  The gravitational asymptotic safety program strives for a consistent and
predictive quantum theory of gravity based on a non-trivial ultraviolet fixed
point of the renormalization group (RG) flow. We investigate this scenario by
employing a novel functional renormalization group equation which takes the
causal structure of space-time into account and connects the RG flows for
Euclidean and Lorentzian signature by a Wick-rotation. Within the
Einstein-Hilbert approximation, the $\beta$-functions of both signatures
exhibit ultraviolet fixed points in agreement with asymptotic safety.
Surprisingly, the two fixed points have strikingly similar characteristics,
suggesting that Euclidean and Lorentzian quantum gravity belong to the same
universality class at high energies.
