The early universe contained far fewer miniature black holes than previously thought, making the origins of our cosmos's missing matter an even greater mystery, a new study has suggested.
But even though the hypothesis is popular, it has one big problem: we've yet to directly observe any primordial black holes. Now, a new study has offered a possible explanation as to why they didn't form, throwing open cosmology's dark matter problem to wider speculation. "Many researchers feel they are a strong candidate for dark matter, but there would need to be plenty of them to satisfy that theory," lead author Jason Kristiano, a graduate student in theoretical physics at the University of Tokyo, said in a statement."They are interesting for other reasons too, as since the recent innovation of gravitational wave astronomy, there have been discoveries of binary black hole mergers, which can be explained if PBHs exist in large numbers.
As the universe grew, ordinary matter, which interacts with light, congealed around clumps of invisible dark matter to create the first galaxies, connected together by a vast cosmic web. Nowadays, cosmologists think that ordinary matter, dark matter and dark energy make up about 5%, 25% and 70% of the universe’s composition, respectively.
Some physicists think there's a possibility they haven't discovered the vast numbers of primordial black holes necessary to account for dark matter simply because they've yet to learn how to detect them.