Because the earth has the conditions for life: suitable temperature, sufficient moisture, and an atmosphere suitable for life. First of all, I agree with upstairs that human beings have not found other life outside the earth because of the limitation of current technology. But in the universe, there are very few lives caused by various reasons. First of all, the formation of life needs organic matter and suitable temperature. Few planets meet these two requirements. Coupled with the lack of technology, it is more difficult to find other life or even highly intelligent life. However, there will definitely be aliens. Scientists have discovered several planets similar to the earth's environment, which can give birth to life. There is only life on earth in the universe? In the galaxy1800 million planetary system, if 1% of the galaxies have the possibility of life, then the probability is greater than1800 million; In this1.80 billion, if 1% has living things, then the probability is1.80; 1.8 million, if 1% is an intelligent creature, then the probability is 1.8 million. If you count the galaxies outside the river, the probability will be surprisingly high. So the idea that "man is the only child in the universe" is naive and ridiculous.
Every starry night, we look up at the sky, and a galaxy crosses the sky. The Andromeda Nebula next to Polaris tells people stories that the ears can't hear. At this time, the myth of the Cowherd and the Weaver Girl, the legend of the Goddess Chang'e flying to the moon and the story of the Arctic fairy Weng have already surrounded our hearts. Following the ancient sound of Qu Yuan asking for heaven, we dare to ask the sky: Are there any relatives and friends in the vast expanse?
Are there any creatures in the universe besides stars? Are there any intelligent creatures as great as human beings? The universe did not answer! Is it acquiescence or disdain?
This can't be blamed on the great universe, but only on the small earth people, because before the universe answers, even before we ask questions, we already have a definite answer in our hearts, that is, the earth is the only child of the universe.
The view that the earth is the only seedling in the universe has existed since ancient times. You will not forget that in the Middle Ages, in the West, religious theology believed that the earth was the center of the universe, because Almighty God lived on it. Of course, this is not only a problem in the west, but almost all ethnic groups in the world have similar views. China people think that China is the center of the world, so it is called "China". In fact, everyone knows in their hearts that we are not really praising the greatness of the earth, but in another way to praise the greatness of mankind. "Everything in the world is only people." This is the most fundamental purpose. The concepts of "the earth is the center of the universe" and "man is the only son of the universe" have long been deeply rooted in people's hearts.
It is understandable to say that the above ideas stem from the backwardness of understanding, but the problem is that it seems to have nothing to do with people's understanding. In fact, until today, quite a few people still hold the same view. Modern science seems to have no intention of eliminating the concept of geocentric theory when it overturns superstition. On the contrary, many scientists are actively looking for evidence to prove the religious concept that human beings on earth are the only children in the universe. Therefore, the key lies in the arrogant nature of human beings.
However, no matter how carefully people maintain their fragile self-esteem, the development of science itself is crushing the already riddled self-esteem again and again, and people are being forced to accept the following facts:
Just as we see the world as a whole today, in fact, the whole universe is a perfect whole, and our earth and solar system are only a small part of this whole, which is almost negligible. Similarly, just as the political, economic and cultural development of countries can not be separated from the overall influence of the world, the existence and evolution of galaxies in the universe also influence each other. When our civilization is breaking through the gravity of the earth and moving towards the civilization of the universe, people are increasingly aware that in the whole universe, it is not only human beings who can consciously influence the development of the earth (the history of human influence on the earth is only 2 million years at most, accounting for only 1/2500 of the earth's time), and unexpected things are happening all the time in the vast universe. The birth and destruction of life are indispensable in the operation of the universe.
Let's first look at the probability of life in the universe: modern astronomy recognizes that there are about 300 billion stars in our galaxy, and there are at least 654.38+08 billion planetary systems. If only 654.38+0% of these planetary systems may have life, then this number is still huge, up to 654.38+08 billion. Similarly, if there is life in 1% of these planetary systems, then the number we get is still 1.8 million. Let's further assume that every 100 living planets, only shellfish are inhabited by creatures with the same level of intelligence as humans, so there are still as many as 18000 planets in our galaxy that may have advanced life. This is just our own galaxy. How many giant galaxies like the Milky Way exist in the middle of the universe? I'm afraid this is a terrible astronomical figure.
Therefore, it is naive and ridiculous to think that people on earth are the only intelligent creatures in the universe from the perspective of probability alone. There is no doubt that there are countless planets similar to the earth in the universe, with similar mixed atmosphere, similar gravity, similar plants and even similar animals. As early as the 4th century BC, the ancient Greek philosopher Mitterrand once said, "The idea that only the earth is inhabited in the boundless universe is as ridiculous as a seedling growing on the land where millet was sown."
