Subatomic particles, such as electrons, protons, and neutrons, are considered point particles in classical physics, meaning they are modeled as having no size or spatial extent. However, it's important to note that this is a simplification used in classical models. In reality, particles are described by quantum mechanics, which introduces a probabilistic nature and some additional complexities.
In the framework of quantum mechanics, particles are not thought of as tiny billiard balls with definite positions. Instead, they are described by wave functions that represent their probability distributions. When two particles approach each other, their wave functions can overlap, indicating a possibility of interaction or "touching" in a sense.
The concept of "touch" at the subatomic level becomes more abstract. It doesn't mean particles physically collide or come into direct contact as we typically understand it in macroscopic terms. Rather, it refers to the interaction of their fields or the exchange of fundamental forces between them. For example, electrons repel each other due to their electric charges, and this repulsion prevents them from occupying the same quantum state.
In summary, subatomic particles are treated as point-like entities in classical physics, but in quantum mechanics, they are described by wave functions and interact through their fields or the exchange of forces. The notion of "touch" becomes more nuanced and relates to the probability of interaction rather than physical contact.