Early Universe was a liquid - First results from the Large Hadron Collider's ALICE experiment

Scientists are amongst a team of researchers who have found that the very early Universe was not only very hot and dense but behaved like a hot liquid. The discovery is the result of accelerating and smashing together lead nuclei at the highest possible energies in the Large Hadron Collider’s (LHC’s) ALICE experiment, recreating the conditions that existed in the first microseconds after the Big Bang.

Scientists from the University of Birmingham, funded by the STFC, are playing a key role in this new phase of the LHC’s programme which comes after seven months of successfully colliding protons at high energies.

The lead-ion collisions generate incredibly hot and dense sub-atomic fireballs or ‘mini Big Bangs’ with temperatures of over ten trillion degrees.  At these temperatures normal matter is expected to melt into an exotic, primordial ‘soup’ known as quark-gluon plasma.  The first results from lead collisions have already ruled out a number of theoretical physics models, including ones predicting that the quark-gluon plasma created at these energies would behave like a gas.

Dr David Evans, from the University of Birmingham’s School of Physics and Astronomy, is the UK lead investigator at the ALICE experiment. Dr Evans said, “Although it is very early days we are already learning more about the early Universe. These first results would seem to suggest that the universe would have behaved like a super-hot liquid immediately after the Big Bang.”

Although previous research in the USA* at lower energies indicated that the hot fire balls produced in nuclei collisions behaved like a liquid, many expected the quark-gluon plasma to behave like a gas at these much higher energies.

For more information about the discovery see the University of Birmingham’s press release (link opens in a new window).

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Notes to editors

Two papers detailing this research have been submitted for publication:

• Elliptic flow of charged particles in Pb-Pb collisions at 2.76 TeV (link opens in a new window) |
• Charged-particle multiplicity density at mid-rapidity in central Pb-Pb collisions at sqrt(sNN) = 2.76 TeV (link opens in a new window)

* More information on the previous, lower energy results from the USA can be found on the Brookhaven National Laboratory website (link opens in a new window)

Images and captions

Pictures of lead collisions and the ALICE detector can be found on the Birmingham University website (link opens in a new window) and the CERN website (link opens in a new window). Images should be credited to CERN unless otherwise stated.

Contact

• Bekky Stredwick
  Press Office
  STFC Rutherford Appleton Laboratory
  Tel: +44 (0)1235 445 777
  Mob: +44 (0)7825 861 436
  
  
• Dr David Evans
  University of Birmingham
  Mob: +44 (0)798 040 6171

The ALICE Experiment

The 10,000 ton ALICE experiment has been specifically designed to study the extreme conditions produced in these lead collisions.  ALICE is one of the four main experiments at the LHC designed to study the physics from ultra-high energy proton-proton and lead-lead interactions.

Physicists working on the ALICE experiment study the properties, still largely unknown, of the state of matter called a quark-gluon plasma. This will help them understand more about the strong force and how it governs matter; the nature of the confinement of quarks – why quarks are confined in matter, such as protons; and how the Strong Force generates 98% of the mass of protons and neutrons.

The ALICE Collaboration consists of around 1000 physicists and engineers from about 100 institutes in 30 countries. The UK group consists of eight physicists and engineers and seven PhD students from the University of Birmingham. It plays a vital role in the design and construction of the central trigger electronics (the ALICE Brain) and corresponding software. In addition, the UK group is making an important contribution to the analysis of ALICE data.

CERN

CERN is one of the world’s largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works.

University of Birmingham

The University of Birmingham is a truly vibrant, global community and an internationally-renowned institution. Its work brings people from across the world to Birmingham, including researchers and teachers and more than four thousand international students from nearly 150 different countries.

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