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What is absolute zero?
The following question was sent to me yesterday:
Can you please tell me what absolute zero means? How can it be that the temperature cannot be below this value? And if there is absolute zero as a lower temperature limit, is there any upper limit?
Yes, indeed absolute zero is the lowest possible temperature a physical body can have. In the degrees Celsius we are used to, this temperature is -273.15 degrees.
What is temperature? It is a quantitative measure of how hot a physical body is. What does temperature depend on? Why do some bodies have a higher temperature and others have a lower temperature? What distinguishes them from each other?
The main difference is the speed of the Brownian motion of the particles that make up a body — atoms and molecules. The faster the molecules and atoms move, the higher the temperature of the body, the slower, the lower. More precisely, the heated bodies have a higher average kinetic energy of the particles that make up the body.
When an object cools down — the average velocity of the particles of which it is composed decreases. Thus, absolute zero is such a hypothetical temperature at which the thermal motion of the particles stops completely.
Why hypothetical? Because such a temperature is unattainable. In order to cool a body to absolute…
