Hot, Heavy Matter.

Science News reports on the hottest, heaviest science ever to come out of a research lab:

Talk about hot and heavy. Scientists have taken the temperature of a minuscule glob of dense, hot matter formed in the grisly aftermath of collisions between gold atoms traveling near the speed of light. The material reaches an estimated 4 trillion degrees Celsius, about 250,000 times hotter than the sun’s interior, and higher than any temperature ever reached in a laboratory, researchers reported February 15 at a meeting of the American Physical Society.

The measurements, which will be published in an upcoming Physical Review Letters, provide a more detailed description of the superhot, superdense soup of matter called quark-gluon plasma, which may mimic the conditions of the infant universe, the researchers say.

It only lasted a trillionth of a trillionth of a second, so they could only tell how hot it was by how bright it was. They counted photons.