How to understand that the universe has several dimensions more than the earth? For example, a small ball rolled along the ground and fell into a small hole. In our opinion, the ball exists and is still in the hole, because we humans are "three-dimensional"; For an animal, it will be concluded that the ball no longer exists! It disappeared. Why did you come to such a conclusion? Because it lives in a "two-dimensional" world, it is impossible to clearly understand "three-dimensional" events. By the same token, we human beings live in a "three-dimensional" world, and it is difficult to understand the universe with several dimensions more than ours. This is why the question "What is the universe like" cannot be explained clearly.
1, unified universe
People always think that the earth is the center of the universe. Copernicus subverted this view. He thinks the sun is the center of the universe. Planets such as the earth revolve around the sun, and stars are embedded in the outermost layer of the celestial sphere. Bruno further believes that the universe has no center and the stars are distant suns.
Ptolemy's geocentric theory and Copernicus's Heliocentrism both believe that the universe is finite. The church supports the argument that the universe is limited. However, Bruno dared to say that the universe is infinite, which led to a long-term debate about whether the universe is finite or infinite. The controversy did not stop because the church burned Bruno. Those who advocate the finite universe say, "How can the universe be infinite?" This question is really hard to say clearly. People who advocate the infinity of the universe ask, "How can the universe be finite?" This question is not easy to answer either.
With the development of astronomical observation technology, people see that, as Bruno said, stars are distant suns. People further realize that the Milky Way is a huge galaxy composed of countless solar systems. Our sun system is at the edge of the Milky Way, and it rotates around the center of the Milky Way at a speed of about 250 kilometers per second, and it takes about 250 million years to circle the center of the Milky Way. The diameter of the solar system is about 1 light-year at most, while the diameter of the milky way is as high as 1 100 million light-years. The Milky Way is composed of more than 1000 billion stars, and the position of the solar system in the Milky Way is really like a grain of sand in Beijing. Later, it was found that our Milky Way and other galaxies formed a larger galaxy cluster with a diameter of about 107 light-years (10 billion light-years). At present, the telescope observation distance has reached 1000 billion light years, and there are countless galaxy clusters in the visible range. These clusters no longer form larger clusters, but are evenly and isotropically distributed. That is to say, at the seventh light-year scale of 10, matter is distributed in clusters. Satellites revolve around planets, and planets and comets revolve around stars to form the solar system. These solar systems consist of one, two, three or more suns and their planets respectively. Those with two suns are called binary systems, and those with more than three suns are called galaxy clusters. Hundreds of billions of solar systems gather together to form the Milky Way, and the stars (solar systems) that make up the Milky Way all revolve around the same center of gravity-the center of the Milky Way. Countless galaxies form a galaxy cluster, and the galaxies in the cluster also rotate around their same center of gravity. However, there is no cluster structure between clusters. Each cluster of galaxies is evenly distributed and moves irregularly. From all directions of our earth, the situation is similar. Roughly speaking, galaxies are a bit like gas molecules in a container, evenly distributed and moving irregularly. That is to say, above the scale of 10 to 8 light years (1 100 million light years), the distribution of matter in the universe is no longer clustered, but evenly distributed. Because the propagation of light takes time, the galaxy we see 100 million light-years away is actually what that galaxy looked like 100 million years ago. So we can see not only distant galaxies in space, but also their past with telescopes. From a telescope, no matter how far away the galaxy clusters are, they are uniformly and isotropically distributed.
Therefore, we can think that the uniform state of matter distribution on the cosmic scale (more than 5 light years from 10) not only exists now, but also exists.
Therefore, astrophysicists put forward a law, the so-called cosmological principle. This principle says that on the cosmic scale, three-dimensional space is homogeneous and isotropic at any time. Now it seems that the principle of cosmology is correct. All galaxies are similar and have a similar evolution process. Therefore, the distant galaxies we see through telescopes are not only images of their past, but also images of our galaxy. Telescopes are not only looking at space, but also at time and our history.
2. The finite and infinite universe
After Einstein published the general theory of relativity, he paid attention to astrophysics and thought that gravity was much weaker than electromagnetic force, so it could not have an important impact on the study of molecules, atoms and nuclei. He believes that the universe is a field where general relativity is of great use.
