They exist in a superposition of positions :) The way I like to understand it (possibly false analogy but bear with it) is that fundamentally, at the smallest scales, particle forces are probabilistically determined.
Force vectors thus randomly (probabilitically) pop in and out of existence through worm-hole-like portals as per the laws of quantum mechanics and these force vectors are what decay into particles and vice versa.
So depending on the conditions, these neutrons coud behave like quantum force-vector particles and vice versa.
Not an expert, but there are indeed theories that try to do away with these apparent probabilities and reinstate determinism by moving the unfulfilled probability counterparts to the visible collapsed ones into parallel universes. The wavefunction collapse is just an illusion in those theories. It's closer to philosophy than science, even though it's based on actual equations. As it likely cannot be proven, it mostly makes for some interesting science-inspired fiction books. I think people like Brian Greene wrote about this, but I haven't read these books in years so I'm not sure.
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Force vectors thus randomly (probabilitically) pop in and out of existence
Or another way to think if it is: God is a staunch free-will advocate :)
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