“a hot, dense soup of quarks and gluons.”

As the BBC noted, the Large Hadron Collider at Cern has switched from firing beams of protons to beams of heavy [lead] ions.  From the BBC report

One of the scientists who will be taking a part in the experiment is David Evans from the University of Birmingham, UK.

“Although the tiny fireballs will only exist for a fleeting moment (less than a trillionth of a trillionth of a second) the temperatures will reach over ten trillion degrees, a million times hotter than the centre of the Sun,” said Dr Evans.

“At the temperatures generated, even protons and neutrons, which make up the nuclei of the atoms, will melt, resulting in a hot, dense soup of quarks and gluons.”

The researcher said that the temperatures and densities that the collider will aim to create will be the highest ever produced in an experiment.

And the collisions have already begun.

The Guardian’s pet particle physicist, Jon Butterworth, explains what’s going on.

As particles collide at higher and higher energies, different physical effects occur. For example, if atoms collide with high enough energies, they knock electrons off each other – they ionise. Experiments which map the cosmic microwave background (like COBE, WMAP and Planck) look at the physics from the moment (about 400,000 years after the start) when the universe got so cool that this ionisation stopped happening. Before that everything was plasma. Plasma is the stuff which glows in fluorescent lightbulbs.

Go further back, a few minutes after the big bang, and energies get so high that even atomic nuclei can’t hold together. At this point, protons and neutrons are everywhere. These are the kind of energies you need for nuclear fusion, as is being attempted at ITER.

Back a big step further (about 0.00000000001 seconds after the big bang) and the protons and neutrons can’t even stay whole. The quarks and gluons that they are made of spread over the whole universe (which is quite small at this point). This is a new form of matter we refer to as “quark-gluon plasma”, though evidence from experiments at RHIC indicates it may behave more like a quark-gluon liquid in fact. This is the stuff the LHC will be able to reproduce now, and which the experiments will study – especially ALICE, which is built for this purpose.

The concentrations of energy we get in proton collisions are even higher. They take us back to energies above another threshold – the electroweak symmetry breaking scale – above which the weak nuclear force is as strong as the electromagnetic force, and maybe Higgs bosons roam free. This would be about 10-34 seconds after the start. That is thirty-four zeros between the decimal point and the 1.

Before this energies are even higher and frankly no one knows, though there are plenty of theories.

He also points to a more detailed, technical, explanation here.

And a quick reminder of what it’s all about, wrinkles aside…

And here’s an interesting, but un-embeddable, short video of Murray Gell-Mann discussing his work on quarks, symmetry and ignoring received wisdom.  As Jon Butterworth noted

I am very convinced by his lucid description of how unnecessary concepts get in the way, and how ditching “what everybody knows” can lead to sudden progress.

Of course, for all of you out there with budding new theories, this is only true if the data back you up.

The data backed up Gell-Mann spectacularly: his quarks (and the gluons they exchange) lie behind all the jets we are seeing now at the LHC.

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