Scientists use the Kelvin temperature scale because it makes solving physics, astronomy and chemistry equations easier, since it lacks negative numbers. Zero Kelvin, the lowest temperature on the Kelvin scale, is especially useful in the field of thermodynamics.
The relationship between pressure, work and temperature is easier to see if a zero point is established. Absolute zero is, theoretically, the lowest temperature possible; it is defined as the temperature at which matter has zero energy. Laboratories have achieved temperatures within one-millionth of a Kelvin. The Kelvin scale is convenient to describe such cold temperatures, because the lower limit on temperature is zero, rather than a large negative number.