by 1900, people think that the solar system belongs to the milky way is the whole universe.as for the size of the milky way, the boldest estimate was a width of about 20,000 light years(light years, that is, the distance traveled by the year, about 9460.5 billion kilometers), which contained about 20 to 30 million like the sun the stars.
in 1920, the astronomer harlow shapley et al., according to the new method of measuring the distance of the star,
calculate the true width of the milky way is 100,000 light years, which contains a total of 2000-3000 billion stars.compared with the view of 20 years ago, the galaxy"expanded"100 times, but also concluded that the expansion of the galaxy, not all the universe.at the same time, astronomers have discovered that the universe is integrated by many galaxies like galaxies, each consisting of billions of billions of dollars.and proved that the universe is dynamic, clusters of galaxies exist apart from each other, the distance between them is growing, as if the universe is also expanding.in 1929, the american astronomer edwin p.hubble and so on.in 1929, the american astronomer, edwin p hubble, and so on.
people have designed a variety of ways to determine the distance of galaxies, to prove that even if we are closer to the galaxies(such as fairy constellation), we also have 2.3 million light years away.in the 1960s, it was found that some of the stars that were once considered to be luster in our own galaxies were in fact far from our galaxies and were called"quasars".these"quasars", the nearest from us there are 1 billion light years, far more than 12 billion light years.
according to the rapid expansion of the universe after the birth of the universe model, you can calculate the universe the age of 13 billion years.that is to say, from the earth to the universe"the end"of the distance, theoretically should be 13 billion light years.
as to how big the universe is, its"end"where it is, it will always be a mystery.
the universe's conjecture
how is the universe produced?
of? this is the biggest mystery of today.at present, most scientists accept the"big bang cosmology".this doctrine that the universe originated in a very high temperature, minimal volume of the original fireball.in the 150~ 20 billion years ago, because we do not know the physical reasons, the fireball had a big bang.with the expansion of space, the temperature decreases, the density of the material is gradually reduced, the original existence of protons, neutrons and other basic particles combined into deuterium, helium, lithium and other elements, and later gradually formed galaxies, clusters of galaxies, and gradually formed stars, planets, but also in some celestial bodies also appeared in the phenomenon of life, and finally the birth of mankind, the initial formation of the universe.
the big bang theory is constantly being confirmed.on april 23, 1991, george smith, a professor of astronomy at the university of california, announced at the american institute of physics that the scientific team he led had discovered the material cloud at the beginning of the universe and supported the big bang theory.
these discoveries have aroused great concern from the world's scientific community,"this is the most important discovery of this century."
the great explosive theory, says paul hawking, the most prominent theoretical physicist after einstein, said on april 24, can explain more observations.for example, astronomers have observed that distant objects are always away from the earth, which proves that the universe is still expanding; the age of the celestial bodies is less than 20 billion years, which is consistent with the theory of the big bang after the formation of a variety of objects inference.in addition, the big bang theory has succeeded in predicting the presence of cosmic background radiation.the big bang theory predicts that after the big bang, the structure of the universe should be a cloud before the formation of galaxies.the discovery of this huge cloud confirms the prophecy of the big bang theory, and by observing the cloud, scientists can further speculate on the early stages of the universe.
the discovery of this giant cloud also confirms the a prediction that 90% of the mass of the universe exists in the"dark matter".in the past, astronomers have observed that the total mass of the universe is much smaller than the total mass of the universe calculated theoretically.these"vanishing"substances are called"dark matter"."dark matter"directly affects the future of the universe, if the total mass of the universe is less than a certain value, then it will be like this has been expanding; if its total mass is greater than this value, then the celestial force between the universe will make the universe stop the expansion, and in this great gravity began to shrink under the formation of the universe"big collapse"until the state before the big bang.
the movement of the universe has a regularity and harmony seems to have become a eternal creed.from the time of the ancient greek period, the famous pythagoras school put forward the"beauty is harmony and proportion", and then pointed out that the universe of human life is because of this harmony was evolved to today and orderly.it is also because of this harmony, the celestial body should be spherical, its movement should also be circular motion.in the 16th century, copernicus, through its own observations, rejected the traditional ones.
