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Physicists Closing in on Understanding the Primordial Universe

14 Aug , 2012

by

Photo of the ALICE detector at CERN. Photo courtesy of CERN.

Slamming barely nothing together is bringing scientists ever-closer to understanding the weird states of matter present just milliseconds after the creation of the Universe in the Big Bang. This is according to physicists from CERN and Brookhaven National Laboratory, presenting their latest findings at the Quark Matter 2012 conference in Washington, DC.

By smashing ions of lead together within CERN’s lesser-known ALICE heavy-ion experiment, physicists said Monday that they created the hottest man-made temperatures ever. In an instant, CERN scientists recreated a quark-gluon plasma — at temperatures 38 percent hotter than a previous record 4-trillion degree plasma. This plasma is a subatomic soup and the very unique state of matter thought to have existed in the earliest moments after the Big Bang. Earlier experiments have shown these particular varieties of plasmas behave like perfect, frictionless liquids. This finding means that physicists are studying the densest and hottest matter ever created in a laboratory; 100,000 times hotter than the interior of our Sun and denser than a neutron star.

CERN’s scientists are just coming off of their July announcement of the discovery of the elusive Higgs boson.

“The field of heavy-ion physics is crucial for probing the properties of matter in the primordial universe, one of the key questions of fundamental physics that the LHC and its experiments are designed to address. It illustrates how in addition to the investigation of the recently discovered Higgs-like boson, physicists at the LHC are studying many other important phenomena in both proton–proton and lead–lead collisions,” said CERN Director-General Rolf Heuer.

According to a press release, the findings help scientists understand the “evolution of high-density, strongly interacting matter in both space and time.”

Meanwhile, scientists at Brookhaven’s Relativistic Heavy Ion Collider (RHIC), say they have observed the first glimpse of a possible boundary separating ordinary matter, composed of protons and neutrons, from the hot primordial plasma of quarks and gluons in the early Universe. Just as water exists in different phases, solid, liquid or vapor, depending on temperature and pressure, RHIC physicists are unraveling the boundary where ordinary matter starts to form from the quark gluon plasma by smashing gold ions together. Scientists are still not sure where to draw the boundary lines, but RHIC is providing the first clues.

The nuclei of today’s ordinary atoms and the primordial quark-gluon plasma, or QGP, represent two different phases of matter and interact at the most basic of Nature’s forces. These interactions are described in a theory known as quantum chromodynamics, or QCD. Findings from RHIC’s STAR and PHENIX show that the perfect liquid properties of the quark gluon plasma dominate at energies above 39 billion electron volts (GeV). As the energy dissipates, interactions between quarks and the protons and neutrons of ordinary matter begin to appear. Measuring these energies give scientists signposts pointing to the approach of a boundary between ordinary matter and the QGP.

“The critical endpoint, if it exists, occurs at a unique value of temperature and density beyond which QGP and ordinary matter can co-exist,” said Steven Vigdor, Brookhaven’s Associate Laboratory Director for Nuclear and Particle Physics, who leads the RHIC research program. “It is analogous to a critical point beyond which liquid water and water vapor can co-exist in thermal equilibrium, he said.

While Brookhaven’s particle accelerator cannot match CERN’s record-setting temperature conditions, scientists at the U.S Energy Department lab say the machine maps the “sweet spot” in this phase transition.

Image caption: The nuclear phase diagram: RHIC sits in the energy “sweet spot” for exploring the transition between ordinary matter made of hadrons and the early universe matter known as quark-gluon plasma. Courtesy of the U.S. Department of Energy’s Brookhaven National Laboratory.

John Williams is a science writer and owner of TerraZoom, a Colorado-based web development shop specializing in web mapping and online image zooms. He also writes the award-winning blog, StarryCritters, an interactive site devoted to looking at images from NASA’s Great Observatories and other sources in a different way. A former contributing editor for Final Frontier, his work has appeared in the Planetary Society Blog, Air & Space Smithsonian, Astronomy, Earth, MX Developer’s Journal, The Kansas City Star and many other newspapers and magazines.

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beyondEinstein
Guest
beyondEinstein
August 14, 2012 7:55 PM

The changing function of everything in the universe is going on always.
The present scenery was not similar with past and also will not resemble
with the future, the present and past space-time energy absolute zero
of absolute time. As per formula of evolution; going to the last
border/boundary of everything of creation, it would be felt nothing
except touch of nature power. In the finalization of matter there is
nothing but energy or ray, so we can take the decision that “Everything of the present universe is the result of evolution of single energy of Power”. See at http://shahidurrahmansikder.wordpress.com/2010/01/03/21/

Lawrence B. Crowell
Member
Lawrence B. Crowell
August 15, 2012 1:40 AM
There are connections between QCD and gravity. A gluon can form an entanglement with another gluon that is a graviton. The structure of QCD plasmas or QGP has then connections to black holes and anti-de Sitter spacetimes. It is not difficult to quantize weak gravity. This is usually written as a bimetric theory g_{ab} = ?_{ab} + h_{ab}, where ?_{ab} is a flat spacetime (Minkowski) metric and h_{ab} is a perturbation on to of flat spacetime. Gravitons enter in if you write the perturbing metric term as h_{ab} = ?_a?_b, or ?_a^c = ?_a?^c. The Ricci curvature in this weak field approximation is R_{ab} – (1/2)Tg_{ab} = ?h^t_{ab}, with h^t_{ab} the traceless part of the metric, and ?… Read more »
Dav_Daddy
Member
August 15, 2012 8:21 AM

Hey LC, a little ot but does the graviton have any mass? I was curious because if the graviton is massless that would mean the gravitational would move at the speed of light, right?

