Exploding Primordial Black Holes and the Antimatter Mystery

Tiny, exploding black holes might hold the key to a major cosmic puzzle: how the universe as we know it came to be. In the modern cosmos, matter is far more common than antimatter. This imbalance is strange because scientists have not found a definitive reason for why one dominates the other. Matter makes up everything we can see, smell, and touch. Antimatter, however, is rarely observed in nature. It is mostly identical to matter but has flipped electric charges. Antimatter can be released during radioactive decay or in high-energy particle collisions, but it does not form solid objects like stars or planets.

Some physicists propose that matter’s takeover of the universe involved tiny black holes. A black hole is a region where matter is packed so densely that nothing can escape its gravity, not even light. The specific black holes under consideration here would have been born in the first instants after the Big Bang, the event that marked the beginning of the universe. If these primordial black holes existed, they would have quickly evaporated and exploded. These massive explosions would have sent out powerful shock waves. These shock waves may have created the precise conditions necessary for matter to gain an advantage over antimatter.

Physicist Alexandra Klipfel shared this theory in March at the American Physical Society’s Global Physics Summit. She and her research team also described their findings in two papers posted to arXiv.org. It is important to note that studies on this preprint server have not yet been vetted by other scientists through peer review. However, the theoretical framework offers a compelling explanation for the matter-antimatter asymmetry.

Scientists generally believe the universe began with equal amounts of matter and antimatter. When matter and antimatter meet, they destroy one another, releasing energy. Without a mechanism to tip the balance in favor of matter, the universe would have been empty and devoid of structure. Tiny black holes could have shifted this balance, allowing for the formation of stars, planets, and galaxies. This scenario explains why the universe is not just a sea of energy but a place rich with solid matter.

Usually, black holes form when a massive star dies and collapses under its own weight. However, the black holes involved in this theory formed differently. They would have collapsed from fluctuations in the density of energy in the early universe. Each of these primordial black holes would have been surprisingly small, typically possessing only about as much mass as a small car. Despite their small size, their gravitational influence and subsequent energy release would have been significant.