How the universe evolved from a liquid
Published 22/11/2010 | 12:25
The universe was a super-hot liquid in the moments immediately after its birth, according to the first results from an experiment to recreate the conditions of Big Bang.
Scientists working at the world's largest particle smasher – the Large Hadron Collider at CERN near Geneva, in Switzerland – have found that an exotic soup more than 10 trillion degrees Celsius in temperature was created immediately after the birth of the universe.
This sticky, gloopy substance, known as a quark-gluon plasma, behaved like a hot liquid, according to their results.
This provided the perfect environment for the first particles and atoms to form, which later led to the stars and galaxies that surround us today.
The findings have surprised physicists as they contradict the accepted view of what happened in the immediate aftermath of the creation of the universe – that the Big Bang threw out a superheated gas that clumped together to form matter.
"In the very first instances of the universe, it was actually behaving like a very dense liquid," explained Dr David Evans, a particle physicist at the University of Birmingham who is the UK's lead investigator in the experiment.
"These results are telling us about the evolution of the early universe, which inevitably will have had implications for how the universe looks today.
"We have got to do a lot more analysis and put a lot more thought in to understanding this, but it is a really fascinating result."
The results are the first to be released by a multinational group of more than 1,000 researchers who have been working on an experiment with the Large Hadron Collider that began two weeks ago.
They have been using the particle accelerator to smash atoms of lead together inside a detector known as ALICE in a bid to create "mini big bangs" that are thought to mimic the conditions seen in the fractions of seconds after the universe was created.
The tiny fireballs created inside the 17 mile long particle accelerator, which is buried 300ft beneath the Alpine foothills along the Swiss-French border, reached more than 10 trillion degrees centigrade for a fraction of a second.
At these temperatures the atoms and the particles that make them up cease to exist, melting instead into their constituent parts, known as quarks and gluons.
Physicists widely believed that at the high temperatures created in the aftermath of the Big Bang, the forces that normally bind quarks and gluons together would have weakened considerably, resulting in a substance that behaved similar to a gas.
Previous research five years ago at the Relativistic Heavy Ion Collider in Upton, New York, managed to create temperatures of four trillion degrees and showed at these temperatures the quark-gluon plasma was similar to a liquid, but many expected as the temperature increased it would become more gas like.
The latest findings from CERN, however, suggest this is not the case and the results are expected to turn conventional thinking in physics on its head as scientists attempt to figure out why the quark-gluon plasma does not behave as predicted.
Dr Evans said: "The theories suggested that the forces that hold quarks together start to weaken at the kind of temperatures we would see immediately after the Big Bang and the quarks would move around freely like a gas.
"We found the strong force that binds them together still maintains a lot of its power, even at these high temperatures. The quarks are still interacting with each other far more than we would have expected.
"These results should help us understand more about that mysterious period before protons and neutrons formed in the early universe."
Professor Brian Cox, a particle physicist at the University of Manchester and presenter of the forthcoming BBC series Wonders of the Universe, said the findings had opened up a lot of questions about what the early universe looked like.
He said: "They are using a metaphor of sorts to explain how it looked as it will have been unlike any liquid we are used to."
"They are talking about the strength of the interaction between the quarks and how these particles behave together. They must interact far more strongly than was expected and so behave like a liquid.
"These experiments are providing us with a new energy regime so to see unexpected behaviour is very exciting. These findings are very interesting."