Can you imagine a world without the sun? Astronomers’ research shows that if there is no sun, the average surface temperature of the earth will drop to below-17.78 degrees Celsius in a week, and it will drop to-73.33 degrees Celsius in a year. Most plants will die in a few weeks, and then most life will disappear because of the disappearance of the sun, and everything will be dead.
Now we know how important the sun is to us! However, something unfortunate happened. Recently, foreign scientists’ research on the metal abundance of the sun shows that we may overestimate the life of the sun by one billion years, and the sun may die one billion years earlier than we expected.
Elemental abundance controls the sun’s life gate
It is understood that scientists have previously deduced that the life of the sun is about 10 billion years based on the standard solar model that ignores the rotation effect, which is a theoretical value simulated by the stellar evolution program, not a real value. And this value only refers to the central hydrogen combustion life in the theory of star evolution.
"This is not to say that the sun really can only exist for 10 billion years. The accurate statement should be called the main sequence life of the solar model. In theory, the sun will become a red giant in about 10 billion years, but it still exists and will emit more sunlight. " Associate Professor Yang Wuming from the Astronomy Department of Beijing Normal University told the Science and Technology Daily reporter.
He said that there are many preconditions to get the theoretical value of 10 billion years, and it is necessary to assume the initial element abundance of the sun and the physical process inside the sun. The life of the solar model is different with different initial element abundances. Because it is impossible to really get the initial element abundance of the sun and determine its internal physical processes, the life of the sun and even other stars cannot be accurately estimated.
Twenty years ago, astronomers’ direct and indirect measurements of the sun showed that the metal abundance of the sun was around 1.8%; However, the latest solar spectrum measurement shows that the metal abundance of the sun is only 1.3%, which is far lower than the previous measurement results, and correspondingly, the life of the sun will be reduced by 1 billion years.
The so-called solar metal abundance is the general term for the abundance of solar elements except hydrogen and helium. This metal is different from what we usually call metals. Because the contents of hydrogen and helium in the sun account for the vast majority, astronomers call all the heavier elements in the sun "metals". Although the content of these metals is small, it affects the fate of the sun.
Because the electrons of metal elements easily absorb photons, which hinders radiation, the higher the metal abundance of the sun or star, the higher the opacity. The opacity of the sun or star is closely related to its life, temperature, brightness and other properties. Sani Vaniotch, a physicist who studies solar metal abundance at Stockholm University in Sweden, said that a very small amount of metal is enough to completely change the behavior of a star, and metal abundance can basically tell you how the star will die.
Influence of atmospheric model on solar lifetime estimation
The solar spectral measurement used in the latest research usually means that astronomers get the spectral lines of all measurable elements such as hydrogen, carbon, nitrogen, oxygen and iron through solar spectral analysis, and then compare them with the spectral lines given by the solar atmospheric model. When the two are consistent, the abundance of elements such as hydrogen, carbon, nitrogen, oxygen and iron used in the atmospheric model is considered as the element abundance of the solar photosphere. "However, this method cannot obtain the relative abundance of inert gases such as helium, neon and argon. The abundance of helium on the surface of the sun can only be inferred by helioseismology. " Yang Wuming said.
After the latest measurement results come out, many people are wondering: Why is there such a big difference between the solar metal abundance measured before and after?
In this regard, Yang Wuming explained that the old solar metal abundance was derived from the one-dimensional atmospheric model of local thermal balance combined with the observed spectral lines; The new solar metal abundance is derived from the three-dimensional atmospheric model of non-local thermal balance combined with the observed spectral lines. The old one-dimensional atmospheric model is considered to ignore many physical factors. Some scientists think that the new atmospheric model is closer to the real situation, and it is the improvement of the atmospheric model and the update of the transition probability data of atoms and molecules that cause the difference in the abundance of old and new metal elements.
In the evolution of stars, if other conditions remain unchanged, the decrease of metal abundance will lead to the energy generated by the central nuclear reaction radiating outward more easily. However, the energy tends to radiate outward, which will cause the star to contract more easily and increase the density and temperature of the center of the star. More importantly, the increase of density and temperature will accelerate the hydrogen combustion rate, which will lead to the shortening of the total time of central hydrogen combustion, that is, the main sequence life of the solar model will be shortened. However, if other conditions change, such as the increase of hydrogen abundance or the influence of the sun’s rotation on its evolution, then the aforementioned life reduction does not exist.
So, how to verify which method is more correct in the future?
