How have black holes been proposed as possible sites for baby-universe formation?

In the context of cosmology and the multiverse, the idea that black holes could serve as sites for the formation of "baby universes" is a theoretical concept often linked to the nature of singularities.

While science fiction frequently depicts black holes as portals to other dimensions, some scientific theories explore a connection between the interior of a black hole and the big bang. Because a black hole’s singularity represents a point of extreme density and the distortion of space-time, some researchers have proposed that the birth of our own universe from a singularity might be mirrored by the processes occurring within black holes elsewhere. In this view, the intense gravitational collapse within a black hole could potentially trigger the expansion of a new, separate "baby" universe.1

However, it is important to note that these ideas remain speculative. Because black holes are inaccessible and their interiors are hidden behind the event horizon, there is currently no known way to test or empirically prove these theories.1