This paper presents a structural mechanism that unifies blood compatibility and matter–antimatter asymmetry under a single operator. Both systems begin with two modes that share nearly identical properties and differ by a microscopic marker asymmetry. The analysis shows that each system evaluates this asymmetry through a threshold operator that amplifies a small structural difference into macroscopic mode survival. The paper identifies structural tension as the primitive evaluated by the operator. The universe preserves the mode with lower structural tension and eliminates the mode with higher structural tension through destructive interaction. Blood compatibility provides the observable model system. Matter–antimatter interaction expresses the same structural rule at a different scale. The survival of matter is the result of this universal structural mechanism.
Brian Rieckmann (Sat,) studied this question.