1997, American biologists discovered an Archaean creature on the earth, which can survive in extremely cold or extremely hot environment. It has two characteristics of bacteria and all eukaryotes, including animals, plants and people, and is the third life form. The discovery of this creature proves that human understanding of life characteristics is not enough. Please don't forget that this is only in the environment of the earth, in the middle of the vast universe, the form of life is more complicated. It is the most undesirable way to evaluate the existence of cosmic creatures from the perspective of geo-biology. Nasa recently announced that it has discovered a new planet orbiting the Porel Lisi star near the earth, which is about the size of Jupiter, the largest planet in the solar system. The newly discovered planet is 37 million kilometers away from the star, which is 1/4 of the distance from the earth to the sun, even closer than the distance from mercury to the sun. Its surface temperature is estimated to reach 200℃-260℃. At this temperature, it is difficult for life on earth to survive, but there may be high-temperature resistant life in the universe. The discovery of this planet has strengthened people's confidence that there are probably a large number of living planets in space.
1969, the right asymmetric amino acids that could not be naturally formed on the earth were found in the carbonaceous chondrite falling in Australia, indicating the possibility of life outside the earth. Just recently, NASA announced that photos taken from the Hubble Space Telescope show that Jupiter, which has always been considered unstable, has been found to have an atmosphere and moist soil, which shows that Jupiter already has the basic conditions for life. 1996, NASA discovered from a Martian meteorite from Arizona, USA that there were ancient microorganisms in this meteorite, and the ancient legend of life on Mars was once again taken seriously.
1963, scientists discovered the spectrum of the organic molecule formaldehyde in Sagittarius with a radio telescope, which is of great significance. Because organic formaldehyde molecules can be converted into amino acids, and amino acids are the basic components of life. The discovery of organic formaldehyde molecules proves once again that life on earth is by no means a unique phenomenon in the universe, and human beings should not be the only child in the universe.
More and more discoveries point out a direction for us: life does exist in the universe, and even the most familiar life forms may be produced in a corner of the universe. The problem now is not to prove the existence of these lives, but to find them.
In 1970s, the United States took the lead in launching "Voyager 1" and "Voyager 2" in order to find possible life forms in the vast universe and have a dialogue with them. At this time, two spaceships are flying into outer space at the speed of 17.2 kilometers per second. 1986, when they passed Pluto, they flew out of the solar system and became real cosmic planets. If nothing happens, they will fly to another galaxy outside the solar system in 6.5438+0.47 million years and 555,000 years respectively.
Voyager has a bronze gold-plated record, which records the characteristics of our earthlings, the face of the earth and the greetings of former US President Carter to alien civilizations. The former president of the United States wrote in his letter: "We send this message to the universe. After 65.438 billion years, when our civilization has undergone profound changes and the face of the earth has undergone tremendous changes, this information may still exist. Among the 300 billion stars in the Milky Way, some (perhaps many) stars and planets are inhabited and there is a distant cosmic civilization. If such a civilization intercepts Voyager and can understand its recorded contents, please accept our following message ... "Obviously, Voyager was launched in search of extraterrestrial civilization. In other words, Americans assume that extraterrestrial civilization exists.
1994, when comet shoemaker-levy hit Jupiter, scientists found that a lot of water vapor appeared during the impact, which indicated that the comet had a lot of solid water. Where there is water, there is life. Comet Shoemaker-Levy is a very common comet in the universe. They travel across the universe, and there is a great possibility of life.
In fact, the problem is not just here. What kind of natural environment does life need? Is it necessary to have natural conditions similar to the earth? Is the biological view of the earth universally applicable to all the planets in the universe? Facts have proved that the view that life can only exist and develop on a planet like the earth is untenable.
There are more than 2 million kinds of living things on the earth. Among the 6,543.8+200,000 known species, there are more than 9,000 kinds of wells that do not need the general natural environment. In his book Car of the Gods, ehrlich Dunken introduced the experiments made by entomologists Hinton and Bloom of Bristol University. The two scientists baked an midge at a high temperature of 100℃ for several hours, immediately put it in liquid nitrogen (temperature is 270℃), and after intense irradiation, they put these experiments back into the normal living environment. These midges quickly regained their vitality and produced healthy offspring. This experiment fully shows that it is wrong to say that life can only exist under the conditions of the earth.
According to the biological viewpoint of the earth, sunlight, moisture and oxygen are the three elements of life. However, people have found creatures that don't need sunlight and bacteria that don't need oxygen under the seabed and the Arctic ice. They are called anaerobic bacteria. Many years ago, it was reported that people found frogs that had been sleeping for tens of thousands of years from completely closed rock formations. Under normal natural conditions, they actually regained their vitality. Life is incredible. Its tenacity is beyond people's imagination. With the deepening of our understanding, we found many lives in completely unexpected environments. For example, there is life around highly radioactive nuclear materials.
Now, more and more people believe in the existence of "extraterrestrial civilization", and they are likely to evolve dozens or even hundreds of times earlier than us. Today, we can not only land on the moon, but also explore the whole solar system. Then, a civilization many times more developed than ours, it is entirely possible for them to explore across galaxies, leave some remains and impart some knowledge in contact with our ancestors. Under this thought, the "ancient contact theory" came into being.
