The Arbitrariness Of Temperature Scales

It, therefore, emerges that all temperature scales are random. Each step, from the choice of the thermometric substance and the casing material to the selection of the numbers for the fixed points, emerges to be not related. The result to the question: “which thermometer is accurate” is that it is up to us to call one correct and the other incorrect, for illustration, in figure shown below, when the mercury-in-glass thermometer is taken as standard, then x is the “error” in the alcohol-in-glass reading. Likewise, y is the “error” in the mercury-in-glass reading, when the alcohol-in-glass thermometer is taken as standard.

                                                     Figure: Comparison of Temperature Scales

The other feature about the randomness of temperature scales is that the numbers on the scale are random. There is no extraordinary reason for the numbers given to the ice and steam points on the Fahrenheit and Celsius scales.

Such features cause a severe problem as it means that any temperature measurement is a function of the thermometer employed to measure it. In principle, any thermometer might be standard. Since a practical matter, in order to allow scientists and technologists to know precisely what each other means whenever a temperature is reported, an International Temperature Scale (i.e., ITS) has been determined.