Assuming that is correct couldn’t that be why we have been unable to detect gravitational directly as of yet?

Peter
Member
Peter
August 15, 2012 12:21 PM

Gravitational is a noun?

Dav_Daddy
Member
August 16, 2012 8:44 AM

That should have read “gravitational waves.”

Stupid auto correct on my new phone!

Torbjorn Larsson OM
Member
Torbjorn Larsson OM
August 15, 2012 1:30 PM
Naively it has to be massless, its field interactions should have infinite range. It also helps with consistency with relativity when having lightspeed travel of field changes. I guess in the low energy theory the non-linearities of general relativity is greatly suppressed, so the backreaction from changing gravity on the gravitons mediating the change is not much of a feedback loop. In other words, gravity has to be, and is, weak. This is presumably why we haven’t detected its waves outside of pulsar observations (unambiguously but “indirectly” as the saying goes) and even less its particles as of yet. When you go to high energies and it all blows up in your face, I hear. That is probably… Read more »
Lawrence B. Crowell
Member
Lawrence B. Crowell
August 15, 2012 10:52 PM

Gravity is very weak because particle masses are very small. The Planck unit of mass, the mass of a quantum of a black hole, is m_p = sqrt{?c/G} ~ 10^{-5}g. Elementary particles are 19 to 22 orders of magnitude smaller in mass.

If gravitons had mass Newton’s law of gravity would have a potential ? = GMme^{-ar}/r, which is the Yukawa potential.
LC

Lawrence B. Crowell
Member
Lawrence B. Crowell
August 15, 2012 1:50 PM
Gravitons are massless, as are the gauge particle of quantum chromodynamics (QCD) called gluons, but they do have energy which is equivalent to mass. They just do not have a rest mass so they can exist in a frame as a stationary particle. A free graviton is then without mass and its degrees of freedom are transverse, or field oscillations perpendicular to the direction of propagation. The role of mass is though a bit strange with gravitons that are in some collective interaction or coherence like laser photons. Since gravitons are related to gluons, or are entanglement states of gluons, we can think of QCD and gluons. A hadron is a bound state of quarks, where gluons are… Read more »
weeasle
Member
weeasle
August 17, 2012 9:53 AM
Nice post. I do my best to try and understand… I really liked your observatioin – ” If one had a perfectly mirrored box with lots of photons in there, one could measure an effective mass increase of the box due to the photons inside.” From my novice knowledge level, it reminds me of the photoelectric effect – I am fascinated no end to learn that photons can translate to electrons by interaction with certain metalic substrate/s.. Although both massless particles, the electron is closely associated with matter states and helps me understand your analogies – I am fascinated by all the developments from LHC and appreciate you taking the time to explain – When I get time… Read more »
Jeffrey Scott Boerst
Guest
August 15, 2012 5:25 PM

I’m a little confused… I’ve heard with the Higgs-like Boson announcement that now all the puzzle pieces per force carrier p[articles have been discovered, but I thought gravitons were still eluding ‘our’ searches… Or is it just Grav Waves that ‘we’ have still to detect? Or are they the same thing?

Lawrence B. Crowell
Member
Lawrence B. Crowell
August 16, 2012 12:49 AM
There is a prospect that we may find evidence for the quantum state of a gravity wave, or the graviton, before we detect a classical gravity wave from an astrophysical source. This would be a bit of an irony. There is indirect evidence for gravity waves with the Taylor-Hulst measurement of pulsar timing change. The Light Interferometry Gravity Detector (LIGO) is a huge Fabry-Perot plus Michelson-Morley interferometer that could detect gravitational radiation due to the collision of two black holes or black hole plus other object within about 50 million light years. There are plans to extend its sensitivity out to 300 million light years, if I remember the numbers right. It would be good to get this… Read more »
Lord Haw-Haw.
Guest
Lord Haw-Haw.
August 15, 2012 8:23 AM

The boundary line John Williams writes of is a little better explained by John Timmer on Ars Technica:

http://arstechnica.com/science/2012/07/heavy-ion-collisions-reveal-the-earliest-instants-of-our-universe

Effectively the physics behind heavy ion collisions differ from proton-proton collisions, with lead collisions at the LHC the concept is to spread a lot of energy over a large volume to reveal phenomena that a focused energy collision would miss, in the case of the latter (i.e. proton-proton collisions) as much energy as possible is focused on a tiny area.

Torbjorn Larsson OM
Member
Torbjorn Larsson OM
August 15, 2012 1:43 PM

On another note, has the primordial WordPress engine or its implementation on UT changed lately?

I get all these problems with the editor and flagging comments (say, as “like” comments) interacting with the browser security techniques and the browser interacting with the editor security techniques, which makes it tricky to respond on UT.

It works fine as long as you only make short comments without errors. As soon as you pass onto the trickier stuff, the stuff gets tricky – more than usual.

Jeffrey Scott Boerst
Guest
August 15, 2012 6:40 PM

I thought UT switched to Disqus forums a while ago.

Torbjorn Larsson OM
Member
Torbjorn Larsson OM
August 17, 2012 12:36 AM

You are right of course, but I thought they had merged.

bugzzz
Member
bugzzz
August 15, 2012 4:56 PM

Naive related question: regarding astronomy, has anyone yet figured out how we can peer into the primordial plasma soup? Or does this still remain a problem in that we can only see back to the point in time where the plasma has sufficiently cooled to be transparent?

Jeffrey Scott Boerst
Guest
August 15, 2012 6:38 PM

The latter… ‘we’ can’t see beyond the CMB at this point, as it marks the opaque boundary of the past Universe.

bugzzz
Member
bugzzz
August 15, 2012 7:12 PM

Too bad. Universe doesn’t want to give up its secrets so easily.

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