Understanding of the universe - the universe is expanding.

<P> Second, the universe is expanding 1. .Recalling the history of the universe has no origin and end, it is eternal, or evolution? .This is in addition to the structure of the universe than another fundamental problem. .All civilizations have their own views on the origin of the universe, an epoch-making in China Pangu legend, God created the world in the West myth. .As for the situation after creation, the ancient Chinese literature, there were ill touch the mountain of angry workers, severing Tianzhu, sky falls down, the story of the Sky Goddess. .In a very long period of time, due to the feudal society, the level of political darkness and limitations of observations, so that some spark of truth shines with wisdom bud failed to develop a scientific theory tree. .Until the 17th century, the rapid development of natural science, especially the Kant solar nebula theory of the origin of Darwin's evolution theory on the origin of species such as the proposed, constantly hitting the "days of the same, also the same road," the .Natural rigid view of the position. .Until the 20th century, many observations of scientific evidence-based theory of cosmic origin and evolution of a formal declaration before the birth. .</ P> <P> 2. .The birth of modern cosmology model of the modern universe began in Einstein. .Einstein's general theory of relativity predicts that a certain quality of the objects, will affect the space around them leaving "bending." .Curved space will force them through the deflection of light, such as the sun will cause the edge of the distant stars through their place of light deflection of 1.75 arc seconds. .Typically, the sun's light is too strong it can not be observed leaving the fact. .1919 total eclipse took place, a British expedition finally observed deflection of light near the sun to get the deflection data is predicted by Einstein's "1.75 arc seconds." .</ P> <P> Einstein's general theory of relativity, but that does not like the people time and space (Newtonian theory) has always maintained that it: space just an object in which the movement itself has not affected the container; .Time is like a river into the sea, the natural flow. .Space depends on its shape is more like a ball on the flexibility contained in the film, free particle and the deformation of optical film along the curved geodesic motion, as if they were in a small ball under the action of gravity as deviation from the straight line; time .is associated with the state of motion, but also through the state of motion and space (reference frame) had contact. .This on time, space and a new theory of gravity, not only correctly predicted the edge of the stars passing the sun will occur deflection of 1.75 arc seconds, and satisfactorily explained Newton's gravitational theory can not explain the perihelion of Mercury each century forward .43 arc seconds of the "Mercury precession," and, therefore, people gradually recognized, for the staging of this magnificent modern cosmology a solid theatrical setting up the stage. .</ P> <P> 1917, Einstein first applied his theory of general relativity cosmological research, get a "limited unbounded static universe" model. .According to general relativity, the geometric nature of the universe depends on the mass distribution, corresponding to the gravitational field to make it curved, "Riemannian geometry of space." .The so-called "limited free world" is that the universe is a closed curved body, its volume is limited and material distribution; and "static" is to the universe in terms of overall space, not to say that all parts of the universe completely stationary .. .Though later (1922) found that the universe was not stable to give up, but that is a pioneering attempt, opened the curtain of modern cosmology. .3. .The universe is expanding in 1922, the Soviet mathematician Friedman in the framework of general relativity, Einstein's Universe has been a set of dynamic equation solution, either from the theoretical argument expansion of the universe, or contraction, will never be maintained .stationary state. .Trends in the evolution of the universe depends on the average density of cosmic matter and the critical density ρc ρ0 ratio: </ P> <P> the first two cases, the universe will expand forever; the latter case, the universe will shrink swollen ─ ─ .shock that "pulse." .(Now known as the critical density ρc = 10-29 g / cm 3, the observed non-"dark matter" of the average density is ρ0 = 2'10-31 g / cm 3) </ P> <P> us .There is no way to observe the universe, galaxies, the basic members of the movement ─ ─ it? .These galaxies are moving away from us can be, or is it closer to us? .Like you could find its own stars (the star on the celestial sphere between the relative position change), through the comparison of astronomical photos taken in different times to discover what their own galaxy? .That, at least in the current technical conditions is impossible, because the extragalactic too far away from us. .However, the determination of physics provides us with a powerful light-emitting object velocity ─ ─ Doppler effect means that the galaxies by measuring the red shift of spectral lines, purple shift to guess their speed: line or wavelength .relative movement of the volume and relative velocity is proportional to. .