In particle physics, we try to understand reality by looking for smaller and smaller building blocks. But what if that has been the wrong philosophy all along? In standard use, the S-matrix can be calculated if you understand the forces in the interaction region – for example, in the nucleus of an atom. But what if you don’t know those internal interaction forces? Heisenberg sought a way to ignore that internal structure and, rather, treat the S-matrix as fundamental. The S-matrix was to become the physics of the interaction, rather than an emergent property of more fundamental, internal physics. Heisenberg’s made some progress in the 40s, but the approach came…