The existence of three quarks is indeed an interesting aspect of the subatomic realm, but it arises from the properties of the strong nuclear force and the way quarks interact with it. This is a concept known as color charge and is described by the theory of quantum chromodynamics (QCD).
In the theory of QCD, quarks are considered to carry a property called color charge, which comes in three types: red, green, and blue (again, these are just labels and have no relation to the colors we perceive). The concept of color charge is analogous to electric charge in electromagnetism.
The strong nuclear force, which is responsible for binding quarks together to form particles such as protons and neutrons, is mediated by particles called gluons. The strong force is unique in that it becomes stronger as quarks are pulled apart, making it impossible to observe isolated quarks. This phenomenon is known as color confinement.
To maintain color confinement, quarks must combine in such a way that the resulting combinations are color-neutral. This means that the combination of three different color charges (e.g., one red, one green, and one blue) or a combination of a color charge and its corresponding anticolor charge (e.g., one red and one antired) results in a color-neutral particle.
In the context of the three-quark combinations, these are known as baryons. Examples of baryons include protons and neutrons, which consist of three quarks each. The three-quark combination ensures that the resulting particles are color-neutral and can exist as bound states.
The number three, therefore, arises from the requirement of color confinement and the need for color-neutral combinations of quarks. It is important to note that there are other types of particles in the subatomic realm, such as mesons, which consist of a quark and an antiquark. However, the specific combination of three quarks is necessary to form color-neutral baryons.
While the number three may seem peculiar, it is a consequence of the behavior of the strong nuclear force and the properties of quarks in the context of quantum chromodynamics. It is a fundamental aspect of our current understanding of the subatomic world.