In Yang Wuming’s view, the answer to this question lies in which metal abundance measurement is more accurate and whether the helioseismology inversion result is reliable. Only by giving the correct abundance of solar elements can we determine how long the life of the sun is. If we can give a new solar model of gold abundance consistent with the helioseismology inversion results, all related problems will be solved.
Life geometry is related to the theory of stellar evolution.
Chen Pengfei, a professor at the School of Astronomy and Space Science, Nanjing University, said that he was inclined to think that the initial life span of the sun was correct, and the life span of the sun would not be reduced by one billion years. "For several reasons, I prefer to think that the original model is correct: first, the measurement results of metal abundance in the solar wind by satellites support 1.8%; Secondly, the density of photosphere on the surface of the sun is high enough, so it is reasonable to adopt the approximation of local heat balance model in the past; Thirdly, the new model takes into account the inhomogeneity of the solar atmosphere, which is indeed an improvement, but it also ignores other factors, such as the influence of magnetic field; Fourth, to take a step back, even if the results of the new model are correct, because the distribution of metal abundance may be uneven, the metal abundance on the surface of the sun may be different from that inside. " Chen Pengfei said.
At the same time, Yang Wuming also agrees that the initial solar life is correct. He said that the life of the sun has not been overestimated by 1 billion years, and that the life of the sun is overestimated because only the reduction of metal abundance is considered. When the influence of hydrogen abundance increase and rotation on the evolution of the sun is considered, the life of the sun will not be reduced.
However, the astrophysicist Martin asp Lund of the Australian National University insists that the 1.3% solar metal abundance is correct. He said that all aspects of astronomy will be affected, and an accurate understanding of the evolution of stars has laid the foundation for almost everything.
So, if astronomers do overestimate the life of the sun by one billion years, what theories need to be revised?
In Yang Wuming’s view, if the life of the sun is really overestimated by 1 billion years, it shows that the theory of stellar evolution established by astronomers before is not complete, so they need to re-examine the theory and model of stellar evolution established before. For example, the standard theory of star evolution ignores the influence of star rotation, but in fact all stars are rotating. We have reached the time when we need to seriously consider the influence of rotation on the evolution of stars. Astronomical research on star clusters and galaxies depends on the theory of stellar evolution to a certain extent. If the theory of stellar evolution is wrong, the previous understanding of star clusters and galaxies needs to be adjusted.
Original title: Lingao Volleyball Championship | Ding ‘an Team won the first victory with 3: 1 lecturing Haikou.
New Hainan Client, Nanhai Net February 18 th News (Reporter Liang Zhenwen) On February 18 th, the "Chinese Dream and Working Beauty"-"Witt Cup" 2024 Hainan (Lingao) Trade Union Elite Volleyball Championship was launched in Binjiang Park, Lingao County. The opening match was played by Ding ‘an team vs Haikou team, and finally Ding ‘an team beat Haikou team 3-1 to get off to a good start.
Ding ‘an team beat Haikou 3-1 to win the first game, and Haikou team served. Reporter Wang Chengxian photo
In the first game, Ding ‘an team took the lead in kicking off. Ding ‘an team entered the state earlier, and gained a 4-1 lead through serving and the opponent’s mistakes. The Haikou team then counterattacked and scored continuously through spiking, and the score was 4:3. Then the two teams fell into a stalemate, and Haikou team took a 10:9 lead through No.2 smash and double block. The scores of the two sides once again entered anxiety, and the coaches of the two teams also suspended the adjustment one after another. In the end, the Ding ‘an team won the first game with a thrilling 22:20.
The coach of Haikou team exchanged tactics with the players after the timeout. Reporter Wang Chengxian photo
In the second game, Haikou scored a block and led 2-0. Ding ‘an team immediately made an adjustment and tied it at 5:5. By serving, Haikou team quickly opened the score, 12:8. Ding’ an team had to call a time-out adjustment and score by stealing the ball through the second pass to stabilize the situation. However, the Haikou players in this game were in a hot state. They scored continuously through spiking and blocking, and they were in a bad state when they joined Ding ‘an team. Haikou team won the second game with a huge advantage of 21:11. The two teams drew a big score of 1:1.
