Scientists create new state of matter
Scientists have created what they describe as a “Little Bang” inside which are the conditions that existed a thousandth of a second after the birth of the Universe in the so-called Big Bang.
In doing so, they have made a form of matter that has not existed for 15 billion years.
It is called a “quark-gluon” soup or plasma. By studying its properties, and the laws it obeys, scientists will gain a fresh insight into the evolution of the Universe during one of its formative phases.
In short, the reason why there are stars, galaxies and indeed planets and people is because of the properties of the quark-gluon plasma.
The breakthrough is the result of several experiments by researchers from 20 countries working on the Heavy Ion programme at the Cern nuclear research centre in Geneva, Switzerland.
The scientists say they have produced compelling evidence for the new state of matter in which quarks, instead of being bound up by gluons into more complex particles such as protons and neutrons, are liberated to roam freely.
It is believed that quarks are one of the fundamental building blocks of matter. In the Universe we know today, the particles come in pairs or threes. But when the Universe was more energetic, in its earliest moments, things were probably different.
Theory predicts that the new state of matter that the scientists have created, in which quarks were single and free to move about, must have existed before the formation of matter as we see it now. But until Cern’s success, such a state of matter has not been confirmed experimentally.
Professor Luciano Maiani, Cern’s Director General, said: “The combined data coming from the seven experiments on Cern’s Heavy Ion programme have given a clear picture of a new state of matter.
“This result verifies an important prediction of the present theory of fundamental forces between quarks.” He added: “It is also an important step forward in the understanding of the early evolution of the Universe. We now have evidence of a new state of matter where quarks and gluons are not confined. There is still an entirely new territory to be explored.”
The crucial data was obtained by colliding ionised lead atoms to create microscopic explosions that although very small have very high concentrations of energy. Such “Little Bangs” have staggering properties, being at a temperature of two million million degrees and 20 times denser than the nucleus of an atom.
These high energies, it was hoped, would break down the forces which confined quarks inside more complex particles.
The tracks produced by particles after a collision This is what the scientists appear to have witnessed. The high-energy lead ions were crashed into targets inside seven different detectors. The collisions created conditions that have never before been reached in laboratory experiments.
The data from the collisions provides compelling evidence that a new state of matter has been created. It has many of the characteristics of the theoretically-predicted quark-gluon plasma.
The researchers point out that the data from any one of the seven lead ion experiments were not enough to give them the full picture, but the combined results from all experiments do provide the evidence required. Creating the new state of matter is only a beginning for the Cern researchers. The next step is to study how it behaves at different temperatures and densities. This will allow the scientists to probe key moments in the evolution of the Universe of stars and galaxies from the Universe of quarks and gluons.