This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: What happened in the first moments of the universe—before the building blocks of life and the world we know today came into existence? Physicists at the CERN research facility in Switzerland are trying to answer this question by recreating some of the extreme conditions that prevailed in the universe during its earliest history.
Now, researchers from the Niels Bohr Institute, together with colleagues from the international ALICE collaboration, have come one step closer to understanding those conditions. At CERN, researchers can make atomic nuclei collide at almost the speed of light, creating tiny droplets of the primordial matter that filled the universe during its first millionth of a second. This matter is known as quark-gluon plasma and is thought to have been the earliest form of matter in the universe.
For many years, scientists have assumed that creating this plasma required collisions between very heavy atomic nuclei such as lead. But physicists from the Niels Bohr Institute have now succeeded in creating the primordial matter by smashing the much smaller nuclei of oxygen-16 and neon-20 together. "We have pushed the boundary for how small the atomic nuclei can be while still recreating this primordial matter—what you could call a little Big Bang.
We now know more about the fundamental conditions required for matter to transition into this extreme state," says associate professor You Zhou, who led the experiment and until recently worked at the Niels Bohr Institute at the University of Copenhagen. "Hopefully, this will help us better understand how the plasma behaved during the first moments of the universe—and how it later evolved into the forms of matter that everything around us is made of." The research findings, produced as part of the international ALICE experiment, have been published in the journal Physical Review Letters. When the atomic nuclei collide, their constituents are transformed into a tiny droplet of quark-gluon plasma that exists for a tiny fraction of a second.
The droplet of extremely hot matter then expands. Researchers cannot observe the plasma directly, but they can measure the particles that the matter turns into shortly afterward. Here, it turns out that the movement pattern of the particles reveals the shape of the atomic nucleus.
While collisions between two oxygen nuclei produce a more rounded pattern, collisions involving neon produce a bowling-pin-shaped pattern. "The particles from the primordial matter are directly governed by the geometric shape of the atomic nucleus. If the two nuclei we smash together are spherical, we get one pattern.
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