Temperature is, in layman’s term, a measure of hotness or coldness of a body or a thing. However, this definition is very subjective since the sensation of hotness or coldness entirely depends on the person’s sensitivity. Scientists needed to quantify temperature due to its relative importance in different disciplines such as medicine, engineering and chemistry.

Early temperature scales were based on the boiling point of water. Celsius created a system which has a decimal relationship in its calibration. Fahrenheit created a similar scale but of a larger calibration between freezing and boiling points of water. The SI unit accepted for temperature, however, is Kelvin named after William Thompson (Lord Kelvin). It has its minimum value (zero) at the theoretical minimum temperature that any object can reach, also called as the absolute zero. It is theorized that at absolute zero, atomic sub particles such as electron that still moves even if the substance it forms is a solid, finally stops moving. At temperatures near absolute zero, substances exhibit superconductivity even if at room temperature they act as insulators. This characteristic could only mean one thing, the molecular motion in the substance is actually slowing down. Absolute zero is theoretically -273.15°C and at best, temperatures of liquid helium and hydrogen manage to about -270°C.