Problems with the Materialist world view
The materialist philosophy reached its apogee in the post Newtonian world of the nineteenth century. It was based on the concept that the world was fashioned to operate on certain exact laws given by Newton in his epic work on mechanics "Principia Mathematica".
The laws in turn pivoted on the concepts of forces and particles. A force was a push or a pull which could change the motion of matter. Matter in turn was considered to be an assemblage of small particles. Given a certain arrangement of particles and the size and direction of the forces affecting them, Newton's laws could predict exactly what would happen to all of them. Since the universe was just a large assemblage of particles, in principle at least it was as predictable as a watch.
But what exactly were the "particles" that the laws operated on? particles were visualized as sub-microscopic, absolutely elementary, perfect, incorruptible, and indivisible. The notion dates back to a Greek school of thought called atomists of which Democritus is the name most known. Our word "atom" is derived from a Greek word meaning unsplittable.
One post Newtonian view was that these particles were so perfect that they occupied no real space at all but were just mathematical points. This turned out to be totally useless for physics, yielding all manner of contradictions and absurdities. In practice therefore a "particle" came to be most often pictured as a kind of tiny billiard ball. The Victorians were familiar with the game, and it gave a comfortable way of visualizing the microscopic realm. Newton's laws could be readily applied, to these particles by just making a few convenient assumptions such as that they were perfectly rigid, perfectly hard, etc. In other words an ideal Billiard ball.
Now there is a frame of mind that is only satisfied when it has reduced things to their "real", and "concrete" essentials, the elementary particles of which things are constructed. Characteristics like taste or slipperiness, are considered merely results of the different ways the elementary particles are arranged, and therefore secondary properties, merely effects, and not real, all that is actually there are the elementary particles and their arrangements. Democritus expressed it this way: " According to convention there is a sweet and a bitter, a hot and a cold, and there is a color. In truth there are atoms and a void."
The particle therefore was ontologically ultimate, it was supposed to represent something with a self evident rock bottom reality.
However upon closer examination something interesting happens, the very idea of a particle turns out to be a kind of wishful thinking. In the physical universe there are no particles, at least not as conceived above.
Lets start with billiard balls. An actual billiard ball rolled across the table leaves a streak of its own material behind, and gets slightly, but measurably lighter. If left to itself the billiard ball will slowly evaporate into the air or space around it, becoming lighter and raggedier as it goes along. ( To evaporate completely might take longer then the age of the universe up to now, but for this discussion we are in no rush. ) It is doing this because it is slowly losing from its surface the atoms of which it is composed. Clearly a real billiard ball does not very well exemplify a particle.
What about the very atoms that are escaping the surface and traveling through space as little missiles ? Up until about 1900, scientists thought that atoms were perfect immortal and absolutely indivisible particles. Then experiments began to show that they could be broken up into positive particles ( Protons ) negative particles (Electrons), and neutral particles (Neutrons).
Then further difficulties emerged. It became apparent experimentally that protons, neutrons, and electrons, could not be pinned down in any one place but were by their very nature delocalized . (Some formulations had it that the particle had an exact position ,but that this position could never be known exactly). There was no way around this, it was formalized in a law called the uncertainty principle. Further in some experiments they behaved strikingly like waves, (interfering with each other like waves in water, and refracting and diffracting the way waves do.
It then seemed that protons and neutrons were also probably made up of yet other particles called quarks These were so strange in their behavior that in addition to the usual problems of not being anywhere in particular, they could not be isolated separately, and many physicists feel, can exist only in relation to other quarks, and not independently.
Now at this point I must focus on a critical distinction : The difficulty is not that atoms could be split into smaller particles, that in itself is no threat to the CONCEPT of a true particle. It just means that historically when they thought they had reached the last unsplittable particle and named it "atom" they were premature. It could just mean that the real and proper atoms were someplace further down in scale, and would eventually be found, and then they could rename the old ones Quasi-atoms, and the new ones Ulti-atoms or some such.
What I am pointing to in this capsule history of atomic discoveries is much more fundamental and all pervasive than a mere nomenclature mistake. Simply stated it is this:
There are no particles. In the whole history of physics, so far, there are no actual particles at any scale. Every real object in the world has traits that are incompatible with what you "want" from a particle. Nature affords not one single example of the beast.
Further discoveries of yet smaller things cannot get you out of this difficulty because at the scale of atoms and below everything must be delocalized by the uncertainty principle, so true particles cannot be discovered by digging yet deeper.
If then there exist no particles, what then is a particle really? It is a Word we use, it is a platonic ideal, a composite abstraction amalgamated from separate properties of real things.
Therefore, any reduction to "particles and the Void" as a representation of a world view which is based on the most ultimately concrete and physically real entities, is in fact resting on the shifting sands of a complex hybrid, a purely abstract chimera of a notion, of which there is no single instance in the physical world.
This is not at all meant to suggest that it is not a useful notion. Richard Feynman famously declared that the fact that the world was made of atoms was the most valuable single thing that Science had discovered, and chemistry in particular only made real progress when it became common to think of all substances as made of discrete particles. It is not a wrong or useless concept at all, it's merely that on the philosophic level of ontological status, it reveals itself upon examination to be incredibly non-ultimate.
P.S. This sheds some light on light. When light was discovered to behave as a wave or a particle, or a hybrid of both, this was often called a paradox: The "duality" of light. It should not come as such a shock that light doesn't behave in all circumstances, or in all ways, as a particle should, in view of the fact that nothing else does either.
Contact: David Green