There's no spoon

Maybe one day you thought: what is temperature? No, really, what does it mean when something is hot or cold? Driven by this strange question you took your measuring devices and started looking very closely at the smaller and smaller parts of matter hoping to find something you can identify as temperature.

At the end of the 19th century the Boltzmann constant “k” was introduced to link the average speed of individual molecules with the overall gas temperature. The temperature was defined to be proportional to the measure of chaos in the system, which corresponds to the molecules speed squared. In short: when gas particles move fast - we say the gas temperature is high. Consequently, the absolute zero happens when molecular movement stops entirely.

Your room is filled with air molecules… at room temperature. Try a mental experiment - start shrinking the size of the room, making it smaller and smaller with fewer and fewer molecules. At some point the room will become so small that only a few molecules can fit inside. Looking at these individual molecules, is it still fair to say that they have a temperature? How about a single molecule?

By looking closely enough you might discover that there's no longer a temperature. The very concept of temperature is not applicable. This is what's known as an emerging phenomenon - it exists only when you look at myriads of tiny agents from a distance, and only when there's someone looking. We are macro organisms living in the world that operates on a microscopic scale. We have to simplify the infinite complexity of zillions of molecules into something we can make sense of - a temperature.

Remember the famous scene in The Matrix where Neo comes to see the Prophet and a kid with a shaved head shows him a spoon saying: "There's no spoon". Well, there's no temperature, literally, there's nothing in the universe that inherently exists and can be called temperature before we humans came to call it that.

Based on a mental experiment from "I'm a strange loop" by Douglas R. Hofstadter.