Science: Droplets of Primordial Soup, the nearly perfect liquid at the time of the big bang

A Scientific American article writes about recreating a Primordial Soup (PS) that existed for less than one microsecond beginning at about 10 microseconds after the big bang. Counterintuitively, it turns out that the PS is an almost perfect liquid where the ingredients flow freely. 

This has never been observed by humans in nature before. The PS, also known as quark-gluon plasma, is made of quarks and gluons, not Susan. Quarks and gluons are what protons and neutrons are made of, which, along with electrons, is what atoms are made of. Physicists make PS by smashing heavy atom nuclei (electrons stripped off) into each other in huge atom smashers. 

PS from atom smashers exists for a very short period of time, far less than one second. PS has not existed in the universe since about 10 microseconds after the big bang. This is probably about the closest to re-creating conditions in the universe that existed near to the instant the big bang commenced.  

The main goal of this research is to better understand the strong force, which is what holds protons and neutrons together in atomic nuclei and subatomic particles in protons and neutrons. The strong force is the strongest of the four known forces. It is 100 times stronger than the electromagnetic force (which binds electrons into atoms), 10,000 times stronger than the weak force (which governs radioactive decay), and a hundred million million million million million million (10^39) times stronger than gravity.

SciAm writes:

3 minute video about PS

A technician installing cables on the new sPHENIX detector at the Relativistic Heavy Ion Collider (RHIC) at Long Island's Brookhaven National Laboratory. Inside sPHENIX's cylindrical interior, atomic nuclei will collide to make droplets of a plasma that existed at the beginning of the cosmos.

Inside [the] proton you'll find a simple triad of three fundamental particles called quarks—two up quarks and one down quark. But the reality inside a proton is so much more complex that physicists are still trying to figure out its inner structure and how its constituents combine to produce its mass, spin and other properties.

The three quarks in the basic picture of the interior of a proton are merely the “valence quarks”—buoys bobbing on top of a roiling sea of quarks and antiquarks (their antimatter counterparts), as well as the sticky “gluon” particles that hold them together. The total number of quarks and gluons inside a proton is always changing. Quark-antiquark pairs are constantly popping in and out of existence, and gluons tend to split and multiply, especially when a proton gains speed. It's basically pure chaos. The strong force—the most powerful of the four fundamental forces of nature—keeps this mess confined to the insides of protons and neutrons. Except when it doesn't.

PS research is a window into the strong force, the least understood of all nature's forces. This force is described by a theory called quantum chromodynamics (QCD), which is so complicated that scientists can almost never use it to calculate anything directly.

Scientists predicted quark-gluon plasma long before they discovered it—although they expected it to take a very different form. .... Physicists expected that quarks and gluons, when freed from nuclei, would take the form of a uniformly expanding gaseous substance. “Usually fluids turn to gas as they get hotter,” says Berndt Mueller, a physicist at Duke University. It was a reasonable assumption: quarks and gluons aren't released from nuclei until they reach temperatures of trillions of degrees.

Instead of an expanding gas, the quark-gluon plasma looked like a liquid—a nearly perfect one, with almost no viscosity. In a gas, particles act individually; in a liquid, particles move cohesively. The stronger the interactions among particles—the more they can pull one another along—the “better” the liquid is at being a liquid. The RHIC observations showed that quark-gluon plasma exhibited less resistance to flow than any substance ever known. This, Mueller says, “was very much unexpected.”

In 2010 RHIC [Relativistic Heavy Ion Collider] researchers announced the first measurement of the quark-gluon plasma's temperature. It was a scorching four trillion degrees Celsius, far hotter than any other matter ever created by humans, and about 250,000 times hotter than the middle of the sun.

One of the biggest open questions about quark-gluon plasma is when, exactly, the quarks and gluons break out of their confinement. “Where is the boundary between usual matter and quark-gluon plasma?” physicist Haiyan Gao asks. “Where is the so-called critical point where the nuclear matter and the quark-gluon plasma coexist?”

Answering these questions could help with a larger goal: understanding the strong force, the most confusing of nature's fundamental forces. .... “You can write down the theory essentially in two lines, but actually solving it has not been really achieved,” theoretical physicist Bjoern Schenke says. “The process of confinement—how gluons and quarks are being trapped in the proton, for example—has not been solved.”

Inside RHIC's tunnels “stochastic cooling kickers” push the particles within the rings closer together to correct for their tendency to spread out as they travel. This ensures that as many particles as possible will collide inside the detectors.