I recently read an article by Yasunori Nomura (https://arxiv.org/abs/1711.05263), in which he says that space-time is an emerging phenomenon. At the same time, space-time disappears when the holographic degrees of freedom are maximally entangled and when there is no entanglement at all.
Do I understand correctly that one can say:
Before the appearance of space-time, the universe was in a state in which the entanglement between the holographic degrees of freedom was zero.
Can there be a situation in quantum mechanics in which the subsystems are absolutely not entangled and suddenly, spontaneously, begin to entangle?