Nontrivial bookkeeping: a mechanical perspective

Although economic practice is measured by bookkeeping, economic theory neglects its role. We want to bridge this gap. We analyze the structure of bookkeeping from a mechanical viewpoint and compare money with momentum. Bookkeeping and income statements translate to the physicist vocabulary of momentum, energy and force. Financial transactions become Feynman-graphs. Although the realization principle enforces conservation of momentum in each currency, no conservation of energy is implemented by bookkeeping. We discuss the transaction axiomatics of bookkeeping from this physical viewpoint.