The hottest place in the Universe exists here on Earth, like the coldest place in the Universe. Both these extreme temperatures are not natural, they are human-made. The coldest temperature was achieved in the German physicist and professor of physics Wolfgang Ketterle’s laboratory at the Massachusetts Institute of Technology (MIT). The hottest temperature, also recognized by the Guinness Book of World Records, was achieved at CERN’s Large Hadron Collider (LHC).
On 13 August 2012 scientists at CERN’s Large Hadron Collider, Geneva, Switzerland, announced that they had achieved temperatures of over 5 trillion K and perhaps as high as 5.5 trillion K (more than 9.9 trillion °F). The team had been using the ALICE experiment to smash together lead ions at 99% of the speed of light to create a quark-gluon plasma – an exotic state of matter believed to have filled the universe just after the Big Bang.
For comparison, after a supernova, a newly formed neutron core has an initial temperature of about 100 billion kelvin, 6000 times the temperature of the Sun’s core. The record temperature that achieved at the LHC is around 5000-5500 times hotter than that! Or about 30-33 million times hotter than that of the Sun’s core!
Can we get any hotter than that?
Theoretically, yes. In the Planck temperature scale, 0 is absolute zero, which is taken as −273.15° on the Celsius scale (−459.67° F), 1 is the Planck temperature, and every other temperature is a decimal of it. Contemporary models of physical cosmology postulate that the maximum temperature should be 1.416833(85) x 1032 Kelvin degrees, and at temperatures above it, the laws of physics just cease to exist.
The possible maximum temperature also has a name, the “absolute hot” – a concept has been popularized by the American popular science television series Nova.
Another theory of absolute hot is based on the Hagedorn temperature. It is the temperature in theoretical physics where hadronic matter (i.e. ordinary matter) is no longer stable. For hadrons, the Hagedorn temperature is 2 x 1012 K, which has been reached and exceeded in LHC and RHIC experiments. However, in string theory, a separate Hagedorn temperature can be defined, where strings similarly provide the extra degrees of freedom. But, it is so high (1030K) that no current or foreseeable experiment can reach it.