Researchers from the Kavli Institute for the Physics and Mathematics of the Universe have been conducting a study of black holes that could’ve formed in the early universe. These so-called primordial black holes are believed to have formed before stars and galaxies were born. Primordial black holes could account for all or part of dark matter and be responsible for some of the observed gravitational wave signals and supermassive black holes found in the center of our galaxy and others.
The researchers also theorize the primordial black holes could play a role in the synthesis of heavy elements when they collide with neutron stars and destroy them, releasing neutron-rich material. The most interesting theory is that dark matter is composed of primordial black holes. Researchers looked at the early universe for clues about primordial black holes during the study.
They believe the early universe was so dense that any positive density fluctuation of more than 50 percent would create a black hole. A number of processes in the early universe could have created the right conditions for black holes to form. Another exciting prospect put forward by the research team is the possibility that primordial black holes could form from “baby universes” created during inflation. Inflation is a period of rapid expansion believed to be responsible for seeding galaxies and clusters of galaxies we observe today.
During inflation, baby universes could branch off from our universe, creating a baby or daughter universe that would eventually collapse. The large amount of energy released in the small-volume causes a black hole to form. According to Einstein’s theory of gravity, the universes can exist in a state that appears different to an observer on the inside and the outside. Observers on the inside would see an expanding universe, while observers on the outside (such as us) would see it as a black hole.
We would see big and small baby universes as primordial black holes hiding the underlying structure of multiple universes behind the black hole’s event horizon. In the paper, the researchers described a scenario for primordial black hole formation and showed that black holes from the “multiverse” could be found using the Hyper Suprime-Cam on the Subaru Telescope in Hawaii.