Quantum Mechanics
Most branches of physics treat "elementary particles" just as particles - i.e. points or solid little balls of matter and charge. This statement also applies to atomic and nuclear physics. The theoretical foundation of these sciences is Quantum Mechanics. In the mathematical framework of Quantum Mechanics are the basic entities usually represented either by points of matter and charge or by spheres, where matter and charge is uniformly distributed throughout the sphere. The main difference between a classical (or Newtonian) particle and its Quantum Mechanical counterpart is that, while the position and outline of the former can be determined exactly, this is not so for the latter. Nevertheless, as far as the interactions on the atomic and nucleonic levels are concerned, Quantum Mechanics is doing pretty well. However, when it comes to the levels of "elementary particles", that framework has at least one crucial drawback. In the Quantum Mechanical framework the basic entities have existed in their current shape forever and will continue to exist in this shape forever. Consequently, Quantum Mechanics provides no clues on how or why "particles" come into existence nor how and why they vanish. A natural consequence of this defect is that a large variety of well-known processes, such as e.g. those illustrated above, cannot be treated within the frames of Quantum Mechanics.
In order to be able to consider the immanent qualities and substance of "elementary particles", physicists have to turn to the framework of Quantum Field Theory. Essentially, Quantum Field Theory is a specialized set of mathematical formulas and rules by means of which one, in a consistent and very detailed manner, can consider questions such as 'what is the true origin and intrinsic nature of matter, charge, force etc.' and 'what is really going on at the most fundamental levels of nature'. Actually, Quantum Field Theory is not a theory as such but is more like a complex and content rich language well equipped for describing and "verbalizing" realms where other languages (such as English or the mathematics of Quantum Mechanics) have to give up.
The overall result of the sequence of processes, illustrated by the image above, is that two entities - a charm-quark and its anti-quark - are split into six other entities. The actual appearances of this sequence are well-confirmed by "particle" physics experiments. The same statement applies to a large variety of similar processes with any other set of "elementary particles" in the initial stage. Thus, these entities obviously are neither elementary nor indivisible, little balls of matter. No, - according to Quantum Field Theory, the "elementary particles" are discrete, vibrational states of certain underlying fields. Consequently, the fundamental constituents of the physical world are not "particles". The fundamental constituents are fields. - This is the reason for hitherto having put the word 'elementary' in quotes. On the next page the reason for the extensive use of quotes around the word 'particle', will be revealed.
