Physics is full of leaky abstractions. Solid? Leaky abstraction (melting). Ideal gas? Leaky abstraction (van der Walls). Molecule? Leaky abstraction (chem

Physics is full of leaky abstractions. Solid? Leaky abstraction (melting). Ideal gas? Leaky abstraction (van der Walls). Molecule? Leaky abstraction (chemical reactions). Atom? Leaky abstraction (ionization, fusion, fission, alpha and beta decay). Proton? Leaky abstraction (sometimes you have to care about the quarks).