• Threat arises from intention; risk does not.
• Threat imports specific consequence; risk is based only upon measurable loss. Loss can be from an attack or it can be inadvertent.
• Threat requires intention; risk does not.
• Threat requires identification; risk does not.
• Physicists sometimes forget that their theories, their models of nature, are simply mathematical constructs that predict the results observed when we do something to the real world. The models are not the real world; they are simply tools to predict observations.
• Current theories such as the quantum theory are based on assumptions that form the basis for mathematical models. The results may be rigorous mathematical models that are true to the initial assumptions, but they are only as good as those assumptions. My recollection of quantum theory is that we always assume a linear vector space, a Hilbert space. The model is therefore valid only for that type of space.
• Causality and linearity seem to be basic assumptions in all our theories, but they also may be self-contradictory assumptions.