Quantum fields are not merely concepts used to describe the behavior of nature; they are fundamental entities that are believed to exist in our physical world. In modern physics, quantum field theory is a framework that describes the behavior of particles and their interactions based on the concept of quantum fields.
According to quantum field theory, particles are understood as excitations or quanta of their corresponding quantum fields. These fields permeate all of space and time and interact with each other, giving rise to the phenomena we observe. The interactions and behaviors of particles are described in terms of the dynamics of these fields.
Quantum field theory has been tremendously successful in describing and predicting a wide range of physical phenomena, from elementary particle interactions to the behavior of condensed matter systems. It is the basis for our understanding of the Standard Model of particle physics and plays a crucial role in theories like quantum electrodynamics (QED), quantum chromodynamics (QCD), and the electroweak theory.
While quantum fields are not directly observable in the same way as particles, their effects are observed through experiments and measurements. The predictions made by quantum field theory have been extensively tested and confirmed through various experiments and observations.
So, while quantum fields can be thought of as mathematical tools used to describe the behavior of particles and their interactions, they are considered to be more than just conceptual. They are fundamental entities that underlie the fabric of our physical reality.