Einstein published his general theory of relativity in 19 15, and put forward a model of the universe based on the general theory of relativity in 19 17. This is a completely unexpected model. In this model, the three-dimensional space of the universe is infinite and does not change with time. In the past, people thought that finite was the edge and infinite was infinite. Einstein distinguished the concepts of finite and bounded.
Rectangular desktop has a certain length, width and area, so its size is limited. At the same time, it has four obvious sides, so it has sides. If a small beetle crawls on it, no matter which direction it crawls, it will soon reach the edge of the desktop. So the desktop is a limited two-dimensional space with edges. If the desktop extends infinitely in all directions and becomes a plane in Euclidean geometry, then this Euclidean plane is an infinite two-dimensional space.
Let's look at the surface of basketball. If the radius of basketball is r, then the area of the sphere is the square of 4πr, and the size is limited. However, this two-dimensional sphere is boundless. If a small beetle crawls on it, it will never end. Therefore, the basketball surface is a limited and infinite two-dimensional space.
According to the principle of cosmology, on the cosmic scale, three-dimensional space is homogeneous and isotropic. Einstein believed that such a three-dimensional space must be a space with constant curvature, that is, every point in the space should have the same degree of curvature, that is, it should have the same curvature. Because of the existence of matter, four-dimensional space-time should be curved. Three-dimensional space should also be curved rather than flat. Einstein thought that such a universe is likely to be a three-dimensional hypersphere. Three-dimensional hypersphere is not an ordinary sphere, but a generalization of two-dimensional sphere. The usual sphere is finite, with sides, the volume is 4/3πr cubic, and the sides are two-dimensional spheres. The three-dimensional hypersphere is infinite, and the three-dimensional creatures living in it (for example, we humans are three-dimensional creatures with length, width and height) can't touch the edge no matter which direction we go. If it keeps going north, it will eventually come back from the south.
Cosmological principles also believe that the uniformity and isotropy of three-dimensional space are maintained at all times. Einstein thinks that the simplest order is the static universe, that is, the universe that does not change with time. Such a universe, as long as it is homogeneous and isotropic at a certain moment, will always remain homogeneous and isotropic.
Einstein tried to solve the field equation of general relativity under the assumption that three-dimensional space is homogeneous and isotropic and does not change with time. The field equation is very complex, and it needs to know the initial conditions (the initial situation of the universe) and boundary conditions (the situation of the edge of the universe) to solve it. It was difficult to solve such an equation, but Einstein was very clever. He imagined that the universe is finite and infinite, and naturally there is no need for boundary conditions without edges. He also imagined that the universe was static, and the present was the same as the past, so the initial conditions were unnecessary. Coupled with the limitation of symmetry (requiring three-dimensional space to be uniform and isotropic), the field equation becomes much easier to solve. But I still can't get the result. After repeated thinking, Einstein finally understood the reason why he couldn't find the solution: the general theory of relativity can be regarded as a generalization of the law of universal gravitation, which only contains the "gravitational effect" and does not contain the "repulsive effect". To maintain a time-invariant universe, there must be a balance between repulsion effect and attraction effect. In other words, it is impossible to draw a "static" universe from the field equation of general relativity. If we want to get a static universe, we must modify the field equation. So he added a "exclusion term" to the equation, called the cosmological term. In this way, Einstein finally developed a static, uniform, isotropic and finite model of the universe. At that time, everyone was very excited. Science finally told us that the universe does not change with time, and it is finite and infinite. The debate about whether the universe is finite or infinite seems to have come to an end.
3. An expanding or pulsating universe
A few years later, F. Lidman, a little-known mathematician in the former Soviet Union, applied the field equation without the cosmological term and got an expanding or pulsating cosmological model. Lidman universe is homogeneous and isotropic in three-dimensional space, but it is not static. This model of the universe changes with time and is divided into three situations. In the first case, the curvature of three-dimensional space is negative; In the second case, the curvature of three-dimensional space is zero, that is, three-dimensional space is straight; In the third case, the curvature of the three-dimensional space is positive. In the first two cases, the universe is expanding; In the third case, the universe first expands, reaches a maximum value and then begins to contract, then expands and then contracts ... so the third universe is pulsating. Lidman's Cosmos was first published in a little-known magazine. Later, some mathematicians and physicists in western Europe got a similar model of the universe. Einstein was very excited when he learned about this expanding or pulsating universe model. He thinks his model is not good and should be abandoned. Lidman model is the correct model of the universe.
