On the Bondgraphic Power Postulate and its Role
in Interpreting the 1905 and 1915 Relativity Theories


Since their official birth on April 24, 1959, bondgraphs evolved to become one of the most effective and most elegant tools for modeling system dynamics. The unifying attitude of bondgraphs, or BGs for short, towards systems, enables model builders to connect system components from different physical domains using the same set of bondgraphic elements. It was this unifying attitude that furnished the impetus for this work that investigates the possibility of applying BGs to Einstein's standard theories of relativity, thus extending the BG approach of modeling to relativistic dynamics. To this end, a new formulation of the bondgraphic power postulate that is built using four-vector efforts and flows is developed, with a brief introduction to tensor calculus. Then special relativistic particle-mechanics and electro-dynamics (via a one particle system) are investigated, and the bondgraphic interpretations for both are also provided. Finally, we provide Einstein's gravitational field equations, a bondgraphic interpretation of them, and the energetic problems in general relativity with suggestions to solutions.