Primordial Black Holes: Could Spacetime Form BHs?

[PaulMurphy]

Could the primordial black holes that seeded the first galaxies have been formed from spacetime that never expanded below the critical threshold for black hole formation? If quantum jitters caused the variation in densities seen in the cosmic background radiation, could islands of higher density have been caught above the critical black hole forming density just as the rest of spacetime expanded enough to be too rarified for black hole formation?

 

[qraal]

Could the primordial black holes that seeded the first galaxies have been formed from spacetime that never expanded below the critical threshold for black hole formation? If quantum jitters caused the variation in densities seen in the cosmic background radiation, could islands of higher density have been caught above the critical black hole forming density just as the rest of spacetime expanded enough to be too rarified for black hole formation?

The idea that PBHs seeded the galaxies has been around for a long time, but it's still speculative and hard to derive an observational test for. As for the scenario you suggest that's exactly how PBHs were believed to have formed. Alternatively black holes might survive a Big Crunch/Bounce and come from a previous cosmic cycle.