Question for physics types: in a hydrogen atom, each quark feels a force from the other two quarks. But if the force really is constant over all distances, would it not feel an equal, or even greater force, from all the other quarks in the entire universe? If there was any imbalance, even one more quark on one side of the Hydrogen atom than the other, wouldn't the quark be pulled toward that?
Or does the strong force go back to zero at distances say larger than an atom?
The charge of the strong force is called color, and outside particles like protons the total color charge seen from the outside is zero.
It stays zero because of color confinement - at some point, it's less energetic to create color-anticolor pair instead of allowing color imbalance.
It's only constant force for quarks in isolation. A good mental model is that between the oppositely charged particles, a string of gluons forms and pulls them together with constant force. The resulting composite particle no longer has a color charge, so it does not interact as much with other particles through the strong force.
Of course there are also residual forces from a color-neutral bound state to quarks which are a bit further away, but those are not nearly as strong. They are for instance responsible for holding nuclei together.
The important property of the strong force here is that it interacts with itself. The field of two quarks together is not the sum of their individual fields, because the force-carrying gluons are also color charged and thus interact with each other.
I had the same thought. Perhaps the bound quarks are never far enough apart for the strong force to be constant?
My understanding is that if you do manage to pull two quarks apart the energy of separation is eventually enough to form two new quarks, thus pairing them up again.
My question is whether this pair production happens before or after the strong force reaches the region where it is constant?
I'm not a professional physicist, so take this with a grain of salt. But first of all: the same question could be asked about "everyday" electric forces, and the answer is simple: positive and negative particles bond together and neutralize each other; their fields get overlapped. All the remaining force due to small physical distance(?) or quantum jiggle(?) is very small residues. (But it is enough to beget molecular dynamics.)
I think (guess?) that the strong force does the same, in the sense that there is a "neutralizing tendency", anyway, but the mechanism is different. Protons and neutrons, and pions too, are neutral when you watch them from far away. (But not so, when you are trying to explain why atomic nuclei are formed, protons and neutrons _like_ to clump together.)
The difference between a photon field and a gluon field is that gluons are attracted to each others in a way that I, as a non-nuclear-physicist don't quite understand (as the symmetry between them is not something I've actually studied); but as photons form "beams" (you can think of them in a linear algebra sense of vectors, almost!) that propagate in a very geometrically uniform way, gluons, being attracted to each others, form "tubes", which behave, as any self-interacting system would, in a very dynamic way.
Imagine a cellular simulation (like the Game of Life, but more... floating point instead of of integers & squares) where each quark sends gluons but they tend to clump together and form tubes? These tubes can't be super long, because quantum physics and the universe works in a way that energy gets minimized, and anything that could happen to make that happen, tends to happen. That means that if there's enough energy stored in the tube, it becomes "cheaper" for the universe to sever that connection and instead, produce new, separate particles that have their own, internal "tubes". That means that no long "tubes" of gluons are allowed in the universe, and thus, the strong force of the Strong Force is contained.
So the mechanism seems to be really super different from "overlapping +/- fields", in a sense, but the result is the same: no forces (albeit small residues) seen from afar.
As I understood, it's constant only after some distance, meaning that the force to its very close quarks is still much stronger than the constant force from the rest of the universe.
After reading a bit more I think I got it all backwards. The force increases with distance, up to a constant, but it seems this is only applicable to already bound quarks, so there's no strong force from rest of the universe.
But that's my point. If the strength of the force is constant, independent of distance, then the farther away quarks contribute the same as the nearer quarks. In other words, distance doesn't matter, whether something's farther away or closer has no bearing on the strength of the force.
Or does the strong force go back to zero at distances say larger than an atom?