Kelvin (K)
Definition: Kelvin (symbol: K) is the SI base unit of thermodynamic temperature. It uses the same degree size as Celsius but starts at absolute zero, the theoretical lowest possible temperature, which is 0 K (equivalent to -273.15 °C).
History/origin: Named after the British physicist William Thomson, 1st Baron Kelvin, who first proposed the absolute temperature scale in 1848. Unlike Celsius and Fahrenheit, Kelvin has no negative values, making it the natural scale for thermodynamic calculations.
Current use: Kelvin is used primarily in science and engineering, particularly in physics, chemistry, astrophysics, and cryogenics. It is the standard for expressing temperatures in scientific literature. Room temperature is approximately 293-295 K.
