Exactly At the beginning of the universe, the matter we know today did not yet exist. Roughly one-millionth of a second after the Big Bang, the cosmos was filled with an incredibly hot, dense state of matter known as quark-gluon plasma (QGP). Today, particle colliders can recreate this primordial plasma by smashing atomic nuclei together at nearly the speed of light—typically using heavy elements such as lead.
Now, experiments conducted by the European Organization for Nuclear Research (CERN) show that quark-gluon plasma can also form in much smaller nuclear collisions. These “mini Big Bangs” offer scientists a way to investigate how the universe’s earliest state of matter formed and evolved, since no natural source of primordial QGP remains.
Quarks are the fundamental particles that make up protons and neutrons—the building blocks of atomic nuclei. Gluons, meanwhile, are the particles that carry the strong nuclear force, binding quarks together.
During the universe’s first microseconds, quarks and gluons were not confined within protons and neutrons. Instead, they existed as an extremely hot quark-gluon plasma. As the universe expanded and cooled, the quarks and gluons combined to form larger particles, eventually producing the matter that makes up the visible universe.
After decades of studying QGP in high-energy collisions involving heavy atomic nuclei, physicists are now examining the smallest systems capable of producing this unusual state of matter. Their goal is to determine how far nuclear collisions can be scaled down while still generating groups of particles that behave collectively like a tiny fluid.
According to a recent article in Physical Review Letters, CERN researchers and an international team created signals consistent with quark-gluon plasma using oxygen-16 and neon-20 nuclei. Both nuclei are less than one-tenth the mass of a lead nucleus, previously considered one of the lightest systems capable of producing QGP.
“We have pushed the limits of how small atomic nuclei can be while still recreating this primordial form of matter—the so-called ‘little Big Bang.’ We now know more about the fundamental conditions required for matter to reach this extreme state,” explained You Chou, a researcher at the Niels Bohr Institute in the Netherlands and co-author of the study. Read the press release.
Despite the small size of the oxygen and neon nuclei, the collisions produced patterns consistent with QGP behavior. For a brief moment, the newly created matter expanded collectively like a fluid before cooling and transforming back into individual particles.
“We hope these results will help us better understand how quark-gluon plasma behaved during the universe’s earliest moments and how it eventually evolved into the forms of matter that make up everything around us,” Chou added.
This story was originally published in the Spanish edition of WIRED and translated from Spanish.
Source: www.wired.com