 Teller (1995) argues that the Fock space or “occupation number” representation does support a particle ontology in terms of field quanta since these can be counted or aggregated, although not numbered. The degree of excitation of a certain mode of the underlying field determines the number of objects, i.e. the particles in the sense of quanta. Labels for individual particles like in the Schrödinger many-particle formalism do not occur any more, which is the crucial deviation from the classical notion of particles. However, despite of this deviation, says Teller, quanta should be regarded as particles: Besides their countability another fact that supports seeing quanta as particles is that they have the same energies as classical particles. Teller has been criticized for drawing unduly far-reaching ontological conclusions from one particular representation, in particular since the Fock space representation cannot be appropriate in general because it is only valid for free particles (see, e.g., Fraser 2008). In order to avoid this problem Bain (2000) proposes an alternative quanta interpretation that rests on the notion of asymptotically free states in scattering theory. For a further discussion of the quanta interpretation see the subsection on inequivalent representations below.