In this article the Dirac equation is used as a guideline to see the historical emergence of the concept of quanta, associated with the quantum field. In P. Jordan’s approach, electrons as quanta result from the quantization of a classical field described by the Dirac equation. With this quantization procedure – also used for the electromagnetic field – the concept of quanta becomes a central piece in the applications of quantum electrodynamics. This does not seem to avoid the apparent impossibility of using the concept of quanta – and with it the common interpretation of quantum fields – when interacting fields are considered together as one complete system. In this article it is defended that the type of analysis that leads to so drastic conclusions is avoidable if a clear distinction is made between the mathematical framework of the theory and the particular physical models (used in the empirical corroboration of the theory) that are constructed using the theory. When dealing with models there really is no system of complete interacting fields, and what we have is a description of the interactions between distinct fields. In this situation the concept of quanta is central in the description of interacting fields, the Fock space being the natural mathematical structure that permits maintaining the quanta concept when considering the interaction between fields.
In this article the Dirac equation is used as a guideline to the historical emergence of the concept of quanta, associated with the quantum field. In Pascual Jordan’s approach, electrons as quanta result from the quantization of a classical field described by the Dirac equation. With this quantization procedure – also used for the electromagnetic field – the concept of quanta becomes a central piece in quantum electrodynamics. This does not seem to avoid the apparent impossibility of using the concept of quanta when interacting fields are considered together as a closed system. In this article it is defended that the type of analysis that leads to so drastic conclusions is avoidable if we look beyond the mathematical structure of the theory and take into account the physical ideas inscribed in this mathematical structure. In this case we see that in quantum electrodynamics we are not considering a closed system of interacting fields, what we have is a description of the interactions between distinct fields. In this situation the concept of quanta is central, the Fock space being the natural mathematical structure that permits maintaining the concept of quanta when considering the interaction between the fields.