"Furthermore, such particles should be able to propagate continuously through spacetime and so the object that describes them should "operate" at each point in spacetime. Hence we should consider a field of operators, a so called
quantum field?!"
From what I understand, combining special relativity with quantum mechanics requires quantum field theory (QFT). Why fields? I can see that for quantities already described by classical fields, suc...
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Quantum fields should be continuous.
Particle decay cannot be predicted on an individual particle but a collection of unstable particles can be predicted involving a time scale.
Virtual disturbances also do not violate a certain time limit related to their energy. By keeping their time to small enough increments they are allowed to exist.
All this demonstrates time is just as effective at the quantum scale. If time was just an emergent property why would quantum phenomenon obey time? Gravity must operate at the quantum scale, there are microscopic black holes and the event horizon is subatomic.