The inner workings of subatomic particles, such as protons, neutrons, and electrons, are described by the principles of quantum mechanics and the Standard Model of particle physics. According to these theories, subatomic particles are not considered to be solid objects with well-defined boundaries like macroscopic objects. Instead, they are described as quantum entities that exhibit both particle-like and wave-like properties.
At the heart of the Standard Model are fundamental particles, which are point-like entities without any internal structure. These particles are categorized into two main types: fermions and bosons.
Fermions: Fermions are particles that make up matter. They are further classified into two groups: a. Quarks: Quarks are elementary particles that are the building blocks of protons and neutrons. They have fractional electric charges and interact through the strong nuclear force. Quarks are never observed in isolation but are always found in combinations of two or three, forming composite particles like protons and neutrons. b. Leptons: Leptons are elementary particles that include electrons and neutrinos. Electrons are negatively charged and orbit around atomic nuclei, while neutrinos have very little mass and rarely interact with matter.
Bosons: Bosons are particles that mediate the fundamental forces of nature. They include photons, which carry the electromagnetic force, as well as W and Z bosons and gluons, which mediate the weak and strong nuclear forces, respectively. The Higgs boson, discovered in 2012, is associated with the Higgs field and gives other particles their mass.
The behavior and properties of subatomic particles are described by their quantum mechanical wave functions. These wave functions encode the probabilities of different outcomes when measuring a particular property of a particle, such as its position, momentum, or spin. The wave-like nature of particles allows them to exhibit phenomena such as interference and superposition.
It's important to note that while we have a good understanding of the behavior and interactions of subatomic particles, the question of what goes on at the most fundamental level, beneath the point-like nature of particles, remains an open area of research. Theoretical physicists continue to explore deeper levels of understanding through experiments and the development of new theories, such as string theory and quantum gravity, in an attempt to explain the fundamental nature of particles and their constituents.