Physicists create hottest-ever substance

Posted by Emma Woollacott

Scientists say they've created the highest temperature since the Big Bang - 250,000 times hotter than the sun.

Using the Brookhaven National Laboratory’s Relativistic Heavy Ion Collider (RHIC), they've hit a temperature of four trillion degrees Celsius, and had their achievement officially recognized by Guinness World Records.

When the RHIC collides gold ions at nearly the speed of light, the impact energy becomes so intense that the neutrons and protons inside the gold nuclei 'melt'. They release fundamental quarks and gluons that then form a nearly friction-free primordial plasma that only existed in nature for about a millionth of a second after the Big Bang.

"There are many cool things about this ultra-hot matter," says physicist Steven Vigdor, who leads Brookhaven’s nuclear and particle physics program. "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."

Interestingly, though, this phenomenon occurs at both extremes of the temperature spectrum. Similar liquid behavior in trapped atom samples has been observed at temperatures near absolute zero - ten million trillion times colder than the quark-gluon plasma created at the RHIC.

"This is just one among many unexpected connections we’ve found between RHIC physics and other scientific forefronts," says Vigdor. "The unity of physics is a beautiful thing!"

The RHIC may not hold onto its record for very long. The 17-mile Large Hadron Collider (LHC) at Europe’s CERN laboratory carries out similar experiments - and its ALICE experiment may be hitting even higher temperatures - although it hasn't published its figures or had them checked out by Guinness World Records.

"The energy density at the LHC is a factor of three higher than at RHIC," says CERN physicist Despina Hatzifotiadou. "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!"