In physics, cryogenics is the study of the production and behaviour of materials at very low temperatures.It is not well-defined at what point on the temperature scale refrigeration ends and cryogenics begins, but scientists assume it starts at or below −150 °C (123 K; −238 °F). The National Institute of Standards and Technology has chosen to consider the field of cryogenics as that involving temperatures below −180 °C or −292.00 °F or 93.15 K.