Haikou players struggled to save the opponent’s attack. Reporter Wang Chengxian photo
Ding ‘an team blocked the attack of Haikou players by two people. Reporter Wang Chengxian photo
At the beginning of the third game, Haikou team continued the state of the previous game and led by 5:0. Ding’ an team can only call a time-out to make adjustments. However, because the whole team is not in the state, it still lags behind by 3:9. The Haikou team continued to maintain its state and continued to lead at 12:6 through blocking. Ding’ an team had no choice but to call a time-out adjustment again. By slashing and serving, they scored one after another and clinched the score at 13:15. Depending on the fierce chasing momentum of Ding ‘an team, Haikou team can only call a time-out for adjustment. On the 13th, Ding ‘an scored three points in a row by serving, and Ding ‘an led by one point at 16:15. Haikou team quickly adjusted its state and scored a 20:20 draw through smash. Entering the key points, Haikou team once again suspended the tactics, but the momentum of Ding ‘an team has started, and finally Ding ‘an team won the third game with a reversal of 22:20. Take a temporary lead with a big score of 2:1.
Haikou team launched an attack. Reporter Wang Chengxian photo
At the beginning of the fourth game, Ding ‘an team broke Haikou’s pass by serving and took a 5-1 lead. Continue to lead by 7:1 through smash. Haikou team can only call a 30-second short pause and rearrange tactics. Haikou scored 4:7 by spiking. Seeing that the Haikou team is gaining momentum, the Ding ‘an team is also called to suspend adjustment. Through the smash, the situation was stabilized with a lead of 9:6. Haikou team was full of momentum, scored successively by blocking and smashing, and overtook Ding ‘an team by 10:9. The Ding ‘an team called for a pause for adjustment for the second time, and the two teams tied for the first time at 12:12. Subsequently, at 16:16, 17:17 and 18:18, the scores of the two teams alternately led and tied. In the end, Ding ‘an team won by 21:18, with a total score of 3:1, and got off to a good start. (Liang Zhenwen)
It is reported that the volleyball qualifying tournament of the Paris Olympic Games in China has been decided to be held in Ningbo. It’s good news for China team to participate in the competition in familiar venues. Cai Bin, head coach of China Women’s Volleyball Team, once said that the goal of China Women’s Volleyball Team is to get the Olympic qualification in the first time.
In recent years, Beilun, Ningbo is one of the two major training bases of China women’s volleyball team in China. In the last Olympic cycle, it was in Ningbo that China women’s volleyball team passed the Olympic qualifiers and obtained the Olympic qualification at the first time.
The women’s volleyball qualifying tournament for the Paris Olympic Games will be held in China, Japan and Poland from September 16th to 24th. Twenty-four teams will be divided into three groups, with eight teams in each group playing a single round robin competition. The top two teams will be qualified for the Olympic Games, and six Olympic seats will be produced at this stage. The competition system of men’s volleyball is the same as that of women’s volleyball. The competition will be held in China, Japan and Brazil from September 30th to October 8th.
China women’s volleyball team is in the same group as Serbia, Dominica, Netherlands, Canada, Czech Republic, Mexico and Ukraine, while China men’s volleyball team is in the same group as Poland, Argentina, Netherlands, Canada, Mexico, Belgium and Bulgaria. Eight teams in the group played a single round robin, and the top two teams qualified for the Olympic Games. The Asian Games and the Olympic Qualifying Tournaments are held with a short interval and some overlap (the Asian Games will be held from September 23rd to October 8th), while the distance between Ningbo and Hangzhou is not far, which also gives the head coach more space to arrange his troops.
Cai Bin, head coach of China Women’s Volleyball Team, once said that the qualifying goal of China Women’s Volleyball Team is to get the Olympic qualification in the first time. China men’s volleyball team should also strive to play a good game, improve the world ranking, and strive to advance to the Paris Olympic Games through ranking.
Text: Tao Xingying
Photo: vision china
Source: Xinmin Evening News
Editor: Zhuang Qixin, Yang Ye
Audit: Sun Weijun
Shangguan author: Shanghai Sports
With the progress of society and the change of ideas, more and more people begin to choose blind date to find their other half. In this fast-paced era, zhenai blind date platform has become the first choice for many single young people. For blind date, many people have a common expectation, that is, to find a partner who fits their soul. In this process, the professional interpretation of zhenai matchmaker played a vital role.
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The existence and development of blind date platform in zhenai provides more choices and opportunities for single young people to find suitable partners. Through blind date, they can get to know each other more comprehensively and communicate in an open environment. Such communication and getting along with each other will lay a good foundation for them and lead them to a happy married life.
