# Theoretical implications of multidimensional Time [duplicate]

1. While the idea of extra spatial dimensions has been around for quite a while now, is there a possibility or any theory which proposes extra time dimensions?

2. If so, what could be theoretical implications of multidimensional time on existing theories like relativity or QM?

3. Would they work just fine?

## marked as duplicate by John Rennie, ACuriousMind♦, Qmechanic♦Jan 20 '16 at 13:49

• A hypersurface of dimension $n-1$ is required to solve matter fields equations on a spacetime, but obviously such a hypersurface will not be purely spacelike in the case of an ultrahyperbolic spacetime. Hence you cannot predict events given informations on the current time.