Quantum Gravity Seminar: Fay Dowker

Speaker: Fay Dowker (Imperial Coll.)

Spacetime coordinates: Wed @ 13:30, Auditorium A

Zoom Link: https://ucph-ku.zoom.us/j/9295289933?omn=67282578176

Title: Quantum Causality and the Path Integral

Abstract: I will argue that Bell's condition of "local causality'' that results in the Bell inequalities for correlations between experimental results can usefully be divided into two separate conditions of "locality" and "relativistic causality". The former means an effect must propagate locally through spacetime and the latter means that an effect must be in the future lightcone of a cause. I will argue that we can maintain the position that relativistic causality holds in quantum theory if we give up locality. But "relativistic causality" by itself then becomes a very weak condition. It cannot explain why correlations allowed by quantum mechanics are bound by the T'sirelson inequalities. I will introduce a causality condition on generalised path integral quantum theory that does the job of resulting in the T'sirelson inequalities. The condition requires a background causal structure however, so the question of how and why and if quantum gravity is causal remains wide open.