For instance, the electrons, protons and neutrons that make up the atoms in your body are all fermions. Fermions are a category of particles that make up the building blocks of the universe. So they added a new kind of fermion to their model. To make primordial black holes that seed dark matter, however, Xie and Kawana needed another ingredient. Eventually, the bubbles merge completely, and the scalar field finishes its transition. The new scalar field state, called the "ground state," spreads out from these points like a bunch of fizzing bubbles.
"This process is called a first-order phase transition: Water transfers from 'liquid phase' into 'gas phase,' and the latter first exists as growing bubbles," Xie said. Instead, there were a few points where the transition began from and then spread - just as a few bubbles in a pot of boiling water merge to form bigger bubbles, Xie said. That phase transition didn't happen all at once throughout the entire universe. (The well-known Higgs field, which gives matter its mass, is an example of one.) As the universe expanded and cooled, that scalar field underwent a phase transition, transforming from one quantum mechanical state to another. The first ingredient is something called a scalar field, which is a quantum mechanical entity that encompasses all of space. These extreme conditions allow some physical processes that do not happen in the normal conditions of the present-day universe. (The paper has not yet been peer-reviewed.) They started with a very young, very hot, very dense universe. Xie and Kawana added several ingredients to their model, which is described in a paper published in June to the preprint database arXiv. (Image credit: Shutterstock) A frothy universe Primordial black holes could make up dark matter, according to some theories. Those black holes could persist to the present day, potentially solving the dark matter riddle.īut to explain dark matter, the theory would have to make enough black holes.Īn artist's impression of a black hole. Perhaps whatever was going on back then spawned trillions of smaller black holes. That's because not nearly enough stars have formed in the history of the universe to create enough black holes to account for the known dark matter.īut the earliest moments of the universe featured some pretty mind-boggling physics. "As a kind of nonluminous and compact object, black holes are a natural explanation for the dark matter," Xie said.īut astronomers have known for a long time that normal, stellar-mass black holes can't explain the universe's dark matter. After all, black holes, like dark matter, emit no light. One intriguing possibility is that dark matter originated from black holes. Astronomers and physicists cannot explain dark matter, the mysterious substance that makes up more than 80% of the mass of every large structure, from galaxies to the cosmic web itself, in the universe.
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