Semiclassical world is one of infinite many cloneworlds in common spacetime

Abstract

We consider $N$ clones of the quantized world, interacting with each other via quantum gravity, coupled by the downscaled Newton constant $G/N$. In the limit $N\rightarrow\infty$, we obtain the semiclassical Einstein equation for every single cloneworld. In the non-relativistic limit, De Filippo had already obtained the semiclassical Schr\"odinger-Newton equation, we present an alternative elementary proof. In the general relativistic case we complete the semi-finished derivation of Hartle and Horowitz. We compare our simple correlated cloneworlds with Stamp's more complicated proposal of correlated worldlines and show why they differ despite the conceptual similarity.