Many of us think we can measure the temperature of things around us. But that’s not entirely true. In this article, let’s try to figure out so what’s the catch, and what do we actually feel?
The temperature of ordinary things is a measure of the average speed of motion of the atoms and molecules that make them up. The greater the average velocity of the atoms and molecules that make up an object, the higher its temperature. It seems to us that there is a clear correlation: if something has a high temperature, it seems hot to us and vice versa. Thus, we perceive our sensations as very precise measurements. However, this is not entirely true.
If you touch a piece of metal or a book that has just been taken out of the freezer, the metal will seem much colder than the book. The metal and the book will have the same temperature, but the metal will seem much colder.
Metal is a substance that conducts heat very well, quickly “takes it away” from warmer bodies, and quickly “gives” heat to objects that are colder than metal. Paper, on the other hand, is the opposite; it conducts heat poorly, “gives” and “takes away” it slowly. Even though metal and a book have the same temperature, the movement of molecules in our hands is absorbed much faster by metal than by paper. The metal causes the temperature of our hands to drop faster, which makes us feel like the metal is colder. What we actually feel is the temperature of our hands. Our internal thermometer only measures its own temperature (just like any other thermometer, by the way). You can tactilely measure the temperature of other things by making sure they are in contact with your skin. The thermosensitive nerves in our skin can only directly measure the temperature of the skin itself. When we touch something, we don’t feel its temperature, but only the effect of the object on our skin.
The cloud of steam from your pot seems much hotter than the hot, dry air from the oven, which actually has a higher temperature. Steam carries a lot more molecular motion to your skin than air does. You could say that hot and cold are concepts that are fundamentally different from the concept of high and low temperature. A hot object is an object that gives off a lot of energy, a cold object is an object that gives off little energy. Indeed, when someone has a lot of something, it does not mean that he gives a lot away.