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The full claim is "there are quantum fields", which is a different mathematical object from fields (or particles). To some it sounds unsatisfactory, to others i

The full claim is "there are quantum fields", which is a different mathematical object from fields (or particles). To some it sounds unsatisfactory, to others it sounds profound, and yet others are happy to just shut up and use the model to do calculation that just work.

danbruc 9y ago
The full claim is "there are quantum fields", which is a different mathematical object from fields (or particles). Sure, but the crucial points is, quantum fields are just mathematical tools, the universe is filled with particles, not with quantum fields stretching across all of spacetime. The fact that it is under some circumstances convenient to mathematically treat a large collection of particles as a quantum field does not make that quantum field a real thing, just as describing the traffic flow on roads with fluid dynamics as a mathematical modeling tool does not mean there actually exists a car field spanning across all the roads. [...] yet others are happy to just shut up and use the model to do calculation that just work. This certainly seems to works in many circumstances, but I think it is not really good enough to treat the point raised in this thread. When you are discussing whether an atom is mostly empty space, you have to be more careful. Just because your mathematical model uses objects that fill the entire atom does not necessarily mean that this is true for the actual atom, it could just be an artifact of your mathematical model.
- krastanov 9y ago
  I can not argue with you about that, because I consider it more a question for philosophers, not scientists. However, please also accept that for many people (me included) the model of quantum fields is much more real, and the model of point particles is the one that is just a mathematical illusion.
  - danbruc 9y ago
    There is no one-to-one correspondence between quantum fields and physical states due to gauge freedom and therefore quantum fields can not be real things. No experiment can yield the value of a quantum field at some point in space and time without fixing a gauge. We invented quantum fields to make locality obvious but this is not possible without making the description redundant and so we just declared that one physical state corresponds to an entire equivalence class of mathematical states. So I really don't think this is a matter of philosophy, they are not equivalent models.

danbruc 9y ago

The full claim is "there are quantum fields", which is a different mathematical object from fields (or particles). Sure, but the crucial points is, quantum fields are just mathematical tools, the universe is filled with particles, not with quantum fields stretching across all of spacetime. The fact that it is under some circumstances convenient to mathematically treat a large collection of particles as a quantum field does not make that quantum field a real thing, just as describing the traffic flow on roads with fluid dynamics as a mathematical modeling tool does not mean there actually exists a car field spanning across all the roads. [...] yet others are happy to just shut up and use the model to do calculation that just work. This certainly seems to works in many circumstances, but I think it is not really good enough to treat the point raised in this thread. When you are discussing whether an atom is mostly empty space, you have to be more careful. Just because your mathematical model uses objects that fill the entire atom does not necessarily mean that this is true for the actual atom, it could just be an artifact of your mathematical model.

krastanov 9y ago
I can not argue with you about that, because I consider it more a question for philosophers, not scientists. However, please also accept that for many people (me included) the model of quantum fields is much more real, and the model of point particles is the one that is just a mathematical illusion.
- danbruc 9y ago
  There is no one-to-one correspondence between quantum fields and physical states due to gauge freedom and therefore quantum fields can not be real things. No experiment can yield the value of a quantum field at some point in space and time without fixing a gauge. We invented quantum fields to make locality obvious but this is not possible without making the description redundant and so we just declared that one physical state corresponds to an entire equivalence class of mathematical states. So I really don't think this is a matter of philosophy, they are not equivalent models.