Nobel lecture: Asymptotic freedom: From paradox to paradigm

The idea that Quarks that are born free are confined and can't be pulled apart was once considered a paradox. The emerging theory for strong interactions, Quantum Chromo Dynamics (QCD) predicts the existence of gluons, which together with quarks can be seen indirectly as jets from hard scattering reactions between particles. Quantum Chromo Dynamics predicts that the forces between quarks are feeble for small separations but are powerful far away, which explains confinement. Many experiments have confirmed this property of the strong interaction.