Short answer: quark-gluon plasma (QGP) is a state of matter so hot that protons and neutrons melt into a thick “soup” of quarks and gluons. It filled the whole universe in the first few millionths of a second after the Big Bang. Today, scientists make tiny drops of it for a split second in giant particle colliders.
What is it, in simple words?
Normally, quarks are locked inside protons and neutrons. The strong force will not let them out. But if you heat matter to a very high temperature, or squeeze it very hard, the quarks break free of their groups. They move around together with the gluons that glue them. That mix is quark-gluon plasma.
- Quarks: the building blocks of protons and neutrons. See the six quark flavours.
- Gluons: the particles that carry the strong force.
- Plasma: a hot, crowded state where the pieces move around freely.
How hot is it?
Very hot. In 2010, scientists at the Relativistic Heavy Ion Collider (RHIC) in New York measured about 4 trillion degrees Celsius in their plasma. That is roughly 250,000 times hotter than the core of the Sun, and about twice the temperature needed to melt protons and neutrons. It was the hottest temperature ever reached in a lab at that time.
A “perfect” liquid, not a gas
Scientists first expected QGP to act like a hot gas. In 2005, RHIC results showed something surprising: it flows like a liquid with almost no friction, which they called a “nearly perfect liquid”. Later experiments at the Large Hadron Collider (LHC) in Switzerland found the same kind of behaviour.
How do scientists make it?
- They speed up heavy atoms, such as gold or lead, to nearly the speed of light.
- They smash them head-on in a collider.
- The energy of the crash is squeezed into a space about the size of a nucleus, making a tiny fireball of plasma.
- The fireball lasts for an extremely short time, far less than a billionth of a second. Then it cools and turns into ordinary particles that fly into the detectors.
Because the plasma disappears so fast, nobody sees it directly. Scientists study the particles that come out and work backwards to learn what happened inside.
New in 2025 and 2026: even small collisions may make it
For years, scientists thought you needed very heavy nuclei, like lead (about 200 protons and neutrons), to make QGP. In July 2025, the LHC collided much lighter nuclei for the first time: oxygen (16 protons and neutrons) and neon (20).
- In 2026, the ALICE experiment reported evidence that fast quarks and gluons lose energy as they cross the matter made in oxygen-oxygen collisions, a classic sign of QGP. They said the result is about 4.9 sigma, or roughly a 1 in 2 million chance that it is an accident.
- Another LHC experiment, CMS, had also seen hints of the same energy loss in oxygen collisions.
- The LHCb experiment found that charm quarks are held back more in neon collisions than in oxygen collisions, which fits the idea that a bigger collision makes a bigger drop of plasma.
The big takeaway: drops of QGP may form in much smaller collisions than scientists once believed. The final answer is still being worked out.
Why does it matter?
- The early universe. It shows us what the universe was like in its first microseconds.
- The strong force. It lets scientists test how quarks and gluons behave when they are free.
- Neutron stars. The inside of the heaviest neutron stars may hold cold, very dense quark matter, which is different from the hot QGP made in colliders. See what a quark star is.
Quick FAQ
Is quark-gluon plasma dangerous?
No. The amount made is tiny, and it lasts for a split second inside a machine.
Where is it made?
Mainly at RHIC in the United States and at the LHC at CERN in Switzerland.
Is it the same as the plasma in a lightning bolt?
No. Ordinary plasma is made of atoms that have lost electrons. Quark-gluon plasma is a much more extreme state, where even protons and neutrons have melted.
More: quark vs atom and what is smaller than a quark. Back to the science section