the basic substances as they endure through time constituting the world.

However, The Heisenberg uncertainty principle does not preclude a genuine ontological explanation of what is unpredictable. To hold that quantum uncertainty is merely a limitation in what beings like us, who are parts of the world, can know about the world is to hold that what happens does have a cause, but that we cannot know precisely what it is. This is to interpret the probabilistic nature of quantum mechanics as an incompleteness in our knowledge, rather than as indeterminism about the world. It assumes that there is some “hidden variable” that is actually determining what happens, though for some reason, that variable cannot be measured. That is not incompatible with spatiomaterialism, because the reason for the Heisenberg uncertainty could be that the interactions required for scientists, as material objects in space, to know about particular conditions in the world so disturb the world that they alter the conditions being known. That limitation must, of course, be caused by the basic nature of those interactions. But that does not mean that it is impossible to identify the nature of the hidden variable. It means only that its quantity cannot be measured accurately in any particular case. And having inferred to spatiomaterialism as the best ontological explanation of the world, we may be in a better position to identify the nature of the hidden variable that makes quantum mechanics incomplete.

Bell’s theorem. Though the traditional puzzles about the apparent indeterminism of quantum mechanics do not necessarily contradict spatiomaterialism, there is a more recently discovered implication of quantum mechanics that may. It occurs when particles separate from one another in a way that gives them opposite orientations of a quantum property called “spin.” John Bell showed that when such particles move away from one another in opposite directions, it is possible for a measurement made of one particle at one location to predict (probabilistically) measurements that are made at another location more accurately than would be possible if the particles had the properties being measured from the time they parted from one another. These “Bell correlations,” as I will call them, seem to imply that spin is not a property that the particles carry with them locally, but one that depends on the entire system, including both particles rushing away from each other.

This suggests according to a standard interpretation of quantum mechanics that the measurement of one particle affects the other particle (that is, that such effects are part of what is called the “collapse of the wavefunction”). But if measurement does have such effects, then it would have to be able to have its effect faster than the velocity of light, and that seems to contradict the principle of local action. I have assumed that what happens in one part of space cannot affect what happens elsewhere any faster than the velocity of light, for that velocity is determined by the inherent motion in space.

There is, however, something suspicious about the Bell correlations. There is no other evidence of faster than light effects in nature. Furthermore, it has been shown that, whatever is going on, Bell correlations are the kind of signal that can be used to communicate information. They are peculiarly lacking in further consequences.

It is not clear, therefore, that this departure of quantum mechanics from Bell’s theorem (about what local action entails) depends on one measurement affecting the other measurement causally. However, worries about the possibility of action at a distance will probably not be put to rest completely unless it is explained how it is possible for quantum mechanics to make such predictions. Thus, there something that needs explaining.

There is, therefore, reason to explore the ontological explanations of quantum mechanics that are opened up by spatiomaterialism. We would be justified in using spatiomaterialism as the foundation for ontological philosophy without explaining why quantum mechanics is true. But if its explanation of the aspects of the natural world to which the equations of quantum mechanics correspond did help clear up the quantum puzzles, there would be an additional reason for believing that spatiomaterialism is true.

In the first section, I will review the traditional puzzles about the nature of matter posed by quantum mechanics.

In the second section, I will introduce several new assumptions about the nature of space and matter and show how they would enable spatiomaterialism to explain the forms of matter that were assumed in explaining the truth of the laws of classical physics.

The third section will return to the quantum puzzles and show how the proposed ontological assumptions would explain those puzzling phenomena ontologically, including a response to the challenge that seems to be posed for spatiomaterialism by the more recent discovery of Bell correlations.

This more detailed ontological theory about the nature of matter is offered in a speculative vein. It differs from the ontological explanation of relativity theory, because no such explanation must be given in order to use spatiomaterialism for philosophical purposes. And it differs from the arguments to come about global regularities, because they attempt to prove that certain proposition are ontologically necessary truths. The reason that this ontological explanation of quantum mechanics is not ontologically necessary is that there may be other ontological explanations of quantum mechanics that are also consistent with spatiomaterialism (and what is says about relativity theory). Thus, the most I would claim to show is that some such ontological explanation is true. It may not be this one, but it will be clear, I believe, that there is some way of explaining the truth of quantum mechanics on a spatiomaterialist foundation. And since speculation is valuable as a way of exploring the possibilities, this particular version of spatiomaterialism may contribute to the discovery of the more complete truth about the natural world.

This explanation of quantum mechanics is, like its explanation of relativity theory, ontological, rather than mathematical. I will be trying to show how the new phenomena predicted by quantum mechanics can be constituted by space and matter as substances enduring through time, not that there is a better efficient-cause explanation of what happens. It does not claim to make any new predictions of what happens in the world.

Though I will give reasons for believing that this ontological explanation is quantitatively accurate (or can be made so), I will not try to show in detail how the formidable mathematical formalism of quantum mechanics relates to the world. Such a mathematical argument would take us too far afield. And in any case, it has already been done by David Bohm. (See Bohm, 1993, with Basil J. Hiley.) That is, the ontology I will be proposing is a variation on the ontology that Bohm shows to correspond to the Schrödinger equation, the basic equation of quantum mechanics, and thus, if Bohm’s ontology is a possible explanation of the truth of quantum mechanics, then so is this one.

There are many good accounts of quantum mechanics, but a reasonably accessible one that I have recently found useful is Jim Baggott's The Meaning of Quantum Theory.

In most cases, it will be clear that the kinds of assumptions I will be making can be refined to made them quantitatively adequate. This is much the same attitude I took in explaining ontologically the truth of general relativity, except that in the case of quantum mechanics, I also leave open the choice between various more detailed, alternative ontological assumptions. Thus, in order to show that it is not possible to explain the truth of quantum mechanics ontologically in this way, it would be necessary to show that none of these possibilities can be quantitatively adequate for the whole range of quantum phenomena.

Nor do I claim that the ontological theory being presented here is the best spatiomaterialist explanation of quantum mechanics, only that it (or one much like it) is possible in the sense of accounting for all the relevant phenomena. There may be ways in which space and matter existing together as a world can explain the truth of quantum mechanics more simply. That would be interesting and preferable. But it is not the crucial point, because the possibility of such an ontological explanation is all that is relevant to rest of ontological philosophy. And seeing how it is possible is the first step toward discovering the best such theory.