The Kelvin temperature scale, developed by William Thompson, Lord Kelvin (1824-1907), in 1848, is widely used by scientists throughout the world. Absolute zero is the temperature at which thermal energy is at a minimum. Each division in the Kelvin scale, called a kelvin (K) is equal to a degree on the Celsius scale, but the difference is where zero is. In the Celsius scale, 0° is the freezing point of water while in the Kelvin scale, the zero point is at absolute zero. Therefore, 0°K is equal to –273.15°C; 0°C is equal to 273.15 kelvins. The Kelvin scale is used for very low or very high temperatures when water is not involved.