The arrow of time in operational formulations of quantum theory

The operational formulations of quantum theory are drastically time oriented. However, to the best of our knowledge, microscopic physics is time-symmetric. We address this tension by showing that the asymmetry of the operational formulations does not reflect a fundamental time-orientation of physics. Instead, it stems from built-in assumptions about the users of the theory. In particular, these formalisms are designed for predicting the future based on information about the past, and the main mathematical objects contain implicit assumption about the past, but not about the future. The main asymmetry in quantum theory is the difference between knowns and unknowns.

Automated summary

The operational formulations of quantum theory show time orientation, while microscopic physics is time-symmetric. This tension is not a reflection of a fundamental time orientation in physics, but stems from assumptions about the users of the theory. These formalisms are designed for predicting the future based on information about the past, with main mathematical objects containing implicit assumptions about the past rather than the future. The main asymmetry in quantum theory lies in the difference between knowns and unknowns.