Why are gluons needed to hold quarks together. If the 3 are in a line, equally spaced, with the oddball charge in the middle, they will attract quite strongly.
+2. -1. +2
If these charges are equally spaced, the attraction of the middle one in stronger than the repulsion of the outer two.
It's not necessarily a questions of "need". Physicists are just measuring what protons ARE. Whether or not gluons and the strong force are necessary to form an object that looks like a proton is a separate point from what protons actually look like in our universe.
To your point on if such an arrangement would be possible or not ignoring the strong force, it would not. The "net-charge" viewed from the +2 quark would be repulsive, resulting in an unstable arrangement of matter, even if you could construct it in an equilibrium state it would be the unstable kind.
Good point! But it's also an unstable system: the -1 will get attracted to one of the +2 charges and (from a distance) look like a +1, and the other charge will fly off to infinity.
I guess we could design a bunch of picometer-scale scaffolds that hold everything in place and this might work, but that doesn't seem to be the way nature put things.
Sure, but what if they're orbiting the center charge at relativistic speeds? Now they also create a magnetic field. My guess is that somehow it ends up being dynamically stable. Also that the strong force holding the nucleus together is actually mostly magnetism.
I would also posit that just maybe there is such thing as an electrostatic black hole. When matter is accelerated gravitationally to speed c, you reach an event horizon. Same should happen if the acceleration is due to charges, but will happen at a scale similar to the size of baryons. I'd say there is a lot of room for some theoretical developments in this area.
> Also that the strong force holding the nucleus together is actually mostly magnetism.
If that were the case, you would expect protons to tear apart in the presence of strong electric fields. The fact that this seems impossible suggests pretty strongly
+2. -1. +2
If these charges are equally spaced, the attraction of the middle one in stronger than the repulsion of the outer two.