Asymptotic Freedom

Nuclei are very strongly bound aggregates of protons and neutrons. The nucleons in turn, we now believe, are extremely strongly bound aggregates of quarks: so strongly bound that we have never seen a free quark. The nuclear force is not a constant, however, but varies with the distance between the quarks. The dynamics of the vacuum enhance the force at large distances, while at short distances the interaction grows weaker. The notion that the force between quarks becomes vanishingly small as the quarks come close together, or, equivalently, that the quarks become free particles at very large energies, is called asymptotic freedom. I was very fortunate to be able to contribute to the discovery of asymptotic freedom, so I shall start with a few historical remarks, describing my own personal road to this discovery, and then discuss the current status and significance of asymptotic freedom.

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