In a word, the love in tune is inseparable from the deep fit of the soul. In the process of blind date in zhenai, soul fit has become the most important consideration. Through the professional interpretation of zhenai matchmaker and the matching algorithm of blind date platform, single young people can find their soul-compatible partners more accurately. The reliability and credibility of the blind date platform in zhenai have been recognized by the majority of single young people. Let’s embrace the changes of this era, believe in the power of zhenai, find a suitable partner and move towards a happy life.
In the Thai hexagrams in the Book of Changes, there is such a message: "Bao Yi, use Feng He, not a distant legacy." "Bao" means gourd, and "Feng River" means crossing the river. It means that the shaved gourd is tied to the body to cross the river so as not to sink to the bottom. This method of crossing the river by hitting water with certain tools reflects that human beings in primitive times have gradually mastered swimming skills. China’s earliest collection of poems and songs, The Book of Songs, also contains a poem describing swimming: "As long as it is deep, the boat will sail. It’s shallow, and it’s a swim. " Take a raft or ferry to the place with deep water, and dive or float to the place with shallow water. It can be seen that people’s swimming skills reached a certain level more than 2500 years ago. As time goes by. People’s skills in water are getting stronger and stronger, and the relationship between swimming and human society is getting closer and closer, and it has been playing an important role in war, production and entertainment.
Navy Boat Wars and Folk Popularization in the Spring and Autumn Period and Warring States Period
During the Spring and Autumn Period and the Warring States Period, the southern vassal states established naval divisions one after another, and carried out boat warfare, so swimming became an essential part of sailor training. The art of war "Six Rice Raiders" says, "Those who are skilled, therefore, cross the river in deep water; A strong crossbow leads a long army, so it is also a battle over water. The skill of crossing rivers over deep water is called "strange skill". The book Guanzi also records such a historical material: In order to deal with wuyue’s powerful water army, Qi Huangong built a dam on the river to build a large-scale swimming pool, with a depth of 10 meters, and ordered that "those who can swim will be given a thousand dollars". Trained 50,000 foot soldiers who are good at swimming, and defeated the navy of Yue State. Now hidden in the Palace Museum during the Warring States Period, there is a picture of people and fish swimming together at that time, and their swimming posture is harmonious and natural, similar to the current freestyle posture.
While being carried out as a military training project, swimming activities have also gained a certain degree of popularity among the people. In Zhuangzi Dasheng, there is a story that reflects the folk swimmers: the water of Luliang falls from the cliff of Baizhang, and the waves in the river are rolling and foaming, and the fish and turtles can’t swim. Confucius once stood on the waterfront of Luliang and saw a man writhing in the water, thinking that he was going to drown, so he made his disciples go with the waves to save him. Unexpectedly, the man suddenly surfaced a hundred paces away, singing loudly and enjoying himself, and inviting him to swim down the shore was better than taking a stroll. Such superb swimming skills show that swimmers have mastered the tricks of swimming and the characteristics of water.
Swimming Technology in Qin and Han Dynasties
The swimming technique in swimming also appeared very early in ancient China. After Qin Shihuang wiped out the princes, he began a four-way cruise to show off his literary and political skills and consolidate the unified feudal dynasty. According to Historical Records, when he arrived in southern Shandong today, he was told that a bronze tripod of the Zhou Dynasty was sunk in the Swish River here, so he "prayed for fasting and wanted to leave Surabaya, Zhou Ding". He can’t wait to "make thousands of people have no water to ask for, Fu De". This swimming technique was further developed in the future. Hepu County, a coastal county in the Han Dynasty, was rich in pearls. At that time, swimming technology was adopted to collect pearls in the sea. This kind of water production activity has created conditions for the popularization of water sports.
After the Qin and Han Dynasties, water sports became increasingly prosperous, and there were many experts in swimming. "Biography of Zhou Chu in the Book of Jin" describes that the warrior was good at swimming around and dared to fight. Once, he "fought the dumpling in the water, and the dumpling sank or floated, and the number of lines was ten miles, and the place (Zhou Chu) was with it. After three days and three nights, he killed the dumpling and returned." Being able to fight with the dragon in the water for three days and three nights shows that its swimming skills have reached a very high level. Dunhuang Mogao Grottoes, located in the northwest of China, have vivid images reflecting social life in various periods. On the top of the flat base at the back of Cave 257, there is a swimming image of the Northern Wei Dynasty. Four athletes swimming in the water, some of them raised their arms high, as if they were paddling at the same time, like the butterfly stroke now; Some hands are pulled back and forth, which is a bit like freestyle today.
