There was a way out! However, it originates in quite a different branch of theoretical physics, to wit the physics of metals at very low temperatures. At very low temperatures, ‘quantum phenomena’ can lead to quite remarkable effects. To describe these effects one uses quantized field theories, exactly the same as the ones employed in elementary particle physics. The physics of elementary particles has nothing to do with the physics of low temperatures, but the mathematics is very very similar!

The ‘field’ in some material that becomes important at low temperatures could be the field describing how atoms there oscillate about their equilibrium points, or else the field that describes electrons in this material. At very low temperatures we have to deal with the ‘quanta’ of these fields. For instance, the ‘phonon’ is the quantum of sound. Its behavior resembles that of the photon, the quantum of light, except that the numbers are very different: phonons travel with the speed of sound, hundreds or perhaps thousands of meters per second; the photon travels with light velocity, which is 300000kilometers/second, nearly one million times faster! The elementary particles we are interested in usually have velocities close to that of light.

One of the more spectacular ‘quantum phenomena’ that can take place in strongly cooled metals is called superconductivity, which is the fact that the resistance of such a material to electrical currents vanishes completely.