On the interpretation of quantum theory as games between physicists and nature played in Minkowski spacetime

Abstract

In 2019, we introduced games in Minkowski spacetime as a generalization of game theory to special relativity that subsumes games in normal form (spacelike separation) and games in extensive form (timelike separation). Many concepts including Nash equilibria naturally extend to spacetime games. We also emphasized the importance of these games to model quantum experiments such as Bell experiments and more generally any adaptive measurements. Subsequent work suggested to formalize a special case of such games in terms of strategy presheaves. In the case that measurements have a unique causal bridge and if a natural cover is taken, we show that the two frameworks are isomorphic to each other and provide complementary perspectives. Spacetime games provide a visual and intuitive framework that also captures the distinction between joint experiments and either-or experiments, so that they are rich enough in their causal structure to imply a natural cover for the corresponding causal contextuality scenario. Based on this observation, we suggest to define the strategy presheaf directly based on the pure strategies (and restrictions thereof) of the spacetime game, and we show that the sheaf property obtains for the games at hand. The argument is rather simple and similar to event sheaves for the flat case. Finally, we explain how, in the other direction, the failure of the sheaf property on strategy distribution presheaves is consistent with our previous argument that Nash game theory is not compatible with quantum physics. This shows that the insights of the two frameworks, taken together, can contribute positively to the advancement of the field of quantum foundations.