AFAIK the particles vs fields discussion is not the same as temperature vs fields. At the risk of straying into quantum info territory: - given all possible i

AFAIK the particles vs fields discussion is not the same as temperature vs fields. At the risk of straying into quantum info territory: - given all possible information about a collection of particles, you could compute the temperature. However, knowing the temperature doesn't allow you to determine info about particles uniquely (you can write down a density matrix, and not assign a pure state). - the above doesn't hold for the case of particles and fields. Given a set of field frequencies and amplitudes, you could describe the positions of particles and probabilities of observing them. Given positions and probabilities of observing particles, you could compute the frequencies and amplitudes of the associated field. We can describe any given set of particles (however big or small, however fast or slow) in terms of fields, and vice versa. I like this comment : When I studied quantum mechanics, my professor advised that I avoid the question "which is more fundamental?" and replace it with "which is more useful?". From this stackoverflow link (http://physics.stackexchange.com/questions/122570/which-is-more-fundamental-fields-or-particles/122574#122574 http://physics.stackexchange.com/questions/122570/which-is-m...) My QFT knowledge is rusty, so please correct me if I'm wrong.