The principle of causal neutrality
- Ding Jia (Perimeter Institute, Waterloo, Canada)
Abstract
The "principle of causal neutrality", motivated by quantum gravity, says that fundamental concepts of physics should be defined without assuming a definite spacetime causal structure.
Forced by this principle, I propose a generalization of standard AQFT using the free product of star-algebras. The state, rather than the algebra, encodes the spacetime causal structure, which can be quantum. Similarly, I propose a generalization of the notion of entanglement so that the parties sharing the correlation may have quantum indefinite causal structure.
As a payoff of the generalizations, I derive an ultraviolet regularization mechanism coming from causal structure fluctuations. This suggests a new condition to supersede the Hadamard condition to characterize the UV structure of physical states.
