Scientists Create the Littlest Big Bang to Study the Universe's Origins

In the very first moments of the universe, matter didn’t exist as we know today. A millionth of a second or so after the big bang , the universe was a dense, hot soup scientists call quark-gluon plasma (QGP). For several years, particle colliders —which smash molecules together at nearly the speed of light—have been able to replicate this state, but often using heavy elements like lead.

Now, a recent experiment by the European Organization for Nuclear Research (also known as CERN from its French acronym) has demonstrated this plasma can be produced by much smaller collisions. Since there’s no longer an accessible natural source of this primordial sludge, these micro big bangs can help reveal what happened in the first few minutes of our universe.

First, a little context. Quarks are what make up protons and neutrons, which, in turn, are the building blocks of atoms and thus all matter. Meanwhile, gluons—as their name suggests—stick quarks together.

During the first microseconds of the universe, quarks and gluons were not yet confined within protons and neutrons but instead formed an extremely hot plasma. As the universe expanded, the matter cooled, and the quarks condensed into larger particles.

After decades of studying QGP in large nuclear collisions, physicists are now trying to understand the limits of this strange state of matter . In particular, they are exploring just how much they can scale down a collision and still observe a collection of particles that behaves like a drop of fluid.

According to a recent article in Physical Review Letters , CERN and an international team of collaborators were able to generate the substance using oxygen-16 and neon-20. Both are less than a tenth of the weight of a lead atom, which was previously considered one of the lightest elements capable of generating QGP.

“We have pushed the boundary for how small the atomic nuclei can be while still re-creating 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,” You Zhou, a researcher at the Niels Bohr Institute in the Netherlands and a coauthor of the study, explained in a press release .

The scientists found that, despite the small size of the oxygen and neon nuclei, the collisions produced signals consistent with the behavior they expected to find in QGP. For an instant, the generated matter appeared to expand collectively like a fluid before cooling and reverting to particles.

“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,” Zhou added.