The Big Bang produced matter and its counterpart called antimatter in equal amounts when the universe began but antimatter has now become extremely rare. Some phenomena may have resulted in the dominance of matter but scientists have difficulty finding evidence to back up theories.

In a new experiment, however, scientists have measured the forces responsible for making certain particles of antimatter stick together. The findings, which were published in the journal Nature on Nov. 4, may allow scientists to investigate why antimatter has become scarce in the cosmos today.

"Antimatter is extremely rare. It's a huge mystery!" said physicist Aihong Tang, from the Brookhaven National Laboratory, who was involved in the study.

"Although this puzzle has been known for decades and little clues have emerged, it remains one of the big challenges of science. Anything we learn about the nature of antimatter can potentially contribute to solving this puzzle."

Tang and colleagues conducted an experiment using the Relativistic Heavy Ion Collider (RHIC) at Brookhaven. The giant particle accelerator smashed atoms of pure gold, producing antimatter particles with the raw energy of the collisions.

The researchers then looked at the antimatter counterpart of proton. Proton is the positively charged particle at the center of a matter's atom. Its antimatter counterpart, called antiproton, is negatively charged.

The physicists measured the force of interaction between two antiprotons and discovered that the force between these pairs is attractive just as the strong nuclear force that binds protons together inside of the atom.

Since antimatter behaves differently than matter, the result of the experiment suggests that some asymmetry may be at work, which could explain the dominance of matter in the universe and the scarcity of antimatter.

The study is an addition to the collection of research that found no difference in the behavior of matter and antimatter. Discrepancies would help scientists determine why matter is more dominant than antimatter.

The research also offered insights into the structure of the nuclei of antimatter composed of bound antiprotons and antineutrons.

"Our results provide direct information on the interaction between two antiprotons, one of the simplest systems of antinucleons, and so are fundamental to understanding the structure of more-complex antinuclei and their properties," the researchers wrote.

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