Tide-makers in Song Dynasty
Tide, water sports. It is a large-scale water activity including swimming. In the Song Dynasty, frolicking activities reached a climax. Wu Zimu recorded the spectacular scene of Wu’s frolic in the waves in Old Wulin: "The tide in Zhejiang is a magnificent view in the world." In this tide of "coming from the next day" and "swallowing the day and the day", "Wu Er is good at swimming, all wearing tattoos and holding ten big colorful flags, rushing forward and catching up, haunting the whale wave Wan Ren, changing himself, but the tail of the flag is slightly wet. "The skill and courage of these frolicters are really admirable. Some literati in the Song Dynasty were shocked to see these performances. When recalling this spectacular scene, Xin Qiji, a poet in the Southern Song Dynasty, left such words: "Wu Er is not afraid of the dragon’s anger, and the storm is flat, watching the red flag fly, jumping straight on the fish, jumping on the waves and dancing." The superb skills of swimmers are on the page.
Swimming competition started in Han and Wei Dynasties.
The swimming competition in China began in the Han and Wei Dynasties, when there was already a folk custom of holding a swimming competition on the Dragon Boat Festival. Every time this kind of competition is held, it is very grand and has a large number of participants. During the Tang and Song Dynasties, a large-scale swimming competition was held on the Qiantang River during the Dragon Boat Festival every year, and in line with the folk swimming activities, the royal family also held swimming competitions every year. "History of Song Dynasty. Rites" contains: In March of the third year of Chunhua (992), it was the early spring, and the river was very cold. Song Taizong Zhao Ling inspected the water army in Jinmingchi. He ordered people to throw the silver ou between the blue waves and let the soldiers swim for it. Of course, it won’t be a person to get the silver ou. This kind of swimming with the nature of competition is obviously to encourage the soldiers to practice their water skills.
Tide-making skills in Ming and Qing Dynasties
The folk swimming activities in Ming and Qing Dynasties are still represented by "frolicking in the waves" in Qiantang River every August. Whenever the tide is high, local people will carry out various swimming activities, and there are more and more patterns. Huang Zunsu’s "Ode to Watching Tides in Zhejiang" in the Ming Dynasty describes the thrilling scene of hundreds of frolic athletes performing various strange skills in the wild waves in red light clothes. Records of the west lake said that during the frolic activities, more than 100 swimmers held colorful flags, swam to Haimen to meet the huge tide, and then churned in the rolling tide. There are also people who perform "rolling on the wood", "water puppet" and "water acrobatics" on the water, which is a comprehensive skill of swimming and acrobatics. In addition to the watery areas in the south of the Yangtze River, it is the north, and swimming activities are also carried out to a certain extent at this time. At the end of the Qing Dynasty, Guan Kanglin, a native of Nanhai, wrote a poem about Beijingers’ spring swimming in Du Men Zhuzhi Ci, which read: "Swimming has become a new stone pool, and Cao Cao competes to build a red flag. After undressing, the spring waves are cold, and people are still playing with water. " This is about a folk swimming competition, but for this wanderer from the south, he felt itchy when he saw a northerner swimming, and he wanted to have a try. Finally, he gave up because he was afraid of the cold, so he had to watch others swim in the water. In Tashilhunpo Monastery in Shigatse, Tibet, a swimming mural dating back more than 500 years ago is preserved, and its swimmer’s posture of paddling and backstroke is vivid. It seems that even on the Qinghai-Tibet Plateau, which is known as the "roof of the world", people have mastered quite superb swimming skills.
Swimming as a military training program
With the development of folk swimming activities, swimming as a military training project has also been paid attention to. For example, Qi Jiguang, a famous anti-Japanese fighter in Ming Dynasty, attached great importance to water warfare, and trained the navy in water sports such as swimming to meet the invading Japanese pirates. Mao Yuanyi’s "Wu Bei Zhi" recorded that the water army of Ming Dynasty was selected from the "Shamin" who was good at swimming, because this "Shamin" grew up on the seashore, was familiar with water, and walked on the ground in the waves. In the battle of coastal soldiers and civilians against pirates in the late Qing Dynasty, the importance of swimming was even more obvious. Gu Han’s poem "Song of Yujiazhuang" tells that the fishermen in Yujiazhuang, Shengxian County, Zhejiang Province, with superb water skills, carried grass and other things to the bottom of the enemy’s ship and wound the equipment, thus defeating the enemy.
The ancient swimming activities in China were like this. In the combination of folk and military training, they promoted each other and developed together. With its long history and rich contents, it has become a traditional sport with national characteristics.
Editor: Chen Chang ‘e