In quantum field theory (QFT), fields are indeed described as excitations or fluctuations of energy that permeate spacetime. However, the idea that fields are "stacked on top of one another" is not an accurate representation of how fields interact or are organized.
In QFT, fields are treated as separate entities associated with different particles or types of interactions. Each field has its own distinct properties and characteristics. For example, there are different fields associated with electrons, photons, quarks, and other elementary particles. These fields are quantized, meaning that they are described in terms of discrete units or quanta, which correspond to particles.
The interactions and behaviors of fields in QFT are governed by the principles of quantum mechanics and the specific equations of the theory. These equations incorporate the concept of local interactions, where fields at different points in spacetime can interact with each other through various processes.
While it might be tempting to think of fields merging into a "soup" due to their nature as energy, the mathematical formalism of QFT and experimental observations do not support such a notion. The distinct fields in QFT remain separate entities with their own properties and interactions. The specific interactions between fields are determined by the mathematical structure of the theory, including the symmetries and coupling constants.
It's important to note that the notion of "separation" between fields in QFT is not a spatial separation in the traditional sense. Instead, it refers to the distinct properties and interactions associated with different fields. The interactions between fields are mediated by exchange particles, such as photons or gauge bosons, which allow for the transfer of energy and momentum between the fields.
Overall, the organization and behavior of fields in QFT are described by the mathematical framework of the theory, which allows for distinct fields to exist and interact while preserving their individual properties.