““One can take the colour-electric field as the fundamental entity, and then try to understand the picture of a string stretched between the quarks as a consequence of space having properties that make it something like an electric version of a superconductor. This is the route taken by those physicists who work on QCD. For them, the key problem is to understand why empty space has properties that make it behave in certain circumstances like a superconductor. This is not as crazy as it sounds. We understand that in quantum theory space must be seen to be full of oscillating random fields, as discussed in Chapter 6. So we may imagine that these vaccum fluctuations sometimes behave like the atoms in a metal in a way that leads to large-scale effects like superconsuctivity.””
