BIGBANG is just a theory, an idea based on astronomical observation and research. About 5 billion years ago, all the substances in the universe were highly concentrated at one point and had extremely high temperatures, which led to a huge explosion. After the big bang, matter began to expand outward, forming the universe we see today. The whole process of the Big Bang is complicated, and now we can only describe the history of the development of the ancient universe on the basis of theoretical research. In this/kloc-0.5 billion year, galaxy clusters, galaxies, our galaxies, stars, solar systems, planets, satellites and so on were born one after another. Now all the celestial bodies and cosmic substances we see and can't see have formed today's cosmic form, and human beings were born in this cosmic evolution. How can people speculate that there may be a big explosion? It depends on astronomical observation and research. Our sun is just one of the120 billion stars in the Milky Way. Such as our Milky Way, extrasolar galaxies and Qian Qian. From the observation, it is found that those distant galaxies are leaving us. The farther away galaxies are, the faster they fly, thus forming an expanding universe. In this regard, people began to reflect, if we look at these galaxies that are far away from each other in all directions, they may have been emitted from the same source from the beginning. Was there an unimaginable big bang at the beginning of the universe? Later, we observed the microwave background radiation that filled the universe, that is to say, the aftermath generated by BIGBANG about 654.38+0.5 billion years ago was weak but did exist. This discovery is a strong support for BIGBANG. Big Bang Viewpoint: 1932, Lemaistre first put forward the modern big bang theory: the whole universe first gathered in a "primitive atom", and then the big bang happened, and the fragments scattered in all directions, forming our universe. Gamov, an American Russian astrophysicist, first integrated general relativity into the theory of the universe and put forward a cosmological model of the Big Bang: the universe started from high-temperature and high-density primitive matter, and its initial temperature exceeded several billion degrees. As the temperature continues to drop, the universe begins to expand. 1965, penzias and Wilson discovered the cosmic background radiation. Later, they confirmed that the cosmic background radiation was a relic left by the Big Bang, which provided an important basis for the Big Bang theory. They also won the 1978 Nobel Prize in Physics. Hawking embodies the wisdom and perseverance of science in the 20th century. He clearly explained the evolution of the universe since 10-43 seconds after the origin of the universe. The origin of the universe: at first it was a singularity smaller than an atom, and later it was the Big Bang. Some elementary particles were formed by the energy of the Big Bang, and these particles gradually formed various substances in the universe under the action of energy. At this point, the Big Bang model has become the most convincing theory of the universe. However, so far, the Big Bang theory still lacks the support of a large number of experiments, and we still don't know the picture before and after the universe began to explode. Big Bang Theory: Big Bang Theory is the most influential theory about the formation of the universe, which is called Big Bang in English and also called Big Bang Cosmology. The Big Bang Theory was born in the 1920s, supplemented and developed in the 1940s, but it has been unknown. It was not until 1950s that people began to pay extensive attention to this theory. The main idea of the Big Bang theory is that our universe once had an evolutionary history from hot to cold. During this period, the cosmic system is not static, but constantly expanding, which makes the density of matter evolve from dense to sparse. This process from hot to cold, from dense to thin, is like a huge explosion. According to BIGBANG's cosmology, the whole process of BIGBANG was in the early universe, and the temperature was extremely high, above 1000 billion degrees. The density of matter is also quite large, and the whole universe system is in equilibrium. There are only some elementary particles in the universe, such as neutrons, protons, electrons, photons and neutrinos. But because the whole system is expanding, the temperature drops rapidly. When the temperature drops to about1000 billion degrees, neutrons begin to lose the condition of free existence, and they either decay or combine with protons to form heavy hydrogen, helium and other elements. It was from this period that chemical elements began to form. When the temperature further drops to 6.5438+0 million degrees, the early process of forming chemical elements ends (see the theory of element synthesis). The substances in the universe are mainly protons, electrons, photons and some lighter nuclei. When the temperature drops to several thousand degrees, the radiation decreases, and the universe is mainly gaseous substances, which gradually condense into gas clouds, and then further form various star systems, becoming the universe we see today. The Big Bang model can uniformly explain the following observation facts: a) The theory holds that all stars were born after the temperature dropped, so the age of any celestial body should be shorter than the period when the temperature dropped to today, that is, less than 20 billion years. The measurement of the ages of various celestial bodies proves this. B) It is observed that the celestial bodies outside the river have a systematic red shift of spectral lines, and the red shift is roughly proportional