Be cold, be a little cold.

Each of us has the concept of temperature. We know that hot things are high in temperature and cold in things are low in temperature. But besides, what else can temperature tell us?

In fact, when we feel that the object is hot, the atoms inside it move more rapidly, and when we feel cold, the movement is slower. Our bodies turn the speed of this disorder into a sense of heat and cold, and the thermometer is used to express the speed of this movement by numerical value.

So when we heat an object, it is actually moving the atoms in the body faster. For solids, the random motion of atoms is a reciprocating vibration, and for gas, the atom behaves like a ball, flying around. These atoms are constantly colliding with other atoms around, so some fly fast and others fly slowly. Is temperature changing and fluctuate? Unable. Because for a group of atoms, the velocity of each atom varies within a range, but their average speed is constant. If an atom slows down, there must be an increase in the speed of another atom. Therefore, temperature actually describes the average velocity of a whole atom composed of many atoms. Unlike most people, physicists prefer to use a temperature scale different from the Celsius temperature used in our daily life. This is called absolute temperature, and the unit is K. The absolute temperature of 1 degrees is the same as that of Celsius. The difference is only in the selection of zero.

If you keep lowering the temperature of the gas atoms in a box, these atoms will eventually cease to move. This is the minimum temperature limit that an atom can achieve, which we call absolute zero (0k). If there is a thermometer with absolute temperature and Celsius temperature at the same time, the Celsius temperature corresponding to absolute zero is minus 273.15 degrees (273.1 degrees Celsius).

Is there a temperature in the world that is absolutely zero? In fact, outer space should be the coldest place in nature, but the temperature there is also 3k, which is 3 degrees higher than absolute zero. This is a powerful evidence of the big bang that has ever happened. (the prevailing view is that the background radiation originated in the early days of the thermal universe. The measured results of 3K microwave background radiation generally coincide with theoretical predictions). And humans do better in refrigeration than in nature. Scientists can create a refrigeration system that can reduce the temperature of an object by 3K almost a century ago. Then a big leap has reduced the temperature to 1/1000 (10 ^-3 ) Connell and weman reduced the temperature of a very small sample to 1/1000000000 (10). ^-9 This marked a step forward for mankind in refrigeration technology.