At the same time, Einstein declared that it was wrong to add the cosmological term to the field equation of general relativity. The field equation should not contain cosmological terms, but should be the same as before. However, cosmic terms are like the devil released from the bottle in the Arabian Nights, which can never be taken back. Later generations ignored Einstein's opinion and continued to discuss the meaning of cosmic terms. Today, there are two kinds of field equations of general relativity, one contains no cosmological term and the other contains cosmological term, both of which are in the application and research of experts.
As early as 19 10 years ago, astronomers found that the spectra of most galaxies had red shifts and some galaxies had purple shifts. These phenomena can be explained by Doppler effect. When we receive the light from a light source far away from us, we will feel that its frequency decreases, its wavelength becomes longer and its spectral line shifts to a long wavelength. On the contrary, towards our oncoming light source, the spectral line will move in the direction of short wave and appear purple shift. This phenomenon is similar to the Doppler effect of sound. Many people have had the feeling that the oncoming train is particularly sharp and harsh, while the train leaving us is obviously dull. This is the Doppler effect of sound waves. We feel that the frequency of sound waves emitted by oncoming sound sources increases, while the frequency of sound waves emitted by sound sources far away from us decreases.
If we think that the red shift and purple shift of galaxies are Doppler effects, then most galaxies are far away from us, and only a few galaxies are close to us. Subsequent studies have found that those purple-shifted galaxies that are close to us alone are all in our own local cluster (the cluster of galaxies where our Milky Way is located is called the local cluster). Most galaxies in this cluster are red-shifted and a few are purple-shifted. The galaxies in other galaxy clusters have all undergone red shifts.
1929, American astronomer Hubble summarized some observation data at that time and put forward an empirical rule, that is, the red shift of galaxies outside the river (that is, other galaxies outside our milky way) is directly proportional to their distance from the center of our milky way. Because the red shift of Doppler effect is proportional to the speed of light source, the above law is also expressed as follows: the retrogression speed of galaxies outside the river is proportional to their distance from us:
V = high definition
Where V is the retrogression speed of extragalactic galaxies, and D is their distance to the center of our galaxy. This law is called Hubble's law, and the proportional constant H is called Hubble's constant. According to Hubble's law, all extragalactic galaxies are moving away from us, and the farther away from us, the faster they escape.
The law reflected by Hubble's law coincides with the theory of cosmic expansion. The purple shift of a single galaxy can be explained in this way. The galaxies in this cluster revolve around their same center of gravity, so there will always be several galaxies close to our galaxy at a certain time. This purple shift phenomenon has nothing to do with the overall expansion of the universe.
Hubble's law greatly supports Lidman's model of the universe. However, if you look at the data chart used in Hubble's Law, people will be surprised. In the relation diagram of distance and redshift, the points marked by Hubble are not concentrated near a straight line, but scattered. How dare Hubble conclude that these points should be drawn in a straight line? One possible answer is that Hubble grasped the essence of the law and put aside the details. Another possibility is that Hubble knew the theory of cosmic expansion at that time, so he boldly thought that his observations were consistent with the theory. After that, the observation data became more and more accurate, and the points in the data map became more and more concentrated near the straight line. Hubble's law was finally confirmed by a large number of experimental observations.
4. Is the universe finite or infinite?
Now, let's go back to the previous topic. Is the universe finite or infinite? Advantage or no advantage? In this regard, we discuss this issue from the perspectives of general relativity, big bang universe model and astronomical observation.
The universe that satisfies the cosmological principle (three-dimensional space is homogeneous and isotropic) must be boundless. But whether to limit it or not should be discussed in three situations.
If the curvature of three-dimensional space is positive, then the universe will be infinite. But it is different from Einstein's infinite static universe, it is dynamic, will change with time, constantly pulsating, and can not be static. The universe began to explode and expand from the singularity with infinitely small space volume. The material density, temperature, space curvature and four-dimensional space-time curvature of this singularity are infinite. In the process of expansion, the temperature of the universe gradually decreases, and the density, spatial curvature and curvature of spacetime of matter gradually decrease. When the volume expands to the maximum, it will turn into contraction. In the process of shrinkage, the temperature rises again, and the density, spatial curvature and curvature of spacetime of matter gradually increase, finally reaching a novel point. Many people think that the universe will begin to expand again after reaching the novelty point. Obviously, the volume of this universe is limited, and it is a pulsating and limited universe.