to the distance. If it is explained by Doppler effect, then the red shift is a reflection of the expansion of the universe. C) Helium is quite abundant in various celestial bodies, most of which are 30%. The mechanism of stellar nuclear reaction is not enough to explain why there is so much helium. According to the big bang theory, the early temperature was very high and the efficiency of producing helium was also very high, which can explain this fact. D) According to the expansion speed of the universe and helium abundance, temperature of the universe in each historical period can be calculated concretely. According to the Big Bang theory, the universe was born at a tiny point 654.38+0.5 billion years ago. From this tiny point, space-time, mass and energy were born, which made small particles of matter gather into mass matter and eventually formed galaxies, stars and planets. Before the Big Bang, there was no matter, no energy and even no life in the universe. However, the big bang theory can't answer what the universe was like before the big bang, or what was the cause of the big bang? According to the big bang theory, the universe has no beginning. It is just a cyclical process, from the Big Bang to the black hole, which is the process of the creation and destruction of the universe and its rebirth. This is just an idea, not a perfect theory. Although the big bang theory is not mature, it is still the mainstream theory of the formation of the universe. The point is that there is some evidence to support the big bang theory. The more traditional evidence is as follows: a) redshift From any direction of the earth, distant galaxies are leaving us, so it can be concluded that the universe is expanding, and the farther away galaxies are, the faster they expand. B) Hubble's law Hubble's law is about the relationship between the speed and distance between galaxies. It still explains the motion and expansion of the universe. V = h× d, where v (km/s) is the departure speed; H(Km/sec/Mpc) is Hubble constant, which is 50; D(Mpc) is the distance between galaxies. 1MPC = 3.26 million light years. C) The model predicts that the abundance of hydrogen and helium is 25% for hydrogen and 75% for helium, which has been confirmed by experiments. D) Abundance of trace elements For these trace elements, the estimated abundance in the model is the same as the measured abundance. E)3K cosmic background radiation According to the Big Bang theory, the universe cooled due to expansion, and there should still be radiation embers produced at that time in today's universe. At 1965, the background radiation of 3K was measured. F) The trace inhomogeneity of background radiation proves that the initial state of the universe is uneven, which is also the reason why the present universe and the present galaxies and clusters of galaxies are produced. G) New Evidence of the Big Bang Theory In the February 2000 issue of the British magazine Nature, scientists said that they had found new evidence that could be used to confirm the Big Bang theory. For a long time, there has been a theory that the universe was originally a point with great mass, small volume and extremely high temperature, and then this point exploded, and with the expansion of its volume, the temperature kept decreasing. Today, there are still cosmic rays called "cosmic background radiation" in the universe at the beginning of BIGBANG. After analyzing the light absorbed from quasars by distant gas clouds in the universe billions of years ago, scientists found that its temperature was indeed higher than that of the universe today. They found that the background temperature was about 263 degrees below zero. 89 degrees Celsius, which is higher than the measured temperature of -273.33 degrees Celsius in temperature of the universe. Although the above evidence exists, there is still not enough convincing evidence whether the universe originated from the Big Bang theory. The Big Bang theory is a major school of modern cosmology, which can satisfactorily explain some basic problems of cosmology. Although The Big Bang Theory was put forward in the 1940s, it began to sprout in the 1920s. In the 1920s, many astronomers observed that the spectral lines of many extragalactic galaxies had wavelength changes compared with the spectral lines of the same element on the earth, that is, the phenomenon of red shift. By 1929, American astronomer Hubble summed up the law that the stars whose spectral lines are red-shifted are directly proportional to the distance from the galaxy to the earth. He pointed out in theory that if the red shift of spectral lines is the result of Doppler effect, it means that galaxies outside the river are moving away from us and retreating far away, and the farther away the galaxies are, the faster they are. This is the image of the expansion of the universe. In the 1940s, American astrophysicist Gamov and others formally put forward the Big Bang theory. According to this theory, the universe was in a state of extreme high temperature and high density in the distant past, which was vividly called "primitive fireball". Later, the fireball exploded, the universe began to expand, the density of matter gradually became thinner, and the temperature gradually decreased until today's state. This theory can naturally explain the red shift of spectral lines of celestial bodies outside the river, and can also satisfactorily explain many astrophysical problems. 1964, Americans penzias and Wilson found new strong evidence of the Big Bang theory. As a developing theory, this theory has been recognized by most scientists, but there are still some unexplained problems that need to be further improved. Evaluate the answer