Cryogenics is physics or engineering of low temperature. The temperature is below 150K (-123℃) and down to almost absolute zero. At such a low temperature, everything is calm and the vibration of molecules is quite small. Then you can see basic properties of molecule and nuclei using nuclear magnetic resonance (NMR) etc.. What happen at low temperature? Electrical resistance is very low and some material have no resistance, SUPERCONDUCTIVITY. Some metals will be very brittle and are broken lik