If the curvature of three-dimensional space is zero, that is, three-dimensional space is straight (there is matter in the universe, and four-dimensional space-time is curved), then the universe has an infinite three-dimensional volume from the beginning, and this initial infinite three-dimensional volume is singular (that is, infinite singularity). The Big Bang started from this "infinite" singularity. The explosion did not occur at a certain point in the initial three-dimensional space, but at every point in the initial three-dimensional space. That is, the big bang happened on the whole "infinite" singularity. This "infinite" singularity. The temperature is infinite, the density is infinite, and the curvature of spacetime is infinite (the curvature of three-dimensional space is zero). After the explosion, the whole "singularity" began to expand and became a normal nonsingular spacetime, and the temperature, density and curvature of spacetime gradually decreased. This process will continue. This is an incomprehensible image: an infinite volume is constantly expanding. Obviously, this universe is infinite, it is an infinite universe.
The negative curvature of three-dimensional space is similar to the zero curvature of three-dimensional space. The universe has an infinite three-dimensional volume from the beginning, and this initial volume is also strange, that is, the three-dimensional "infinite" singularity. Its temperature and density are infinite, and its three-dimensional and four-dimensional curvature are infinite. The big bang happened on the whole singularity. After the explosion, the infinite three-dimensional volume expands forever, and the temperature, density and curvature gradually decrease. This is also an infinite universe, or an infinite universe.
So, which of the above three situations does our universe belong to? Is the spatial curvature of our universe positive, negative or zero? This problem is determined by observation.
The study of general relativity shows that there is a critical density ρc for matter in the universe, which is about three nucleons (protons or neutrons) per cubic meter. If the density ρ of matter in our universe is greater than ρc, the curvature of three-dimensional space is positive, and the universe is finite and infinite; If ρ is less than ρc, the curvature of three-dimensional space is negative and the universe is infinite. Therefore, by observing the average density of matter in the universe, we can determine what kind of universe we belong to, whether it is finite or infinite.
In addition, there is a standard, that is, the deceleration coefficient. The redshift of extragalactic galaxies reflects the deceleration expansion, that is to say, the speed of extragalactic galaxies away from us is decreasing. From the speed of deceleration, we can also determine the type of the universe. If the deceleration factor q is greater than 1/2, the curvature of the three-dimensional space is positive, and the universe will shrink when it expands to a certain extent; If q is equal to 1/2 and the curvature of three-dimensional space is zero, the universe will expand forever; If q is less than 1/2, the curvature of three-dimensional space will be negative and the universe will expand forever.
Table 3 lists the relevant situation:
Table 3
Decelerating factor of redshift of matter density in the universe; Expansion characteristics of three-dimensional space curvature universe type
ρ > ρ c q > 1/2 Positive finite infinite pulsation
ρ = ρ Cq = 1/2 Zero Infinity and Forever Infinite Extension.
ρ < ρ c q < 1/2 negative infinity expands forever.
We have two criteria to decide which universe we belong to. The observation results show that ρ < ρ 1/2, indicating that the spatial curvature of our universe is positive, and the universe is infinitely pulsating. When it expands to a certain extent, it will shrink back. Which conclusion is correct? Some people tend to think that the observation of deceleration factor is more reliable, and speculate that some dark matter in the universe may be ignored. If you find these dark matter, you will find that ρ is actually greater than ρ c, and others hold the opposite view. Others think that although the conclusions of the two observation methods are opposite, the spatial curvature obtained is not much different from zero, and the spatial curvature of the universe may be zero. However, to unify everyone's understanding, further experimental observation and theoretical scrutiny are needed. Today, we are not sure whether the universe is finite or infinite, but we can only be sure that the universe is infinite and is expanding now! In addition, we also know that the expansion began about 65.438+0 billion-20 billion years ago, which means that our universe originated about 65.438+0 billion-20 billion years ago.
5. Einstein's model of the universe
According to the physical theory, the ideas and speculations about the universe put forward under certain assumptions are called the universe model.
Einstein, a famous scientist, established the physical theory of general relativity in 19 15. The theory holds that there is no absolute space and absolute time in the universe, and both space and time are inseparable from matter, and both space and time are affected by matter; Gravity is the effect of space bending, which is determined by the existence of matter. Einstein applied his theory to the study of the universe. 19 17 published a paper "cosmological investigation based on general relativity". He applied the gravitational field equation of general relativity to the whole universe and established the model of the universe.
