May 5, 2026 02:17 PM
https://aeon.co/essays/why-reality-is-mo...-particles
EXCERPTS: The advent of quantum field theory allowed us to ask what the field itself is made of. Here things get a little circular. The field is made of particles, which are excitations of the field. Within the framework of quantum field theory, fields and particles cannot be conceptually separated. To motivate this symbiosis, consider an analogy.
Imagine that, lying in my warm and luxurious bath, my gaze is dramatically drawn away from my navel as I realise I have inadvertently pulled out the plug. A swirling vortex forms in the water, centred on a filament of hole that connects the surface to the plughole. I am struck with an idea – Eureka! The hole is like a particle, and the circling water is like its field. I imagine shrinking to the size of a tiny fish, swimming under the surface. I would never have noticed the water before, but now I feel it through the circular pull of the vortex. Closer to the vortex, the pull would be stronger, suggesting some source at its centre. But no matter how close I get, within the water, the hole is always smaller.
This bathtub analogy sheds light on a long-running debate within physics and philosophy about whether it is particles or fields that are fundamental. One side has it that since we detect only particles, not fields, then the former are fundamental and the latter merely a mathematical abstraction. (I disagree with this, by the way: we detect fields all the time, such as when we move a compass with a magnet, and many experiments that purport to detect particles do so by detecting their fields.) The other side counters that particles emerge from fields, so the latter must be more fundamental.
I admit I never really understood the debate. Particles and fields are inseparable: in the bath, the whirlpool-like hole connecting the surface to the drain exists only by reference to the water, but the water can circulate only by virtue of the hole. Trying to establish which is more fundamental seems to make about as much sense as arguing over what defines a room, with one side arguing it is the walls, and the other arguing it is the space between them.
[...] Once we get to our finished picture with atoms smoothed away, there is no essential difference between the mathematical descriptions of elementary and emergent particles. We just happen to know that the latter would also admit a description in terms of atoms, should we choose to make it.
Despite this, it is often suggested that elementary particles are ‘real’ whereas emergent particles are not. Emergent particles are sometimes called ‘quasiparticles’ to emphasise this reduced status. The reasoning is that phonons, say, are just a simpler description of the real atomic motion.
[...] I would raise several objections here. First, emergent things clearly exist. For example, owls exist. They are real. But they are also emergent, as they admit a description in terms of atoms. Second, as mentioned earlier, the mathematical description of emergent and elementary particles is identical. If the mathematics says they are the same, on what basis can we claim they are different? The answer cannot depend upon the atoms since they were already smoothed away to reach the field description. And third, our evidence of emergent particles is as direct as that of elementary particles.
[...] A weaker claim could be that emergent particles are real but not fundamental. But that would be to invoke the meaning of fundamental in which only one set of things ever holds that status. As we established, that claim cannot be made scientifically. The scientific claim must be that emergent and elementary particles hold precisely the same ontological status. In other words, they are just as real as one another... (MORE - missing details)
EXCERPTS: The advent of quantum field theory allowed us to ask what the field itself is made of. Here things get a little circular. The field is made of particles, which are excitations of the field. Within the framework of quantum field theory, fields and particles cannot be conceptually separated. To motivate this symbiosis, consider an analogy.
Imagine that, lying in my warm and luxurious bath, my gaze is dramatically drawn away from my navel as I realise I have inadvertently pulled out the plug. A swirling vortex forms in the water, centred on a filament of hole that connects the surface to the plughole. I am struck with an idea – Eureka! The hole is like a particle, and the circling water is like its field. I imagine shrinking to the size of a tiny fish, swimming under the surface. I would never have noticed the water before, but now I feel it through the circular pull of the vortex. Closer to the vortex, the pull would be stronger, suggesting some source at its centre. But no matter how close I get, within the water, the hole is always smaller.
This bathtub analogy sheds light on a long-running debate within physics and philosophy about whether it is particles or fields that are fundamental. One side has it that since we detect only particles, not fields, then the former are fundamental and the latter merely a mathematical abstraction. (I disagree with this, by the way: we detect fields all the time, such as when we move a compass with a magnet, and many experiments that purport to detect particles do so by detecting their fields.) The other side counters that particles emerge from fields, so the latter must be more fundamental.
I admit I never really understood the debate. Particles and fields are inseparable: in the bath, the whirlpool-like hole connecting the surface to the drain exists only by reference to the water, but the water can circulate only by virtue of the hole. Trying to establish which is more fundamental seems to make about as much sense as arguing over what defines a room, with one side arguing it is the walls, and the other arguing it is the space between them.
[...] Once we get to our finished picture with atoms smoothed away, there is no essential difference between the mathematical descriptions of elementary and emergent particles. We just happen to know that the latter would also admit a description in terms of atoms, should we choose to make it.
Despite this, it is often suggested that elementary particles are ‘real’ whereas emergent particles are not. Emergent particles are sometimes called ‘quasiparticles’ to emphasise this reduced status. The reasoning is that phonons, say, are just a simpler description of the real atomic motion.
[...] I would raise several objections here. First, emergent things clearly exist. For example, owls exist. They are real. But they are also emergent, as they admit a description in terms of atoms. Second, as mentioned earlier, the mathematical description of emergent and elementary particles is identical. If the mathematics says they are the same, on what basis can we claim they are different? The answer cannot depend upon the atoms since they were already smoothed away to reach the field description. And third, our evidence of emergent particles is as direct as that of elementary particles.
[...] A weaker claim could be that emergent particles are real but not fundamental. But that would be to invoke the meaning of fundamental in which only one set of things ever holds that status. As we established, that claim cannot be made scientifically. The scientific claim must be that emergent and elementary particles hold precisely the same ontological status. In other words, they are just as real as one another... (MORE - missing details)