Fields in quantum mechanics really just describe the ways that the force fundamental forces (gravitational, electromagnetic, strong nuclear, and weak nuclear) t

Fields in quantum mechanics really just describe the ways that the force fundamental forces (gravitational, electromagnetic, strong nuclear, and weak nuclear) travel around. The double slit experiment, which this article focusses on, looks at photons. Photons, are carriers of electromagnetic energy – they're their own field. The field though isn't really a fluid or medium – thinking about ripples moving across a pond won't help you. The field is just the distance over which the photon will travel. It's more about an area of opportunity for something to happen (e.g. in the event that something gets within range of the photon) rather than a big blobby mass actually hanging around in space. There's no such thing as "pure energy" (although the fundamental forces are probably the simplest forms of energy). Energy is an emergent property of a system (it is a function of how things in one part of a system are arranged with respect to another part of the system).