While we began to understand how to construct renormalizable theories for the weak intractions, the strong interactions were still shrouded in mystery. They looked much less controllable. Investigators did learn how to cause various particles to collide with each other with increasing collision energies, using new and ever more powerful acceleration machines, resulting in a much better understanding of the curious internal structure of the hadrons. What was immediately obvious was that the list of resonances became longer and longer. A resonance could best be described as a particle that in all respects resembles one of the particles of Table 1, only its mass is bigger and often its spin is greater. The resonances came in series, with the heavier ones often having the highest spin. There are baryonic and mesonic resonances. Without changing the total of the quantum numbers S (strangeness) and I3 (isospin), these resonances can decay into lighter particles within some 10−23 seconds.

It was difficult to understand why the hadrons behaved in this way. But, without attempting to answer such questions, Gabriele Veneziano discovered a simple mathematical formula that represented, in a particularly elegant way, the effects of all these resonances when particles collide. The remarkable thing about his formula was that in it the effects of the strong force were described very realistically (that is, relatively well in agreement with what was known from experiments), whereas no single existing theory could explain the formula. Not yet. Veneziano's formula would playa very important role, and I will return to it later.