Changes

Universally Celsius is the predominant system but Fahrenheit still holds sway in the USA.

Universally Celsius is the predominant system but Fahrenheit still holds sway in the USA.

An alternative scale, the [[Kelvin]] scale (after the famous Irish-born physicist), is used in scientific and engineering circles. It is a [[thermodynamic (absolute) temperature]] scale: it sets 0 K at the '''absolute zero''': the coldest possible temperature in the universe, where an object has no thermal energy. The unit of the Kelvin scale (K) is equal to the unit of the Celsius scale (°C). Thus the freezing point of water at normal atmospheric pressure occurs at 273.15 K.

An alternative scale, the [[Kelvin]] scale (after the famous Irish-born physicist), is used in scientific and engineering circles. It is a [[Absolute temperature scale]] scale: it sets 0 K at the '''absolute zero''': the coldest possible temperature in the universe, where an object has no thermal energy. The unit of the Kelvin scale (K) is equal to the unit of the Celsius scale (°C). Thus the freezing point of water at normal atmospheric pressure occurs at 273.15 K.

The Kelvin is one of the fundamental seven [[SI]] units. Today the [[Kelvin]] scale is defined by two points: the absolute zero and the [[triple point]] of water (273.16 K). No degree symbol (°) is used with the Kelvin symbol (K).

The Kelvin is one of the fundamental seven [[SI]] units. Today the [[Kelvin]] scale is defined by two points: the absolute zero and the [[triple point]] of water (273.16 K). No degree symbol (°) is used with the Kelvin symbol (K).