Update: CERN’s Search for the Hidden Mass of the Universe


The Higgs boson is meant to give mass to everything, including itself. It's also its own antiparticle. That isn't a boson, that's a Zen riddle written into reality by some kind of Cosmic Buddha – which hasn't stopped scientists seeking it with gigantic particle blasters, and there are very few places left for it to hide.

The idea is that we all exist in a vast Higgs field, and more "massive" objects are simply affected more strongly by it, Higgs interactions making them harder to move (or to stop once they start). Put another way: the more donuts you eat, the more the Higgs field notices you.

You might ask: If the Higgs is hammering at everything ever, why do we need five billion dollars of particle accelerator to see even one? That's a very good question, and not one with the simplest answer. The Higgs "mediates" mass interactions, the same way photons mediate electromagnetic forces. So electromagnetic interactions can only operate at the speed of light, but you don't see flashes of photons every time you wave a magnet around – the mediating photons are "virtual". In the same way, the Higgs defines mass interactions without seeming to turn up in actual person.

But we CAN make photons come out to play, we just need enough energy and the right setup. Likewise, we're working to get the shy Higgs particle out into the open – particle accelerators are engaged to ram subatomic particles together at titanic energies. If the right ingredients come together with enough energy we'll finally see one, but "enough" energy is quite a lot. Remember that Higgs particles do have mass (if only because they play with themselves) and the energy required is then set by E = mc2.

The range of E is what's being searched right now: experiments at Fermilab, CERN and other institutes are ruling out whole swathes of the spectrum, leaving the Higgs hiding between 114 and 160 GeV/c2 (or maybe a little window from 180-185, if it's anywhere at all). The search continues with the LHC's eighty kilometer barrel aimed at those few remaining blanks. Stephen Hawking has bet that the elusive Higgs will never be observed.

In the image at the top of the page, an experiment to collide lead nuclei together at CERN's Large Hadron Collider physicists from the ALICE detector team discovered that the very early Universe was not only very hot and dense but behaved like a hot liquid.

By accelerating and smashing together lead nuclei at the highest possible energies, the ALICE experiment has generated incredibly hot and dense sub-atomic fireballs, recreating the conditions that existed in the first few microseconds after the Big Bang. Scientists claim that these mini big bangs create 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. These 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.

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.

Dr David Evans, from the University of Birmingham’s School of Physics and Astronomy, and UK lead investigator at ALICE experiment, 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.”

The team has also discovered that more sub-atomic particles are produced in these head-on collisions than some theoretical models previously suggested. The fireballs resulting from the collision only lasts a short time, but when the ‘soup’ cools down, the researchers are able to see thousands of particles radiating out from the fireball. It is in this debris that they are able to draw conclusions about the soup’s behavior.

Physicists working on the ALICE experiment will 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 Daily Galaxy via CERN


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