[MisterMashable]

Quantum Field Theory is really just ordinary Quantum Mechanics. It is necessary to use fields instead of "wave equations" because the number of particles can vary when the energy of a system exceeds a certain threshhold. (e.g. a single photon having an energy equal to or higher than the E=mc^2 energy of two electrons can transmute into an electron-positron pair. 1 particle transforms into 2. This is very common in high energy processes.)

Quantum fields are REAL because certain phenomena like solitons, vortices, monopoles and quark confinement can only be understood properly in the full field context. Quantum field theory cannot describe these phenomena in terms of Feynman diagrams. Feynmann diagrams and scattering cross sections/lifetimes were once considered fundamental and fields were believed to be a tool to derive them. Physicists now understand (the competent ones) that Fields are more fundamental than the diagrams. The Fields are also real in the sense that the do much more than just represent particle states, field symmetries are fundamental symmetries of nature, e.g. the strong force has SU(3) symmetry, electroweak SU(2)xU(1) etc.

Steven Weinberg gives a very strong argument for the necessity of fields in his vol. 1 QFT book. It's very technical but a brief summary is... QM + relativity + cluster decomposition principal (which more or less says the results of distant experiments should be unrelated) --> fields

[danbruc]

Now I have to dig out a statement by Nima Arkani-Hamed where he says something like "[...] should bother you if you believed that fields are real." - I of course forgot the most important part but I still remember in which lecture series he said that. If my memories does not mislead me, he was really arguing that you should not think of fields as real things for very concrete reasons. Trying to find it.

[danbruc]

This took way longer than I imagined. I won't repeat the argument here in detail but it essentially boils down to the argument that fields theories are just an effective description of long distance behavior ignoring what is really going on at short distances, that fields are just a convenient tool to make locality manifest and that field theories contain a lot of redundancies due to this.

The statement I was referring to comes 28 minutes into the lecture but you probably have to watch everything up to that point for the full context.

So after watching this again the answer to my question seems pretty clear - fields are not real things. I am still left a bit confused because you very often read and hear that fields are real things and actually more often then the opposite.

https://m.youtube.com/watch?v=tnA7bh7dTqY

[T-A]

http://arxiv.org/abs/1204.4616 :)

[danbruc]

Ohhh no! Just when I thought I got the answer. Just skimmed it and I draw some hope from the fact that the author uses the unconfirmed Unruh effect and wave function collapse, which is as far as I know not a thing because it is not unitary, to explain the double slit experiment. So maybe it is the author who is confused and not the others he is complaining about and I won't have to change my mind once again but I will have to read it way more carefully before drawing any conclusions.