The extreme temperature zone is all about energy; temperature is energy, and a high temperature particle will have a lot of energy!
There is a lot of research goes into extreme temperature. There are scientists working on the amazing properties of super-cold magnets, and how the world works at very very low temperatures; where molecules have almost no energy. There are biologists looking at “extremophiles”, creatures which can live in environments either far too hot, or far too cold for almost all other species.
Temperature is normally measured in Kelvin (K). It is not theoretically possible to reach 0 K (-237.15 °C), as at this temperature all atoms would stop moving completely. A group of scientists in Italy recently managed to cool a cubic meter of copper to -273.144 °C, very close to the theoretical limit. This is thought to have been the coldest cubic meter in the known universe, as similar conditions are not thought to be possible in nature.
At the other end of the scale, the temperature on the surface of the sun is approximately 5,500 °C, while the highest possible temperature is thought to be the Planck Temperature, around 100 million million milllion million million degrees.
In this zone there are scientists studying neutrinos, tiny particles which travel through the cosmos, and others using high energy x-rays to look at the insides of everything from liquid metals to archaeological remains, and looking at rocks and recreating miniature volcanoes. There is a scientist researching superconductors, and another who is simulating wind from the Sun.