2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/55819We review the heuristic arguments suggesting that any thermal quantum field theory, which can be interpreted as a quantum statistical mechanics of (interacting) relativistic particles, obeys certain restrictions on its number of local degrees of freedom. As in the vacuum representation, these restrictions can be expressed by a `nuclearity condition'. If a model satisfies this nuclearity condition, then the net of von Neumann algebras representing the local observables in the thermal representation has the split property.plain tex, 29 pages; heuristic arguments leading to the nuclearity conditon revisedHigh Energy Physics - Theorytext