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27. Natural Reality / B. Modern Physics / 3. Chromodynamics / a. Chromodynamics

[general principles of the strong nuclear force]

5 ideas
The strong force pulls, but also pushes apart if nucleons get too close together [Inwagen]
     Full Idea: The strong force doesn't always pull nucleons together, but pushes them apart if they get too close.
     From: Peter van Inwagen (Material Beings [1990], 07)
     A reaction: Philosophers tend to learn their physics from other philosophers. But that's because philosophers are brilliant at picking out the interesting parts of physics, and skipping the boring stuff.
The strong force is repulsive at short distances, strong at medium, and fades at long [New Sci.]
     Full Idea: Experiments show that the nuclear binding force does not follow the inverse square law, but is repulsive at the shortest distances, then attractive, then fades away rapidly as distance increases further.
     From: New Scientist writers (Why the Universe Exists [2017], 02)
     A reaction: So how does it know when to be strong? Magnetism doesn't vary according to distance, and light obeys the inverse square law, because everything is decided at the output. - See 21151 for an explanation. It interacts after departure.
The strong force binds quarks tight, and the nucleus more weakly [New Sci.]
     Full Idea: The strong force holds quarks together within protons and neutrons, and residual effects of the strong force bind protons (whch repel one another) and neutrons together in nuclei.
     From: New Scientist writers (Why the Universe Exists [2017], 02)
     A reaction: So the force is much stronger between quarks (which can't escape), and only 'residual' in the nucleus, which must be why smashing nuclei open is fairly easy, but smashin protons open needs higher energies.
Gluons, the particles carrying the strong force, interact because of their colour charge [New Sci.]
     Full Idea: In QCD the particles that carry the strong force are called gluons. ...Gluons carry their own colour charges, so they can interact with each other (unlike photons) via the strong nuclear force (which limits the range of the force).
     From: New Scientist writers (Why the Universe Exists [2017], 02)
     A reaction: So the force varies in strength with distance because the degree of separation among the spreading gluons varies? The force has one range, which is squashed when close, effective at medium, and loses touch with distance?
Colour charge is positive or negative, and also has red, green or blue direction [Hesketh]
     Full Idea: Colour charge is 'three-dimensional'. As well as the charge having a positive or negative sign, it can also have a direction, and for convenience these three different directions (pointing like a weather vane) are labelled 'red', 'green' and 'blue'.
     From: Gavin Hesketh (The Particle Zoo [2016], 04)