Temperature is a measure of the hotness or coldness of an object. This is why mercury, alcohol, and other liquids increase in a thermometer. The temperature of the liquid rises as it heats up. It expands, so its level goes higher in the tube.

The height of each type of liquid in the thermometer gives temperature readings for various levels. For example, at a freezing point, the level of a liquid might read 0 degrees Celsius (°C) or 32 degrees Fahrenheit (°F).

On the other end of the scale, where it’s boiling at 100 °C or 212 °F, it will be as high as the tube will allow. The liquid goes up and down between these temperatures to show temperature changes.

The thermometer was invented by Galileo Galilei around 1592. This instrument has been used ever since then to measure temperature. This gives us a fundamental overview of what a thermometer is.

In addition, it used to have an essential role in healthcare and other fields. This, however, has been replaced by the electronic thermometer, which is more accurate and less dangerous for children.

The standard temperature in meteorology and science is defined as 0 °C and 32 °F. This is the point at which water freezes, and we can also find the minimum temperature of a daily period frequently. For instance, the standard temperature in chemistry is 25 °C or 298 K.

The melting and boiling points of water are used as zero limits, 273.15 K and 373.15 K at atmospheric pressure, respectively. This means we can’t get temperatures lower than 273 °C or higher than 373 °C in terms of the Kelvin scale.

The Kelvin unit is used in this case because it doesn’t use the limits of the human body as a reference for its values. For example, the Celsius scale or even Fahrenheit scale would be unrealistic considering our body can’t get warmer than 37 °C at standard conditions. This number is more than 100 degrees higher than both of these scales.

On the other hand, it’s also not conceivable to imagine a temperature lower than 273 °C due to the lack of energy for this kind of movement at such low temperatures. Our atoms would be more or less immobile, and we can’t consider their kinetic energies as zero as well as their momentum.

In short, this gives the temperature limits that we observe in our everyday life, and it’s why we can’t directly relate to absolute zero, which is 0 K.