[William Tell]

Physicist said: The flux tube thus acts like a spring. If you pull the quarks far enough apart, you will put enough energy into the flux tube to create a new quark-antiquark pair, which will "screen" the separating quarks from each other (i.e., snap the long flux tube into two short ones).

Thanks. I get it. I think.

Physicist said: In other words, the force is self-coupled. The result is that the force is proportional to distance."

I don't get it. Do you have a simpler way to explain what the term "self-coupled" means in this context. What are the alternatives to being "self-coupled"? Did you mean to say that the force is constant with distance or proportional to distance. The former was the case I thought applied. Is the strong force proportional to distance?

[Physicist]

I don't get it. Do you have a simpler way to explain what the term "self-coupled" means in this context. What are the alternatives to being "self-coupled"? Did you mean to say that the force is constant with distance or proportional to distance. The former was the case I thought applied. Is the strong force proportional to distance?

The strong force is proportional to distance, not constant with distance.

By "self-coupled", I mean that the strong force interacts via the strong force. Imagine what optics would be like, if every photon carried an electromagnetic charge.