important structural ingredient of the deep structure of our quantum vacuum is a network of microscopic wormholes. In contrast to e.g. [string theory]{} and [loop quantum gravity]{} (LQG), which both employ the quantum laws more or less unaltered all the way down to the remote [Planck scale]{}, we regard this as an at least debatable assumption. We rather view the holographic hypothesis as a means to understand how both quantum theory and gravitation do emerge as derived and secondary theories from a more fundamental theory living on a more microscopic scale. A central role in this enterprise is played by an analysis of the microscopic structure of the [quantum vacuum]{} which leads to the key concept of [wormhole spaces]{}.

This important conceptual structure makes it possible to understand the holographic aspects of quantum gravity, on the one hand, and the (non-local) entanglement phenomena pervading ordinary quantum physics, on the other hand, in a relatively natural way. Furthermore we think that there exist links to the old ideas of e.g. Sakharov and Zeldovich, dubbed [induced gravity]{} (see for example [@Sa; @1],[@Sa; @2],[@Z1],[@J1]).

Some words are in order regarding the relation of our investigation to the analysis of BH entropy in, say, 