At that time, scientists generally believed that the universe was static and did not change with time. Although a few years ago, American astronomer shriver discovered the red shift of the spectral lines of galaxies outside the river (obviously this is a challenge to the static universe), the news did not reach Europe, because it was World War I.. Therefore, Einstein, like most scientists, believed that the universe was static. Einstein wanted to get the answer that the universe is static, uniform and isotropic from the gravitational field equation. But the solution he got is unstable, which shows that the total distance is not constant, but changes at any time. In order to get a stable solution in space, Einstein artificially introduced a term called "cosmological constant" into the gravitational field equation to make it act as a repulsive force. Einstein put forward a finite and infinite static universe model, which we call Einstein universe model. For the sake of understanding, it can be compared to a two-dimensional sphere in a three-dimensional space: the sphere has a limited area, but there is no boundary or center along the sphere, and the sphere remains stationary. A few years later, Einstein regretted adding a cosmological constant to his model, calling it the biggest mistake he made in his life.
The latest discovery: the companion star of strange stars in the Milky Way appears.
Scientists used NASA's far ultraviolet spectrometer to detect the companion star of Eta carina for the first time. Eta carina is the heaviest and strangest star in the galaxy. It is located 7500 light years away from the earth and can be clearly seen with the naked eye in the southern hemisphere. Scientists believe that Eta carina is an unstable star that is rapidly declining.
For a long time, scientists have inferred that it should have a companion star, but there has been no direct evidence. Indirect evidence comes from the regular change of its brightness. Scientists found that the brightness of Eta in the visible light, X-ray, radio wave and infrared band showed a regular repetitive pattern, so it was speculated that it might be a binary star system. The strongest evidence is that every five and a half years, the X-rays emitted by Etta system in the ship's base will disappear for about three months. Scientists believe that the temperature of Eta Carina is too low to emit X-rays, but it emits gas particles at a speed of 300 miles per second, which collide with particles emitted by its companion star, thus emitting X-rays. Scientists believe that the reason why X-rays disappear is that Eta Carina blocks these X-rays every five and a half years. The last X-ray disappearance began on June 29th, 2003.
Scientists infer that the distance between Eta carina and its companion star is 10 times that between the earth and the sun, because they are too close and too far away from the earth to be directly distinguished by telescopes. Another method is to directly observe the light emitted by the companion star. However, eta carina's companion star is much darker than itself. In the past, scientists tried to observe it with ground-based telescopes and Hubble telescopes, but both failed.
Lin Xiawei Yiping, a scientist at Catholic University in the United States, and her collaborators used the satellite of the Far Ultraviolet Spectrometer to observe this companion star, because it can observe ultraviolet rays with shorter wavelength than the Hubble telescope. They observed far ultraviolet rays on June 10 and June 17, but they disappeared on June 27th, two days before the X-rays disappeared. The observed far ultraviolet rays come from the companion star of Eta carina, because the temperature of Eta carina is too low to emit far ultraviolet rays. This means that eta carina blocks X-rays and companion stars. This is the first time that scientists have observed the light emitted by Eta companion star in carina, thus confirming the existence of this companion star.
A star with three suns.
According to Xinhua News Agency 14, according to the report in Nature published by 14, American astronomers discovered a strange galaxy with three stars at a distance of 149 light years from the Earth. On this galaxy planet, three suns can be seen in the sky.
Astronomers of California Institute of Technology reported in this journal that they found three stars in the HD 188753 galaxy of Swan constellation. A star in the center of the Milky Way is similar to the sun in the solar system, and the planets next to it are at least 14% larger than Jupiter. The distance between the planet and the central star is about 8 million kilometers, which is one twentieth of the distance between the sun and the earth. Two other stars in the Milky Way galaxy are in the periphery. They are not far from each other and also revolve around the central star.
Most of the galaxies in the Milky Way are single galaxies or binary systems, and galaxies with more than three stars are called galaxy clusters, which is rare.
Stars are not evenly distributed in the universe. Most stars will be influenced by each other's gravity, forming a star aggregation system, such as binary stars, Samsung, and even star clusters, as well as star groups such as galaxies composed of hundreds of millions of stars.
