Why Isn't Kelvin the Only Temperature Measurement Used?

When it comes to measuring temperature, we often use the Celsius scale, which is widely recognized and utilized in everyday life, particularly in countries like Canada and most of the world. In fact, this scale was originally known as Centigrade and was created by scientist Anders Celsius. However, for various reasons, including ease of use and practicality, Celsius remains a preferred choice over Kelvin, which has a true zero point and is particularly useful in scientific fields.

The Fahrenheit scale, although still used in some countries, has largely been superseded by the Celsius scale. However, it's notable that in the 1960s, Britain made the transition to the Celsius scale to align with international standards. Among all the temperature scales available, such as Kelvin, Fahrenheit, Rankine, Réaumur, and others, the Celsius and Kelvin scales stand out due to their widespread usage and theoretical significance. But why have we not fully embraced the Kelvin scale in our everyday lives?

The Evolution of Temperature Scales

Let's delve into the history of temperature scales. The Celsius scale was originally conceived as an inverted scale, where water boiled at 0 degrees and froze at 100 degrees. This design was later reversed to the standard Celsius scale we use today, where water boils at 100 degrees and freezes at 0 degrees. This reversed design made the scale more user-friendly and relatable, especially for common temperature measurements.

The Kelvin scale, on the other hand, retains the inverted design from Anders Celsius's original scale, but it shifts the zero point to absolute zero, the lowest possible temperature where particles have minimal kinetic energy. This shift makes the Kelvin scale useful in scientific calculations and thermodynamics, but it adds a layer of complexity that makes it less intuitive for everyday use.

The Commonality of Celsius

In Canada and many other countries, the Celsius scale is the primary method of measuring temperature in daily life, from weather reporting to personal thermometers. The simplicity of the Celsius scale, with its relatable zero and 100 points, makes it a perfect fit for everyday use. For example, saying 20°C is twice as hot as 10°C is not accurate in the Kelvin scale, where 20K is not twice as hot as 10K. This misunderstanding and the resulting inaccuracies can make the Kelvin scale less practical for everyday use.

It's important to note that while Celsius is widely used, it is essentially the same as the Kelvin scale in terms of the actual temperature difference. One degree Celsius is the same as one Kelvin. The difference lies in the zero point, with Celsius setting it at the freezing point of water and Kelvin at zero-point absolute.

Why Not Kelvin?

The Kelvin scale's true zero point comes in handy in scientific contexts, particularly in thermodynamics and absolute temperature calculations. However, in everyday life, the Celsius scale offers a much more straightforward and relatable way to express temperature. For instance, saying it's "minus 20 degrees" or "plus 20 degrees" in Celsius is more intuitive than saying it's "283.15 Kelvin" or "243.15 Kelvin."

Furthermore, the practical and psychological appeal of the Celsius scale, with its easy-to-grasp zero and 100 points, makes it a better choice for weather forecasts and personal comfort. The zero point in Celsius corresponds to a freezing temperature that is familiar to most people, making it easier to relate to the concept of temperature.

For example, if a weather report states that the temperature will be 25°C, it's straightforward for the public to visualize and prepare accordingly. If the same temperature were expressed in Kelvin (298.15 K), it would require mental math and a deeper understanding of the Kelvin scale to grasp the same meaning.

Conclusion

In summary, while the Kelvin scale is a valuable tool in scientific and engineering contexts, its complexity and less intuitive zero point make it less practical for everyday use. The Celsius scale, with its familiar zero and 100 points, remains the preferred choice for most people due to its simplicity and relatability. However, the Kelvin scale's true zero point is crucial in certain scientific calculations and remains an essential part of the SI (International System of Units).

Therefore, while Kelvin is indeed a valid temperature measurement, it's not the only scale used due to its complexity and the practical advantages of the Celsius scale in everyday life. Understanding both scales is beneficial, as they each serve important purposes in different contexts.