... Z Machine Sets Unexpected Earth Temperature Record . ... Credit: Z Machine Collaboration , Sandia National Lab , Lockheed Martin , NNSA, DOE Explanation: Why is this plasma so hot? ... What is known for sure is that the Z Machine running at Sandia National Laboratories created a plasma that was unexpectedly hot. The plasma reached a temperature in excess of two billion Kelvin , making it the hottest thing ever in the history of the Earth and, for a brief time, hotter than the interiors of stars. ...