The founder of ancient contact theory is Ford Childs Hou of the United States. Throughout his life, he tirelessly collected data and information that could overthrow popular theories and put forward the slogan "Let science be liberated from the monopoly of scientists". His basic idea is that there are huge creatures in the universe, and for these creatures, the size of our world is only between the feeding box and the laboratory. He even said, "I guess we are the private property of some creatures." I think the earth originally didn't belong to anyone, and later it was investigated as a colony. " Why are there so many planets in the universe that only the earth can use the universe (Coriolis cosmology)
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Modern astronomy believes that the universe is the sum of all matter in time and space, [1] is the whole of our material world, and it is the biggest research object of physics and astronomy. The scientific methods and theories to explain the universe constitute cosmology with modern significance. Today, cosmology has become an exact science. [2]
The ancient definition of the universe is Huainanzi in the Western Han Dynasty: "The past is called the universe, and the four sides are called the universe." [3]
Through the observation of cosmic microwave background radiation, it is found that our universe has expanded by 65.438+0.382 billion years, but the diameter of the universe is obviously larger than this value. The latest research thinks that the diameter of the universe can reach 92 billion light years, or even more. [4]
Some objects in the universe observed by human beings are composed of about 4.9% ordinary substances (substances that make up stars, planets, gases and dust) or baryons, 26.8% dark matter and 68.3% dark energy. Baryon matter forms a "spider web" between galaxies [5-6]
In the universe, the earth is the only living planet known to mankind.
BIGBANG is a cosmological model that describes the initial conditions for the birth of the universe and its subsequent evolution. This model is supported by the most extensive and accurate scientific research and observation. Cosmologists usually refer to the view of the Big Bang: the universe evolved from an initial state of extremely high density and extremely high temperature a finite time ago, and reached its present state through continuous expansion. [7]
Dark matter and dark energy show their existence by exerting gravity on ordinary matter and accelerating the expansion of the universe respectively. If dark energy does not exist, then the gravitational force between substances will slow down the expansion of the universe, but astronomical observations show that our universe is accelerating. [8] There is only life on earth in the universe. Are there really aliens? This is still a mystery! Although there is no definitive evidence yet, I believe there must be other life in the vast universe!
I'm not just guessing! The universe is big, and there is no wonder! Although a life needs many conditions, it is not impossible. Isn't the earth an example? There are countless planets like the earth in the universe. Is there life only on the earth?
Even if all life needs water, there is more than one planet with water! At present, only planets with liquid water have not been found in the solar system. There are many galaxies as big as the Milky Way in the universe, and countless others like the solar system! Still afraid of not finding a second earth?
Although we can't find aliens yet, won't more advanced aliens come to us? So far, many things similar to alien spacecraft have been recorded by people. They are collectively called UFOs. Although 99% of UFOs are masterpieces of nature, are there still unconfirmed ones? Aren't they alien spacecraft?
To sum up, alien life must exist! I just haven't found it yet
A few days ago, after scientific calculation, the planets and star systems in the Milky Way are similar to the earth-sun. According to research, there are about 1% stars of the same type as the sun in the Milky Way, among which at least 10% stars have planets, that is, 1 100 million stars have planets like the sun.
So it will definitely be discovered in the future. Is there only life on earth in the universe? No, a lot. We just haven't found it yet. Why is the universe so big that only life exists on the earth? Not necessarily, because the universe is so big, there are infinite possibilities. It is not necessarily only the earth that has life. Is there only life on earth in the universe? No, there are many galaxies in the universe. We only live in one galaxy. There must be many other galaxies similar to ours, but we just don't know it yet. There is life in the universe besides the earth. Is there life on other planets 1? The answer is yes, but it has not been discovered yet. From the perspective of life evolution, the earth was born only 4.5 billion years ago, so the life on the earth evolved for 4.5 billion years at most. Then, there are many planets in the vast universe that are older than the earth and suitable for the evolution of life. It has been calculated that there are about 3 billion galaxies in the universe (galaxies similar to the Milky Way, large and small), and each galaxy has about 1000 planets suitable for life. The birth of life is based on organic matter, which at least consists of oxygen, nitrogen, hydrogen, carbon and other elements. Then, there must be many planets with these elements in the universe. As long as there are suitable conditions, these elements can be combined into organic matter, and then these organic matters continue to evolve, eventually leading to the birth of life. Take the life evolution of the earth as an example: oxygen, nitrogen, hydrogen, carbon and other elements on the earth formed the protein under the action of solar ultraviolet rays and thunderstorms; Coincidentally, the distance between the earth and the sun is just right, so there is life. Then life further evolved under the constraints of the environment. Then, after n hundred million years of evolution, human beings came into being. There are trillions of planets in the universe. Therefore, if we find a geographical condition similar to the earth in the universe, there will definitely be several. Therefore, it cannot be said that there is no life form except the earth.