Degree (temperature) temperature: (Measurement of temperature) "Degrees Kelvin" (K) is a former name for the SI unit of temperature on the thermodynamic (absolute) temperature scale. Since 1967 it has been known simply as the kelvin, with symbol K (without a degree symbol). Degree absolute (°A) is obsolete terminology, often referring specifically to the kelvin but sometimes the degree Rankine as well. Degree (temperature) The term degree is used in several scales of temperature. The symbol ° is usually used, followed by the initial letter of the unit, for example “°C” for degree(s) Celsius. A degree can be defined as a set change
Absolute zero −273 °C, at almost precisely the same point as the zero of the air-thermometer. This value was not immediately accepted; values ranging from to , derived from laboratory measurements and observations of astronomical refraction, remained in use in the early 20th century. With a better theoretical understanding of absolute zero, scientists were eager to reach this temperature in the lab. By 1845, Michael Faraday had managed to liquefy most gases then known to exist, and reached a new record for lowest temperatures by reaching . Faraday believed that certain gases, such as oxygen, nitrogen, and hydrogen, were permanent gases and