Temperature for zero temperature, according to the third law of thermodynamics. Nevertheless, a Kelvin temperature does in fact have a definite numerical value that has been arbitrarily chosen by tradition and is dependent on the property of a particular materials; it is simply less arbitrary than relative "degrees" scales such as Celsius and Fahrenheit. Being an absolute scale with one fixed point (zero), there is only one degree of freedom left to arbitrary choice, rather than two as in relative scales. For the Kelvin scale in modern times, this choice of convention is made to be that of setting the gas–liquid–solid
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