Particlehood
Particlehood refers to the status or quality of being a particle within physical theories and related philosophical discussions. It concerns what counts as a particle, how particles can be identified or distinguished, and under what conditions a system can be described as composed of particles rather than fields or other entities. The meaning of particlehood is theory-dependent and often approximate.
In classical mechanics, particles are idealized localized objects with well-defined positions and trajectories in space and
In quantum mechanics, the notion becomes more nuanced. Identical particles obey permutation symmetry, and individual identity
In quantum field theory, particles are excitations of underlying fields. Creation and annihilation operators act on
Philosophical discussions address whether particles are primitive constituents of reality or emergent from fields, the problem