The sun may be the first object that the little pot friends learned to draw. Everything depends on the sun. When you paint flowers and plants, there is always a shining sun in the upper left or right corner! Indeed, even children know that almost all the heat on the earth comes from the sun, which is too important for human beings! < / P > < p > but there is a problem. Many friends may be a little confused. Many movies have such a bridge. For example, when the ebony throat falls into space, it freezes into ice. Why is the earth scorched, but the space between the sun and the earth is extremely cold? < / P > < p > knowing the cold and knowing the heat is the minimum requirement for our partner. Of course, it contains multiple meanings. After all, as long as the human body functions normally, the physical sense of cold and heat is still known. The perception of human body includes temperature, which ensures that we stay away from cold and hot, close to warm and comfortable places, which means the survival and continuation of species! < / P > < p > this answer was once what scientists in the 18th century wanted to understand. At first, they put forward the theory of thermal mass. They thought that thermal mass is a kind of massless gas. After absorbing the thermal mass, the temperature of the object will rise, and the thermal mass will flow from the object with high temperature to the object with low temperature, and it can also pass through the pores of solid or liquid! < p > < p > later, count lenford discovered the heat generated by friction while observing the drilling operation of the cannon, so he put forward the paper. At the same time, the theory of gas movement is also developing. In 1738, Daniel Bernoulli published a book, saying that air pressure is a large number of gas molecules moving around to form pressure, and heat is the kinetic energy of molecular motion! In 1744, romonsov clearly proposed that heat is the expression of molecular irregular motion. In 1859, Maxwell proposed the molecular Maxwell velocity distribution rate on the basis of Clausius’ work. In 1871, Boltzmann extended Maxwell’s work and proposed the Maxwell Boltzmann distribution. However, the theory of molecular motion was still a hypothesis until the publication of Einstein’s Brown motion paper in 1905! < / P > < p > we now know that temperature is the result of the movement of microscopic particles. Of course, with the development of quantum mechanics, there are more essential explanations for temperature. After an object gets hotter and hotter, we will see that it turns dark red. If we continue to heat, we will see red light, white light and even blue violet light. In fact, this is the difference of thermal radiation band! After absorbing energy and jumping to a higher orbit, the extranuclear electrons will fall back to the original orbit due to instability. This process will release light radiation of different frequencies. At low temperature, the thermal radiation band is longer, and the infrared or red light is emitted. When the energy is high, the wave band is shorter, and white or even blue light is emitted. Of course, ultraviolet and X-ray can also be obtained by continuous heating Etc. < / P > < p > temperature is the result of the motion of micro particles, so there will be two corollaries. If the micro particles are absolutely stationary, the object will show the lowest temperature, which is absolute zero. If expressed in centigrade, it will be – 273.15 ℃, but the universe will never reach this temperature, even if the future heat death! So when the velocity of microscopic particles reaches the speed of light, this temperature is Planck temperature! < / P > < p > because special relativity tells us that particles can’t move faster than the speed of light, and we can’t reach this speed. Only at the moment of the big bang, the temperature may be the same. The universe has reached it, but we don’t know how long it lasts, because there will be no time to measure it! < / P > < p > let’s first briefly understand the several ways of temperature transfer, including conduction, convection and radiation, while the sun and the earth can only transfer through radiation. After understanding the nature of temperature, we can analyze why the lower space is cold! < / P > < p > the essence of temperature is the movement of micro particles, so temperature needs a carrier, that is, the micro particle movement of matter. In space, theoretically, it is vacuum, so there is no so-called micro particles. Therefore, it is unreasonable to use temperature to describe pure space! However, in the space of the solar system, there are still a lot of cosmic dust, and there are also a lot of high-energy protons driven by the sun’s radiation. However, these are not comparable to the molecules in the air on earth, which are N orders of magnitude less than those in the air. Therefore, we can draw a conclusion that the temperature of particles in space is very high because they will be exposed to sunlight But they can’t show the macro temperature, because the total amount is too small, like the earth’s atmosphere, the temperature is very high, but it is still very cold! < / P > < p > a region without microscopic particles cannot be measured by temperature, which we have explained above! But the human body still freezes in space. What’s going on? < / P > < p > this is because space is the basic vacuum. The human body has water. Under vacuum, the rapid evaporation of water will take away a large amount of heat, and the final temperature will rapidly drop below the freezing point. Of course, the side facing the sun will absorb solar radiation, which may appear burnt black. With the loss of water and strong radiation, the skin will be burnt! < / P > < p > another reason is that radiation can also dissipate heat. If a piece of iron is thrown in space, it has no water and can not be cooled by evaporation. If there is no solar radiation to give it energy, it will gradually radiate energy around, until it is consistent with the cosmic microwave background radiation, because in the empty space, there is also microwave background radiation shining on it, about 725k, so the iron will not reach absolute zero! < p > < p > the sun is a yellow dwarf star, and its luminous principle is hydrogen fusion in the center! Before the discovery of nuclear fusion in the 20th century, even scientists didn’t know why the sun glowed, so they put forward many lovely hypotheses, such as burning coal, or gravitational contraction, or asteroid impact! < p > < p > in 1920, edinton proposed that the sun may obtain energy from the process of light nuclear aggregation. Later, Gamov solved the theoretical breakthrough that protium and protium in the mass of the sun could be polymerized into deuterium through quantum tunneling effect, and then nuclear fusion took place. After that, Hans bate solved the proton chain reaction and the carbon nitrogen oxygen cycle. Therefore, by the 1940s, scientists were basically engaged in Understand the reason why the sun shines! Because the temperature is not enough for a yellow dwarf star like the sun, when the helium element in the center accumulates to a certain degree, it will suddenly burn and cause helium flash. In the future, with the increase of central temperature, the burning speed will increase and expand. This is the reason for the future red giant star. In the end, it may swallow the earth, but before it swallows the earth, the strong light radiation will burn the earth into a fireball ! Continue Readinggather and watch! Huawei P40 Pro evaluation: excellent mobile phone photography elegant design, do you like it?