When two virtual particles appear through pair creation, does their brief presence present a gravitational influence on the surrounding universe? If so, then after they self annihilate, does that gravitational influence remain or disappear? The external gravitational influence of black holes is often attributed to the mass that was present before collapsing to the singularity... does the gravitational influence of virtual particles remain in a similar way after they are "gone"? And if so, how much "extra" gravitational influence in the universe might be attributed to this vs dark matter? It is usually posed that observations imply missing mass for the gravitation observed, but might it just as well be "too much" gravity not associated with existent matter?