The concept of "touching" at the subatomic level is different from our everyday macroscopic understanding of objects physically coming into contact with each other. In the realm of subatomic particles, such as electrons or quarks, the notion of size and contact becomes more nuanced due to the principles of quantum mechanics.
In quantum mechanics, particles are described by wavefunctions that represent the probability distribution of their positions or other observable properties. The wavefunctions of particles can overlap, indicating a region of space where the particles have a non-zero probability of being found. When two subatomic particles, such as electrons, come into close proximity, their wavefunctions can overlap, leading to interactions between them.
However, it's important to note that the wavefunctions of subatomic particles do not represent their physical extent in the same way as macroscopic objects. The wavefunctions describe the probabilistic nature of finding a particle at a particular location or exhibiting a specific property. The idea of particles having no size in classical terms arises because the concept of point-like particles is often used as a simplification in many models and calculations.
In quantum field theory, particles are treated as excitations of underlying fields. These fields pervade all of space, and particles arise as localized disturbances or quanta of these fields. When particles interact, they exchange other particles or interact through fundamental forces mediated by gauge bosons.
So, while subatomic particles may not have a size in the classical sense, they can still interact and influence each other due to the overlapping of their wavefunctions or through the exchange of other particles. The precise nature of these interactions is described by quantum field theory and quantum electrodynamics, which have successfully explained and predicted various phenomena in the subatomic realm.