Quantum Field to Layman How would you describe a Quantum Field in layman's terms? Is is some function that provides information about the universe in a particular space-time region? My motivation for the latter question is as follows. I read that quantum wavefunctions can be promoted to operators that can create and destroy particles. The notation would be something like $\psi(x) \to \hat{\psi(x)}$ (antihalation) and $\psi^*(x) \to \hat{\psi(x)^\dagger}$ (creation). Quantum fields are responsible for creating and destroying particles and creating and destroying particles can provide information; wavefunctions provide information and are related to creation and destruction via second quantization.
What makes a quantum field more fundamental than "particles"? In classical physics, particles seem just as fundamental as fields because particles have many fixed or absolute properties (like charge and mass) and these properties of particles give rise to many classical fields (mass $\to$ gravitational field and the warping of spacetime and charge $\to$ electric fields). So in classical physics the properties of particles gives rise to classical fields and one can say that many kinds of fields are just properties of particles. In quantum mechanics, the word "particle" is controversial due to wave-particle duality and so in quantum mechanics the picture of the particle breaks down; additionally, the notion of the wavefunction loosens the notice of absolute properties, since many properties of "particles" become probabilistic. Is that why the quantum field approach was adopted, since the notion of particle breaks down in quantum mechanics and one needs to find something "better" to replace it?
This might be really silly, but it follows from the previous question. In early quantum mechanics classes we learned about slit experiments with electrons. Let's say someone shoots an electron in front of two slits and places a detector in front of slit A. The detector always measures the electron and I have learned that this suggests that electrons "know" what we want to measure and give us what we want. Are electrons really that "smart" or is it some kind of quantum field that knows we want to measure the electron at slit A and produces an electron at slit A? Or is there some other reason.
 A: There are several questions here. I will try to answer the first one, in the title.
Consider a lake on a calm day. There are no waves on its surface, but there is nonetheless water everywhere in the lake. When wind excites the surface of one end of the lake, or if a rock falls into it, waves then appear in the lake surface in those places and travel from place to place across the surface of the lake.
Analogously, a quantum field exists throughout space, and when it is excited or acted on by something that is coupled to it, bunches of waves appear where the excitation is occurring and travel from place to place through space.
You can define a quantum field to be associated with each type of known particle in the universe, and define the particles as excitations of that field. You can also write rules for the particular way the excitations of those different fields might interact.
When you do this, you discover that the fields can be organized into distinct groupings based on how their excitations interact with themselves. For example, if the waves of one group type happen to collide they might pass freely through one another and continue on their way as if nothing happened (as if they were water waves), while those of another general type might bounce off one another in different directions (as if they instead were solid objects).
In quantum field theory, fields are specified by their quantum mechanical spin (for which there is no "classical" analogue); this is what physicists mean when they say a certain type of particle is a "spin zero" or "spin one-half" or spin "one" or "spin two" field, about which the experts have written great volumes of text.
I invite them to offer here their own more detailed takes on this topic.
