Is dark matter made of 'Fermi balls' forged in the Big Bang?

Artist's impression of dark matter at the beginning of the universe.
The mysterious dark matter, which exerts gravity but does not interact with light, might be composed of tiny black holes that permeate the universe. According to new theories, the black holes could have been formed from Fermi balls or quantum "bags", which are subatomic particles called fermions and smooshed in dense pockets in the early days of the universe.

This theory could help explain how dark matter became the dominant force in the universe.

"We found that in some cases the Fermi balls can be so dense that the fermions get too close to one another, triggering the collapse a Fermiball [in]to a dark hole," Ke-Pan Xie from the Center for Theoretical Physics, Seoul National University, South Korea told Live Science.

Related: 10 amazing discoveries about black holes

Xie and Kiyoharu, a collaborator at the Center for Theoretical Physics have created a new scenario to explain dark matter's rise to dominance of the universe. This is because, during an amazing transformation of the cosmos, a new type of particle got trapped. They collapsing to a point so small that they became black holes. These black holes then filled the universe with the necessary weight to explain dark matter.

The case for primordial black hole

Dark matter is a mysterious substance that dwarfs astronomers and physicists. It makes up over 80% of all large structures, galaxies included, as well as the cosmic web.

It is possible that dark matter was created from black holes. Black holes emit no light, which is why they are similar to dark matter. "As a type of nonluminous, compact object black holes are a natural explanation to the dark matter," Xie stated.

Astronomers have known for years that dark matter cannot be explained by normal, stellar-mass black hole. Because not enough stars have been formed over the course of the universe's history to produce enough black holes to explain the dark matter.

Some mind-boggling physics was evident in the early moments of the universe. Maybe there was some kind of physics going on back then that created trillions upon trillions of smaller black hole. These black holes could continue to exist into the future, possibly solving the dark matter puzzle.

To explain dark matter, however, one would need to have enough black holes.

Artist's impression of the black hole. According to some theories, primordial black holes could be made up of dark matter. (Image credit: Shutterstock)

A fluffy universe

Xie, Kawana and others added many ingredients to their model. This is described in a June paper to the arXiv preprint database. The paper has not been peer-reviewed. The universe was very young and very dense. These extreme conditions permit some physical processes to occur that are not possible in the current-day universe.

A scalar field is the first ingredient. This is a quantum mechanical entity that covers all of space. One example is the well-known Higgs Field, which gives matter its mass. The universe expanded and cooled, the scalar field went through a phase transition. It transformed from one quantum mechanical state into another.

The phase transition did not occur in the whole universe at once. Xie stated that the phase transition occurred at a handful of points and then spread to other areas, just like a few bubbles in a pot boiling water combining to create larger bubbles.

"This is called a first order phase transition: Water moves from the 'liquid phase to the 'gas phase', and the former first exists as growing bubbles," Xie stated.

These points are spread out like a bunch fizzing bubbles by the new scalar state state, also known as the "ground state". The bubbles eventually merge and the scalar fields completes its transition.

How to make a Fermi Ball

Xie, Kawana and another ingredient were needed to create primordial black holes that can seed dark matter. They added a new type of fermion into their model. Fermions are the category of particles that makes up the building blocks for the universe. Fermions are the particles that make up the building blocks of the universe.

These fermions were free to move within the scalar fields in the early universe. According to the recipe Xie & Kawana created, the fermions could not penetrate the tiny foaming bubbles in the new ground state.

The bubbles grew and the fermions began to crowd into the pockets. These became Fermi balls. That's when everything went haywire.

This is because the scalar field Xie & Kawana proposed in their paper created an additional force between fermions called a Yukawa interaction. Fermions are not fond of being crammed together in small volumes. However, the scalar fields added an attractive force that could overcome that natural repulsion.

Protons and neutrons, for example, are made up of smaller particles called quarks. Quarks, which are fermions, normally dislike each other but a stronger force, called the strong force, binds them together. This force can be modeled in Yukawa interactions, similar to early-universe physics as seen in Xie's and Kawana’s models.

According to Xie, Kawana, the Yukawa attraction was established and it was over for the Fermi balls. The clumps formed black holes by being pushed into tiny pockets in a rapidly changing universe.

These black holes survived the end of phase transition and continued to flood the universe with dark matter.

That's at least the idea. This is a radical suggestion. However, it's necessary to have radical suggestions and observations in order to move forward with the physics of early universe and dark matter.

Original publication on Live Science