CERN Creates the Smallest Big Bang to Study the Beginning of the Universe

Scientists working at the European Organization for Nuclear Research (CERN) have created quark-gluon plasma by colliding oxygen-16 and neon-20 nuclei. The experiment recreated, in much smaller collisions, the dense and extremely hot conditions that existed approximately one millionth of a second after the Big Bang. This primordial form of matter, which no longer exists under natural conditions, opens a new opportunity to study the universe's earliest moments. Scientists call such events mini Big Bangs.

Quarks are fundamental particles that make up protons and neutrons, which in turn form atoms and all matter. Gluons are carrier particles that hold quarks together. During the universe's first microseconds, quarks and gluons were not yet confined inside protons and neutrons and existed as extremely hot plasma. As the universe expanded, matter cooled and quarks combined into larger particles.

For decades, physicists have studied this plasma primarily in large nuclear collisions involving heavy elements such as lead. The main question now is how small the collision can be and whether the particles produced will still behave like a droplet of liquid. Each of the two nuclei selected for the experiment weighs less than one-tenth as much as a lead atom. Lead, however, was previously considered one of the lightest elements capable of producing such plasma.

Despite the small nuclei, scientists recorded signals in the collisions that were consistent with quark-gluon plasma. For a very brief period, the resulting matter expanded collectively like a liquid before cooling and turning back into particles. Study co-author You Zhou said the result helps researchers better understand the fundamental conditions required to create primordial matter. The experiment could also clarify how this plasma behaved at the beginning of the universe and how it later transformed into the matter that exists today.