In the universe’s earliest moments, it took the form of a scalding soup filled with particles called quarks and gluons. These particles zipped through liquidy plasma for just a few millionths of a second after the Big Bang. Now, physicists have recreated these conditions by producing tiny droplets of the same primordial soup that filled the universe right after it was born.
Making a modern version of the primordial soup — known as quark-gluon plasma — entails smashing atomic nuclei together at nearly the speed of light. This has often been done with very heavy atomic nuclei, but a new study published in Physical Review Letters has shown that similar results can be achieved with much smaller atomic nuclei. With this breakthrough, researchers are now on track to a vastly improved understanding of the earliest form of matter in the universe.
“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,” said study author You Zhou, a professor at Aarhus University, in a statement.
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The Hottest Primordial Soup
Right after the Big Bang, about 13.8 billion years ago, quarks and gluons filled the newborn universe. They frantically swam through plasma, all of them melding into a smooth, frictionless fluid. And at a few trillion degrees Fahrenheit, it also had the distinction of being the hottest liquid in existence.
It only took a few millionths of a second for this soup to cool. The quarks and gluons froze into protons and neutrons, the building blocks of atomic nuclei — and the rest is history.
Today, however, researchers are able to rewind back to the first moments of the universe by smashing atomic nuclei together, essentially generating 'little Big Bangs." This creates hot droplets that mimic primordial quark-gluon plasma, and just like the plasma from the universe’s first moments, these droplets only exist for a fraction of a second before expanding.
A Bowling-Pin Pattern
The researchers involved in the new study found that it’s possible to create plasma with much smaller atomic nuclei than previously thought, such as oxygen-16 and neon-20.
They’re not able to directly observe the plasma itself, but instead, they can see specific shapes from smashing the atomic nuclei together. These shapes turn out differently depending on the movement of particles; two oxygen nuclei make a rounded shape, while neon nuclei make a bowling-pin shape.
Studying the movement of these particles after they collide, according to the researchers, could help them unpack atomic nuclei in ways that haven’t been possible before.
“It is a bit like shining light on an object and seeing its shadow. You cannot see the object directly, but its shadow reveals its shape. In the same way, the movement of the particles reveals the geometric shape of the atomic nuclei that was present at the beginning of the collision,” said co-author Emil Gorm Dahlbæk Nielsen, a postdoctoral researcher at the University of Copenhagen's Niels Bohr Institute.
Smashing Atomic Nuclei Together
Physicists have long been interested in the shape and structure of atomic nuclei; research on these properties may be able to provide insight into the strong nuclear force, which is the most powerful force involved with holding matter together, according to the U.S. Department of Energy (the other three fundamental forces are gravity, electromagnetism, and the weak nuclear force).
In the past, studies have revolved around nuclear structure at low energies, such as observing the rotation and vibrations of atomic nuclei.
Smashing atomic nuclei into each other at high speeds, a more recent advance in the field, could shed light on previously unknown structures. Researchers still don’t know the boundary that defines the creation of quark-gluon plasma, but they plan on carrying out further experiments with even lighter nuclei, such as helium-4, in hopes of finding answers that could expand our knowledge of the early universe.
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Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
- This article references information from a study published in Physical Review Letters: Evidence of Nuclear Geometry-Driven Anisotropic Flow in O+O and Ne+Ne Collisions at √𝑠NN=5.36 TeV
- This article references information from the U.S. Department of Energy: DOE Explains...Quarks and Gluons