Among the different fundamental units, Kelvin, or the unit for temperature, is the one I am going to talk about.
Kelvin was named after its originator, Lord William Thomson Kelvin. He was a Scottish mathematician and physicist, who contributed to many branches of physics. He argued about the Law of Thermodyanamics that if the entropy (a thermodynamic quantity representing the unavailability of a system’s thermal energy for conversion into mechanical work) always increases, then the universe would eventually reach a state of uniform temperature and maximum entropy from which it would not be possible to extract any work. He called this the Heat Death of the Universe.
In the mid-1800s, the Kelvin temperature scale was developed. Lord Kelvin developed this with the help of a Carnot engine. The Carnot engine deals with the relationship between pressure, work, and temperature. The Carnot engine is the most efficient engine possible, however it cannot reach 100% efficiency. If an engine was 100% efficient, no energy would be wasted. The Carnot engine is only theoretical, which means that all real engines are even less efficient.
The zero point on the Kelvin scale is base on the point at which the pressure of all dilute gases mathematically project to zero from the triple point of water. The zero point of this scale is equivalent to -273.15 °C on the Celsius scale. This zero point is considered the lowest possible temperature of anything in the universe. Therefore, the Kelvin scale is also known as the “absolute temperature scale”. At the freezing point of water, the temperature of the Kelvin scale reads 273 K. At the boiling point of water, it reads 373 K.