On the Theory of Surface Interactions

<p>I use the term <em>interaction </em>as an abstraction that applies, for example, to force-interactions, torque-interactions, and heat-transfers. </p> <p>If an interaction is a <em>surface-interaction </em>it can be characterized, under suitable conditions, by a <em>contactor.</em> In the case of force-interactions, torque-interactions, and heat-transfers, the contactor is the field of <em>stress-tensors, couplestress-tensors, </em>and<em> heatflux-vectors,</em> respectively. </p> <p>The first to prove, making suitable assumptions, the existence of such a contactor was Cauchy in 1823, and there has been a large literature on this subject since then. </p>