</ P> <P> 4. Doppler effect, red shift and blue shifted spectrum in the last century, astronomers have used the Doppler effect to measure the speed of the stars away from us. .When the train off to our fast, we will hear it more and more sharp whistles (audio goes high or wavelength is compressed); the contrary, when you are away from the train when the whistle is that it becomes boring .(audio become elongated low or wavelength), this is the physics of the Doppler effect, which is by the Austrian physicist Christian Doppler (Chris-tian DoPPler ,1803-1853 years) in 1842 found ., while the French physicist Feizi Ao (A. Fizeau) will be extended to the light Doppler effect. .As with sound waves, when the light source away from our movement, its optical frequency becomes low, it can be observed spectral lines (such as hydrogen atomic line) to the red end of the shift, and the greater the speed of light away from us it's red .The larger shift; and light coming to us, the optical frequency becomes higher, spectral lines shift to the violet side. .Both in the case in astronomical physics are called "red shift" and "violet shift." .Today, we use the redshift is found and the large number of extragalactic star away from us ─ ─ universe is expanding. .</ P> <P> there is a story made for the Doppler effect, an interesting exposition. .Driving through a red light for a driver to be brought to court. .He is very smart, explained that because the cars run very fast, his eyes became red in the green. .The judge also learned the physics well, worked out, to make the red light turned green as the Doppler effect, the driver must take car to 100,000 km / sec. .So the judge smiled and said to the driver: "I accept your argument, you are speeding!" </ P> <P> Doppler effect is also afraid of the police to make drivers speed monitoring radar, which in astronomy .There are also many useful applications. .Astronomers very sensitive hearing a little bit like the blind, such a person to hear the train whistle sound can be saved to determine the speed and direction of car travel. .Astronomers also use spectrographs by "listening" star's light and measure their movement, this method can not see the companion in the case of binary stars reveal particularly useful exercise. .</ P> <P> 5. Expansion of the universe with Hubble's law by the "Doppler effect", the galaxy redshift v spectral lines corresponding to the velocity of recession of stars, recession velocity, also known as the "red shift speed." .In 1929, discovered and confirmed the existence of the American astronomer Hubble external galaxy (Edwin.Powell.Hubble, 1889 ~ 1953), who further found that "galaxy redshift v spectral lines with their distance from us there is a simple r .The proportional relationship ", this simple relationship can be expressed the following formula: </ P> <P align=center> (Hubble's law relationship or) </ P> <P> relationship of H is called" Hubble constant. " .Just know that the red shift of H values and the amount of stars, you can easily figure out any objects, galaxies in our distance. .Therefore, the "red shift speed" to become the basis for the amount of days. .If we know the scale of the universe, and then assume that our universe is expanding, and the edge of the universe far away from the limitations of our speed is the speed of light c, then we can easily calculate where the constant H is the reciprocal of the age of the universe: </ .P> <P align=center> </ P> <P> based on current observation and calculation, the scale of the universe about 20 billion light-years; about 1.451010-2.051010 age of the universe, that is 140-200 million years, this .According to stellar evolution theory of value and projected life of the oldest stars fit; the Hubble constant H is about 67 ± 15 km / sec MB sec. .</ P> <P> 6. Expansion model in 1927, the Belgian astronomer Lemaitre (Georges Lemaitre, 1894 ~ 1966) in the Friedman "solution" based on the redshift of observed extragalactic .interpreted as large-scale expansion of space results over time, the establishment of the "expanding universe model." .</ P> <P> 1929, the Hubble carefully studied a number of galaxies in the spectrum, found that except for a few exceptions, the vast majority of galaxies have shown a red shift of the spectrum, and galaxy redshift of roughly the same distance as .proportional. .If the redshift interpreted as a Doppler effect, it means that all the galaxies away from us in their recession velocity is proportional to the distance with us. .This is talked about in front of the "Hubble relations or law" (see the first section of chapter.) .If you follow the idea of Copernicus that the universe we are not in a special center of galaxies that Hubble's law is all set up for any, then a direct corollary is: all the galaxies in the universe are .away from each other, that our universe is in a general expansion in! .</ P> <P> Hubble discovered the universe for the model of Friedman's observations provide a direct basis, has shaken the traditional concept of a static universe as a whole, for further study of the origin and evolution of the universe clears the way, is the .century, one of the most important achievements of astronomy. .</ P>.