[nyssos]

> but you hear things about quantum fields

Fields are not exotic objects at all: they're just assignments of some quantity (a number, a vector, a linear transformation, something more complicated) to each point in some space. Take the elevation of every point on the Earth's surface, for instance: that's a field. Wind velocity is a field. The stresses inside some solid material are a field. They're absolutely foundational to physics.

> virtual particles

Virtual particles are a mnemonic device for approximating certain very complicated integrals, they don't actually exist.

> quantum gravity

Quantum gravity is a topic, not (yet) a particular thing. We have an extremely good theory of gravity (general relativity), and an extremely good theory of most of the rest of physics (the Standard Model, and more generally quantum field theory) - and they're impossible to reconcile with each other. So despite their empirical success, we know for a fact that both are false. What we want is a single consistent theory that incorporates both fundamental particle physics and gravity: a theory of quantum gravity. And while we know roughly what sort of experiments would allow us to investigate it directly, they would require particle colliders larger than the Earth to carry out. So for the moment all the theorists can really do is investigate candidate theories in preparation for the day when someone (hopefully) figures out an easier way to test them.

> what in quantum mechanics is considered “canon”

All of the formalism, very little of the interpretation.