Until the day when human civilization collapsed, we couldn't achieve interstellar sailing?

The following article comes from WeChat public account: Global Science, author Global Science

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The probability of existence of extraterrestrial civilization in the universe is far greater than that of earth civilization is the only probability of civilization in the universe. In this case, why did we not find exact evidence of any out -of -local civilization? Some scientists have explained that all civilizations born in the universe may inevitably collapse before developing interstellar navigation technology ...

Our earth is just a corner of the universe, so it is vast and long in the universe. There is also the probability of civilization in other parts of the universe. It is greater than that of civilization in the earth. In this case, are the alien civilizations? Why have we not observed exact evidence of their existence so far?

Not just a science fiction writer cares about this issue, it is also a serious scientific issue. This issue was first proposed by physicist ENRICO Fermi in 1950. He also tried to use rough calculations to indicate that alien civilization had visited the earth. Fermi advocates tens of billions of stars similar to the sun in the Milky Way, which is likely to have livable planets around them. In such a huge number, even if the probability of civilization is very small, the number of civilizations may still be considerable. These civilizations may have developed hundreds of millions of years. Once the resources of their star system are exhausted, Star Immigrants must be performed. It stands to reason that there should be traces of civilized immigrants in the universe, but why have we not observed any evidence so far? This issue was later called "Fermi Paradox".

After the Fermi paradox proposed, some scientists hope to quantify the possibility of alien civilization. In 1961, astronomer Frank Drake proposed a formula to estimate the number of civilizations that can communicate with us in the Milky Way. This formula involves the speed of formation of stars in the galaxy, the proportion of stars has the planet, the planet's life and the proportion of development into civilization. The values ​​of some items can be given by astronomical observation, while others can only estimate. In the end, the conclusion given by Drake based on this formula is that the number of civilizations that can communicate with us in the galaxy can be between 1,000 to 100 million. However, we did not receive any signal of a civilization. How should we explain?

Big filter

The explanation of Fermi paradox can be divided into two categories: either other civilization exists, but they are unwilling to communicate with us for some reason, or there is no civilization except for the civilization of the earth.

The first explanation is the sources of inspiration for many science fiction novels. For example, in the background setting of "Three Body", the exchanges between the universe Chinese and civilized will recruit destruction. Signal. Of course, the development level of different civilizations may be too large to communicate. Perhaps from the perspective of high civilization, the signal issued by the earth's civilization seems to be like the ant in our eyes, and it does not attract their interest in replying.

Image source: UNSPLASH

The latter explanation seems to be more traceable. If the earth civilization is the only civilization in the current stage of the universe, then we are the first batch of wisdom to look up at the starry sky, and naturally we will not receive a signal of other civilizations. And one question that needs to be answered is that there are so many planets that are suitable for the birth of civilization in the universe. Why do humans become the first batch of civilizations? Some scientists have proposed the "The Great Filter" hypothesis, and claim that there are some key links in the process of birth smart civilization, which is seriously underestimated by us. These links play a role in a filter. Even if the universe has been born in the past many lives or primary civilizations, they have not been able to continue to develop through these links.

The big filter hypothesis was proposed by Robin Hanson that he believed that life from birth to interstellar expansion must go through 9 links, including the formation of single -cell life, multi -cell life, and developing large brain capacity. Use tools and so on. Human civilization is currently over the eighth link, and the ninth link is interstellar expansion. Hansen believes that at least one of these 9 links is very difficult to leapfrog, thus filtering out many potential civilizations. If this link is located among the top 8, then humans can relieve it. Maybe we have spent the most difficult stage, and we may go to space in the future. And if this link is the 9th link, then the future of human beings may not be so wonderful: maybe until the day when human civilization is destroyed, we will not develop interstellar navigation technology.

Will civilization crash?

Recently published a study in the "Royal Society Interface Magazine" that supports the filter in the 9th link. From the perspective of the two authors of the dissertation, the civilization born in the universe is likely to collapse because of the explosion of the population before developing interstellar navigation technology.

The two authors quoted a study of LUís Bettencourt and others on the laws of urban growth to infer the evolutionary history of the universe. Studies by Beidu and others pointed out that the energy consumption and wealth creation of cities can be regarded as a power function of the population scale, which is a bit like the relationship between the metabolic rate and volume of the organism. But the difference is that the latter power function index is less than 1, which means that the larger the size of the organism, the lower the metabolic rate; and the index of the previous power function is greater than 1, that is, the more urban population, the more the city's population, the city's population, and the city's city. The higher the "metabolic rate". Based on this law, Bei Danggu and others proposed the equation to describe the evolution of urban population.

In the equation, N represents the population, Y0 represents the total population of the city's population, R is the demand for per capita resource, E is the newly added resource required for the new, and β is the index of the city's "metabolic rate" with the change of population power.

Formula involves parameters such as urban total resource needs and per capita resources. They found that as long as the urban metabolic rate of the power of the population is greater than 1, the population scale will always rise quickly after a period of stable growth. In order to prevent the urban population from collapse too much, people need to propose "innovative technology" every time, which improves the efficiency of resource utilization, which is equivalent to adjusting the parameters of the equation and transitioning to the next stage of a stable growth. However, unfortunately, the window period for humans to adjust to humans is getting shorter and shorter. When the speed of human innovation cannot keep up with the speed of the population, the urban population will still collapse.

Under the description of Beidang ancient equations, the city's population changes with time. After a period of stable population, it will always become infinite after a period of time, and the time window for humans to adjust is becoming shorter and shorter. (Image source: Original Thesis)

The two authors of this study believe that Beidong's urban research conclusions can be promoted to the cosmic civilization. Since the first day of the birth of civilization, it will constantly fight against the spontaneous explosion of population explosion and collapse. And this law leads to the window period for the development of interstellar navigation technology to the development of interstellar development. The two authors take human as examples. If the appearance of written language is the starting point of human civilization, less than 10,000 years later, humans will face technology in less than 10,000 years. The speed of innovation cannot keep up with the dilemma of population explosion. For the long -term continuation of civilization, the author suggested that civilization in the universe should not spend time in developing interstellar immigration technology, but to study how to maintain the population at a stable scale, so that there is no need for interstellar immigrants.

If the argument of this article is credible, then various civilizations including humans, before the 9th stage of the pseudo -crossed filter, may have collapsed due to the explosion of the population. The various civilizations born in the universe have disappeared on the mother star before they have time to develop interstellar navigation technology.

However, can Banggu's law about the size of the city really applies to an alien civilization with great differences in form? Even how universality is this urban evolution law, it is also very problematic. Why can't it be assumed that after the evolution of civilization is evolved to a certain stage, it can get rid of the law of continuous population explosion. Intersection Perhaps than answering the Fermi paradox, this research is more like providing new ideas for science fiction novelists. If human civilization will also face the fate of collapse less than 10,000 years later, it is better to use their imagination to speculate what humans can rely on what ways can continue to save.

references:

https://royalsocietypublishing.org/doi/10.1098/rsif.20222.0029

https://www.pnas.org/doi/full/10.1073/pnas.0610172104

This article is authorized to reprint from WeChat public account: Global Science (ID: huanqiukexue) Author: Bai Defan

Reprinted content only represents the author's point of view

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It does not represent the high energy office of the Chinese Academy of Sciences

Edit: 3C 273

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