# How long can a person survive in a sealed environment of minus 30 degrees with enough food and clothes

This paper takes part in the series essay competition of “great science” of Recordunkown.

The moment of the big bang, the temperature was born, every corner of the universe will have different temperatures, and the temperature of the whole universe background is as low as minus 270 degrees Celsius. In the universe, the most important source of temperature is the star. Nuclear fusion happens all the time inside the star, and the energy generated diffuses around and is transmitted to various stars, so that different stars have different temperatures.

The earth is a planet in the habitable zone. Due to the appropriate distance, it produces the appropriate temperature. And the appropriate temperature also created the earth this superior hotbed of life, so that the earth has become a life planet. Life on earth is born under the condition of meeting the temperature of the earth. If it is not suitable for this temperature, it will be extinct.

Human beings are the only intelligent life on earth. Their body temperature has reached 37 degrees Celsius, which is a very suitable temperature. Although human beings have a suitable temperature base, because the temperature of the earth’s environment is changing all the time, we can sense the change of temperature, that is, the cold and hot we feel.

Someone once raised such an interesting topic: if a person keeps enough food and clothes in a sealed environment of minus 30 degrees, how long can he survive? Many people may think that as long as they have enough food and warm clothes, they should be able to survive for a very long time in a cold environment.

But is that really the case? In fact, the answer is far more cruel than we think. Human beings are a kind of stellar animals. The reason why we can feel cold and hot is that the internal heat of the human body is different from the speed of the boundary. When the heat generated inside us is greater than the heat dissipation, we will feel hot. If the heat generated inside the human body is less than the heat dissipation, it will feel cold.

So what are the factors that affect the body’s heat dissipation? In fact, it is mainly affected by the external temperature. If the external temperature is far lower than the temperature of the human body, then the temperature of the human body will quickly escape to the outside world. This mode is actually the conductivity of heat, and heat will be transferred from the hot place to the cold place. In the same way, if the temperature of the outside is higher than that of the human body, then the heat from the outside will be transmitted to the human body. If the heat is transmitted too much, it will be harmful to the human body. This is also the reason why people are prone to heatstroke in the high temperature season in summer.

The temperature inside the human body can only maintain a balanced and mild state, so that the human body can keep healthy and feel comfortable. The channel of contact and exchange between the temperature inside the human body and the temperature outside is the skin of the human body. When we put on clothes, with the insulation of clothes, it’s not so easy for the external temperature to reach the skin layer.

At this time, the heat in the human body is not lost so quickly, and we will feel warm instead of cold. Clothes play a role of isolation. When we reach an environment with a temperature as low as minus 30 degrees, the temperature of the outside world is very low, far lower than that of the human body. At this time, according to the principle of heat conduction, the heat of the human body will quickly lose, we will feel colder and colder, and finally endanger our lives.

Only when we put on thick clothes, can we increase the insulation layer. At this time, the external environment can not directly contact with the human skin, and the heat in the human body will not be quickly lost. So that we can maintain a comfortable body temperature, of course, no matter how good measures to keep warm can not guarantee that no heat is emitted. Even if completely isolated from the outside low temperature environment, the body’s heat will continue to lose, the loss of heat is actually the supply of human organs and tissues.

As we all know, the human body is a very complex structure with various organs and components. To maintain the activity of these organs and tissues, we need energy supply. The maintenance of human life function needs heat. According to different parts, the heat consumption is different. The basal metabolic rate accounts for 65-70% of the total heat consumption of the human body. Physical activity accounts for 15-30% of the total heat consumption. Finally, the thermal effect of food accounts for less than 10%.

The body heat mainly comes from the fat, protein and carbohydrates stored in the body, and these substances need to be obtained by the body through food. Therefore, in theory, as long as there is enough food, the human body will not lack of heat and can survive in a cold environment for a long time. Only in an open environment.

If we are in a small sealed environment, the situation is totally different. Even if we have enough food and warm clothes, it is difficult for us to survive for a long time. The reason is that the air in the sealed environment cannot be updated in time. We all know that human beings can not survive without oxygen supply.

Like most organisms, human beings need to breathe oxygen all the time to survive. This is a physiological process. Every time we breathe, we exchange oxygen through the alveoli, expel carbon dioxide. The inhaled oxygen is transported to all parts of the body through the red blood cells to participate in the oxidation process. The carbon dioxide is discharged through the alveoli, and is discharged from the body through the exhalation action of the lungs.

For us, oxygen is a useful and necessary gas, while carbon dioxide is a poisonous gas. If we live in a sealed environment, the amount of oxygen is limited. Every time we breathe, we will reduce the oxygen in the environment and increase the carbon dioxide.

As time goes on, there will be less oxygen and more carbon dioxide in space. At this time, we will not only have a sense of suffocation, breathing more and more difficult, but also carbon dioxide poisoning. Just imagine, at this time, will we still live? Of course not, so even if we have enough food and clothes, we won’t survive for long in a sealed space. A few hours at least, a few days at most.

It may be said that the earth where human beings live is also a limited planetary space? If so, why can we survive all the time? In fact, the limited space of the earth is a complete ecological cycle system, oxygen and carbon dioxide can form a cycle, in which plants play an important role.

The photosynthesis of plants is just opposite to the respiration of human beings. It can convert carbon dioxide into oxygen. Therefore, human beings and plants have a mutually beneficial cooperative relationship. If there are no plants on the earth, then the human crisis will come. Therefore, we should protect the vegetation and the green environment on which human beings depend. Unfortunately, in the past century, with the rapid development of science and technology, people’s damage to plants is very serious.

And the rapid development of industry is also constantly emitting carbon dioxide, making the carbon dioxide in the atmosphere higher and higher. These carbon dioxide can not only aggravate the greenhouse effect, let the earth’s temperature rise, but also make human carbon dioxide poisoning. The reason why we still don’t feel obvious carbon dioxide poisoning is that the carbon dioxide content in the atmosphere has not reached a certain level.

However, the rapid development of industry continues. If we do not have other more effective ways to absorb carbon dioxide, it is possible that in the near future, once the carbon dioxide in the atmosphere breaks through a critical point, human beings may usher in a terrible ecological crisis.