Astronomers found that the birth of life in the universe is a common phenomenon.
Recently, the scientific research team of NASA looking for evidence of the existence of life materials outside the earth found that some organic chemicals that play a vital role in actual biochemical reactions are ubiquitous in the vast universe outside our earth. The research results show that there are living things in the depths of the universe, or there are chemical reactions that breed living things, which is a common phenomenon in the vast universe.
The above research comes from a space biology research group at the Ames Research Center of NASA. Douglas Higgins, a scientist who works in the group, said: "According to the latest research results of the research group, a class of compounds that play a vital role in biochemistry exist widely and massively in the vast space." As one of the main members of the research group of outer space biology, Douglas Higgins published their latest research results as the first author in the journal Astrophysics published in June +654381October+10/October, 5438.
When describing his research results, Higgins introduced: "With the recent observation results of NASA's Spitzer Space Telescope, astronomers have found a complex organic compound-polycyclic aromatic hydrocarbons (PAHs) everywhere in our galaxy. However, this discovery only attracted the attention of astronomers at first, but did not attract the interest of astrobiologists who studied outer space creatures. Because for biology, the existence of ordinary polycyclic aromatic hydrocarbons does not explain any substantive problems. However, in a recent analysis, our research group was surprised to find that the molecular structure of these polycyclic aromatic hydrocarbons seen in the universe contains' nitrogen '(N) element. This unexpected discovery has greatly changed our research. "
Another member of the research team, Louis Eland Mandela, an astrobiologist from the Ames Research Center of NASA, said: "Including DNA molecules, the participation of nitrogen-containing organic molecules is a necessary condition for most chemicals that constitute life. Give a typical example of nitrogen-containing organic matter in the sense of living matter, like chlorophyll, which we are familiar with, which plays a key role in plant photosynthesis. Chlorophyll molecules are rich in nitrogen-containing polycyclic aromatic hydrocarbons (PANHs). "
According to reports, in the research work of the research team, in addition to the observation data obtained from the Spitzer telescope, the researchers also used the observation data of the space infrared astronomical observation satellite of the European Space Agency. In the laboratory of Ames Research Center of NASA, the researchers comprehensively analyzed the molecular structure and chemical composition of this kind of special polycyclic aromatic hydrocarbons by using infrared spectral chemical identification technology, and found evidence of nitrogen in it. At the same time, scientists used computer technology to simulate and analyze nitrogen-containing polycyclic aromatic hydrocarbons (PAHs) ubiquitous in these universes.
Louis Elam Mandela also said: "In addition to the above analysis conclusions, the more dramatic discovery is that the observation of Spitzer Space Telescope also shows that the interstellar matter around some dying stars in the universe contains this special nitrogen-containing polycyclic aromatic hydrocarbons. In a sense, this discovery seems to tell us that in the vast starry sky of the universe, even if death comes, it breeds the fire of new life. "
The biggest scientific breakthrough this year: the expansion of the universe and the discovery of dark energy.
By analyzing the cluster of galaxies (the point on the left in the picture), astronomers of Si Long Digital Sky Observation Program determined that dark energy is driving the expansion of the universe.
According to the British "Guardian" report, confirming that the universe is expanding is the most important scientific breakthrough this year.
It is reported that nearly 73% of the universe is composed of mysterious dark energy, which is a kind of anti-gravity. The discovery of dark energy was rated as the most important scientific breakthrough this year by the American magazine Science published in June, 5438+09. Through telescopes, humans have discovered nearly 200 billion galaxies in the universe, and there are about 200 billion planets in each galaxy. But all these add up to only 4% of the whole universe.
Now, on the basis of new space exploration, astronomers have made clear at least part of the situation through careful study of 1 10,000 galaxies. About 23% of cosmic matter is "dark matter". No one knows what they are because they can't be detected, but their mass greatly exceeds the sum of the visible universe. And nearly 73% of the universe is newly discovered dark energy. This strange force seems to be accelerating the expansion of the universe. British astronomer Sir martin rees called this discovery "the most important discovery".
This discovery is the result of Orbital wilkinson microwave anisotropy probe (WMAP) and Si Long Digital Observatory (SDSS). It has solved a series of long-standing disputes about the age, expansion speed and composition of the universe. Astronomers now believe that the age of the universe is 65.438+037 billion years.