"heart to say", put forward the"heliocentric".he believes that the sun as the center of this universe model is consistent with the laws of celestial bodies, but also reflects a"wonderful harmony."later, the german astronomer kepler also highly respected the aesthetic principles of pythagoras, the celestial movement with the music scale linked.newton made a more in-depth discussion of the movement of celestial bodies, and he proposed the law of gravitation, not only to make a more scientific explanation of the changes in the movement, but also to guide astronomers to discover neptune.newton's law of gravity shows that the order of the universe is so harmonious.
this"first harmony"also affects the study of modern astronomy.the notion of the"big bang", which reflects the expansion of the universe, embodies the principle of"harmony", which is based on hubble's observation of galaxies redshift and predicts the existence of microwave radiation in the cosmic background.these are the cosmic harmony picture in the large-scale space on the reproduction.
modern physicist einstein pointed out that the universe of this first harmony can give people a sense of beauty and pleasure, is all human literature and artistic creation, perseverance and patience to produce the source.
for a long time, the harmony of the universe has been widely accepted, but in recent years has been a challenge.some people in the massachusetts institute of technology scientist sass, the astronomer weizdem, argue that the entire solar system is simply unpredictable,
perhaps four million years later, newton's theory proved to be wrong.they argue that there is a phenomenon in the universe that predicts, according to a simple law, that many accidental factors can lead to very complex and irregular phenomena, which is chaotic.
so, is the universe dominated by harmony or chaos? this is really an unexplained mystery.1854, the german scientist helmholtz proposed the universe of death, he pointed out that the universe can only make all the energy into heat, and/and finally in a state of uniformity, and thus the universe into an eternal static state.this hypothesis is also known as thermal death hypothesis or thermodynamic hypothesis.
the thermal death hypothesis has caused panic in the world, because it is dead of the universe is equal to the world's coming, in order to eliminate this hypothesis, many scientists have tried this, the german physicist klausius and the austrian physicist bolzman had argued, the latter that the universe is not only in one direction, but also in the opposite direction.engels also does not agree with the idea of hot dead fake, he believes that this principle with the conservation of energy contradictory.
since the thermal death hypothesis contradicts the infinite universe, the cosmologists who advocate the big bang theory are resolved from the perspective of the expansion of the universe.russian scientist friedman has done a sophisticated calculation, the results show that the universe may be periodically contraction and expansion, may also be unlimited expansion.later, the american astronomer hubble used the 1.5-meter telescope and the 2.5-meter telescope on mount wilson in california, and found that the universe was expanding.according to this view, the universe is divided into particles and radiation(such as light, infrared, ultraviolet x-ray), due to the thermal expansion of the universe, the particles are heat balance, radiation is heat balance, but the heat between the two is not balanced must have a certain time, due to the gravitational effect, so they do not have enough time to reach the heat balance.however, some scientists have questioned the thermal expansion of the universe, and the interpretation of certain specific physical properties to the beginning of the universe is unsatisfactory.people hope that the universe will not have the day of death, hope that life and civilized world continues, but has not been found to solve the problem of thermal death hypothesis.
the most mysterious mystery in the universe
the so-called"black", that it does not launch and reflect any light to the outside, so people can not see it, it is"black"; the so-called"hole"is that any thing into its borders will never expect to go out, so it like a real"bottomless pit".why does the black hole have such a feature? this is because it has a very strong gravitational field, so that anything, including light, can not escape from it.not only that, the black hole strong gravitational field is enough to destroy all its internal objects, so the black hole does not have any type of material structure, which is the famous"black hole impermanence theorem."the black hole has a strange, unimaginable nature.
the density of it is so amazing that if the sun turns into a black hole, its radius will be from the current 700,000 km"compressed"to 3 km or so, that is reduced to twenty-three thousandth; if our planet into a black hole, then its radius from the current more than 6000 km"compressed"to only a few millimeters, the equivalent of a small green beans.after the astronomers study, there are three views on the source of the black hole:first, the stars in their later years all the depletion of nuclear fuel, the stars in its own gravitational force began to shrink the depression, if the quality of the material is greater than the sun quality of 3 times, then shrinkage of the product is a black hole; second, the central part of the galaxy or globular clusters are very dense stars, stars are prone to large-scale collision between, resulting in large mass of celestial bodies collapsed, they can form the quality of more than 100 million times the sun of the black hole; third, according to the big bang model of the universe inferred that the great power of the big bang will squeeze some of the material is extremely close, so the formation of the"native black hole."astronomers also list the facts of many orbital orbit distortions to confirm the presence of black holes.however, although astronomers have identified the existence of black holes, but no one to find a black hole.therefore, the existence of black holes, is still a mystery.