> "points on the screen" is the only reason we have to believe in particles
There are also the cloud chamber paths. But more generally, I would say most people's experiences correspond closer to stuff having well-defined localization which is more in the ballpark of particles than waves. Waves spread.
Also, this is not a matter of what is true, but rather what is plausible. A natural conclusion which works would be a good candidate to continue to pursue. My opposition to the paper cited was simply that it wants to argue that everything is a wave, something which seems to be an assumption not supported by evidence. That reality can be described that way is one thing, and a fine thing if it leads to interesting notions, but to say it must be a certain way is a completely different kind of claim.
> That doesn't seem reasonable to me. Particles exert forces on each other via gravity and electromagentism. I don't see how you're going to get a stable static vacuum configuration out of that without special pleading.
Particles in BM do not exert forces on each other. The wave function moves the particles about directly by specifying the velocity, not the acceleration. The forces are all in the wave function evolution (gravity is a bit of a mystery, but what else is new). Keep in mind there is a single wave function that represents the universe. It has a complicated dynamics which is where the forces are at work.
Maybe the short paper Are All Particles Identical [0] might help. It describes a version of BM in which all particles are identical and electron, quark, etc., are different states of a single particle type with the mass being incorporated into the wave function itself. Particles in that theory really are just points with nothing else intrinsic about them.
So the typical vacuum state might be just a small part of the story with a non-interacting sector. I don't know, but it certainly does not seem to rule out particles to me as being impossible.
> Just as if you want a completely accurate answer about what happens when you drop an apple you have to solve Einstein's field equations.
Yes, but if you present me with the solved system, I understand immediately what it is describing: a path through space-time of the apple. In a solved version is easy to see the correspondence.
This is not true of quantum wave stuff. It is true of BM. Relativity might mess with our intuition and be difficult to compute, but it is easy to understand how the elements correspond to our experience. That's the crucial difference.
Now, there is no reason to believe that the fundamental theory has to have that property. It might not. But it is extremely important than to be very clear about how the elements of the theory, the stuff it cares about saying what it state is, does correspond to our experience.
> Particles in BM do not exert forces on each other.
Right. That's part of the problem IMHO. Particles in BM don't really do anything except get pushed around by the wave function. So they don't really correspond to what most people intuitively think of when they think of particles: electrons and protons (and neutrons), which combine not only a spatial location but also mass and electric charge into a single unified package. BM particles only have the spatial location part.
> it is easy to understand how the elements correspond to our experience
I think it's not so hard to see how QM corresponds to our experience if you look at it the right way. Not quite as easy as relativity, but not nearly as hard as it's commonly made out to be.
Note that our experience is at odds with "reality" long before you get to QM. Even in a purely classical model of an atom, it's mostly empty space, and what we perceive as "solid" objects are really just electrons in outer shells trying to push each other out of the way.
There are also the cloud chamber paths. But more generally, I would say most people's experiences correspond closer to stuff having well-defined localization which is more in the ballpark of particles than waves. Waves spread.
Also, this is not a matter of what is true, but rather what is plausible. A natural conclusion which works would be a good candidate to continue to pursue. My opposition to the paper cited was simply that it wants to argue that everything is a wave, something which seems to be an assumption not supported by evidence. That reality can be described that way is one thing, and a fine thing if it leads to interesting notions, but to say it must be a certain way is a completely different kind of claim.
> That doesn't seem reasonable to me. Particles exert forces on each other via gravity and electromagentism. I don't see how you're going to get a stable static vacuum configuration out of that without special pleading.
Particles in BM do not exert forces on each other. The wave function moves the particles about directly by specifying the velocity, not the acceleration. The forces are all in the wave function evolution (gravity is a bit of a mystery, but what else is new). Keep in mind there is a single wave function that represents the universe. It has a complicated dynamics which is where the forces are at work.
Maybe the short paper Are All Particles Identical [0] might help. It describes a version of BM in which all particles are identical and electron, quark, etc., are different states of a single particle type with the mass being incorporated into the wave function itself. Particles in that theory really are just points with nothing else intrinsic about them.
So the typical vacuum state might be just a small part of the story with a non-interacting sector. I don't know, but it certainly does not seem to rule out particles to me as being impossible.
> Just as if you want a completely accurate answer about what happens when you drop an apple you have to solve Einstein's field equations.
Yes, but if you present me with the solved system, I understand immediately what it is describing: a path through space-time of the apple. In a solved version is easy to see the correspondence.
This is not true of quantum wave stuff. It is true of BM. Relativity might mess with our intuition and be difficult to compute, but it is easy to understand how the elements correspond to our experience. That's the crucial difference.
Now, there is no reason to believe that the fundamental theory has to have that property. It might not. But it is extremely important than to be very clear about how the elements of the theory, the stuff it cares about saying what it state is, does correspond to our experience.
[0]: https://arxiv.org/pdf/quant-ph/0405039.pdf