Which scale is referred to as the absolute Celsius scale?

The Kelvin scale is referred to as the absolute Celsius scale because it is based on the concept of absolute temperature. In the Kelvin scale, zero Kelvin (0 K) represents absolute zero, which is the theoretical point where all molecular motion stops and corresponds to -273.15 degrees Celsius. This scale is crucial in scientific measurements as it allows for thermodynamic calculations without negative values, which can complicate equations. The Kelvin scale maintains the same incremental value as the Celsius scale, meaning that a change of one degree Celsius is equivalent to a change of one Kelvin.

In contrast, other scales such as Fahrenheit and Reaumur do not align with the absolute temperature concept in the same way, as their zero points are arbitrarily defined based on different criteria. The Rankine scale, while also an absolute scale, is based on the Fahrenheit degree rather than the Celsius degree, making the Kelvin scale uniquely aligned with Celsius. This alignment is essential for scientific work, especially in fields like physics and engineering.