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Big-bang soup wins hotness record

What's hotter than Justin Bieber and Emma Stone put together? Guinness World Records says the hottest stuff made by humans is the multitrillion-degree quark-gluon plasma that was produced two years ago at the Brookhaven National Laboratory's Relativistic Heavy Ion Collider, or RHIC. The plasma, also known as big-bang soup, reached a temperature of 4 trillion degrees Celsius (7.2 trillion degrees Fahrenheit), which is 250,000 times hotter than the center of the sun.

Why so hot? RHIC's physicists were seeking to duplicate the conditions that existed just an instant after the big bang that kicked off the universe's expansion 13.7 billion years ago. At that temperature, the quarks and gluons that are almost always bound together in protons, neutrons and the like are jumping around in a free, soupy state. Studying that soup could reveal how the universe is put together at its most fundamental level.

The RHIC team created the soup by accelerating gold ions in a 2.4-mile-round magnetic ring in New York, and smashing them together at nearly the speed of light. They found that the proton-sized dollops of plasma had the characteristics of a nearly perfect liquid rather than a gas.

"There are many cool things about this ultra-hot matter,” Steven Vigdor, who leads Brookhaven’s nuclear and particle physics program, said in today's news release about the Guinness recognition. "We expected to reach these temperatures  that is, after all, why RHIC was built — but we did not at all anticipate the nearly perfect liquid behavior."

Vigdor noted that trapped atom samples also behave much like a liquid on the other end of the temperature spectrum, near absolute zero. "The unity of physics is a beautiful thing!" he said.

Like an aging celebrity, the 12-year-old RHIC is slowly being eclipsed by the new kid on the block — CERN's Large Hadron Collider on the French-Swiss border, which is in its fourth year of operation. One of the detectors at the LHC, known as ALICE ("A Large Ion Collider Experiment"), is doing similar big-bang experiments with lead ions, and has achieved temperatures higher than RHIC's. Some researchers have estimated that ALICE's soup gets as hot as 10 trillion degrees

"The energy density at the LHC is a factor of three higher than at RHIC," Brookhaven quotes CERN physicist Despina Hatzifotiadou as saying. "This translates to a 30 percent increase in absolute temperature compared to the value achieved by RHIC. So I would say that ALICE has the record!"

The only holdup is that ALICE's team has not yet published an official temperature measurement for its quark-gluon plasma, and as Brookhaven notes, "the Guinness team is nothing if not official." That means there's still plenty of time to raise a pint of Guinness (or your favorite alternate beverage) and drink a toast to RHIC's hotness.

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Alan Boyle is's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.