What would scientists need kelvins to measure?

Answer 1

The kelvin (symbol: K) is a unit increment of temperature and is one of the seven SI base units. The Kelvin scale is a thermodynamic (absolute) temperature scale referenced to absolute zero, the absence of all thermal energy. So by definition, the temperature of a substance at absolute zero is zero kelvin (0 K). The secondary reference point on the Kelvin scale is the triple point of water (0.01 degrees Celsius). The Kelvin scale is the difference between these two reference points, with the kelvin defined as one 273.16th of this scale. The Kelvin scale and the kelvin are named after the Belfast-born physicist and engineer William Thomson, 1st Baron Kelvin (1824-1907), who wrote of the need for an "absolute thermometric scale". Unlike the degree Fahrenheit and degree Celsius, the kelvin is not referred to as a "degree", nor is it typeset with a degree symbol; that is, it is written K and not °K. The kelvin and the degree Celsius are often used together, as they have the same interval, and 0 kelvin is −273.15 degrees Celsius.

short answer - temperature.

Kelvin is the absolute temperature scale, with the same size degree as Celsius, but with zero set at 'absolute zero' - the temperature you can't go lower than...