How big is the universe? What's out there?

What is beyond the universe? How big is the universe? I believe many people have tried to find the answer to this question. In fact, physicists have studied the universe for a long time. What it looks like outside the universe is still unknown. I believe that reading the following content may help you find the answer.

First, we need to know what the universe is. The universe is the general name of all things, and it is the unity of time and space. The universe is a material world, which exists objectively regardless of human will and is in constant movement and development. It has no beginning or end in time and no boundary or end in space. The universe is diverse and unified; Diversity of material manifestations; Unity lies in its materiality. The universe is a unity composed of space, time, matter and energy.

The origin of the universe is an extremely complicated problem. The universe is a material world, which is in constant movement and development. For thousands of years, scientists have been exploring when and how the universe was formed. Today, many scientists still believe that the universe was formed by a big bang about 654.38+037 billion years ago. The matter and energy stored in the universe gather together and condense into a very small volume, with extremely high temperature and density, which instantly produces great pressure, and then there is the Big Bang. The reaction principle of this big bang is called quantum physics by physicists. The big bang dispersed the matter, the space expanded continuously, and the temperature dropped accordingly. Later, it appeared in all galaxies, stars, planets and even life in the universe.

Outside the Hubble volume

In some ways, we can say with certainty that there are more universes besides the universe. Astronomers believe that space is infinite, and the space outside the universe is as full of energy and galaxies as the observable universe. If so, then what exists outside the universe becomes a very strange question.

Besides the size of Hubble, you will not only find more different planets-you can see anything (see 42). Yeah, anything. If you look far enough, you will see you in another universe. He ate oatmeal instead of eggs for breakfast today. You will see another you who didn't eat breakfast. You'll see you get up before dawn and rob a bank. In fact, cosmologists believe that if you look far enough, you will enter another Hubble volume-a perfect replica of the universe we live in. In another universe 10 188 meters away, there is a person exactly like you doing exactly the same thing. This sounds unlikely, but the concept of infinity is even more infinite than infinity itself. [Page]

Undercurrent galaxy cluster

In 2008, astronomers found that the mass of matter in the universe seemed to be moving in the same direction at a very high speed, which could not be explained by any gravitational model in the visible universe. The speed reaches 2 million miles per hour (32 1.8 million kilometers). The new observation results of 20 10 confirmed this phenomenon-undercurrent. This movement of matter challenges all predictions about the overall distribution of matter in the universe after the Big Bang. One of the possible reasons: the gravitational effect of the huge mass structure outside Hubble volume on the universe. This means that there are uncertain structures in the infinite universe outside our observation range. These structures may appear in any form, they may be a combination of a large piece of matter and energy, and their volume is beyond human imagination, or they may be strange bending funnel-shaped gravity from other universes.

The universe is an infinite bubble.

After all, the universe outside the Hubble volume is still the universe, but we just can't see it. These places follow the same physical laws and constants as the universe we observed. Since BIGBANG, the universe has been expanding, which will lead to bubbles in space. Inside each bubble is a universe that stops expanding, and each bubble has its own physical laws. This theory holds that the universe is infinite and the bubble itself is infinite (you can choose an infinite number from an infinite set or include it in this infinite set). Even if you can escape from the bubble boundary, the space outside the bubble is still expanding, and no matter how hard you chase it, you can't explore other bubbles. [Page]

Black holes breed cosmology.

Physicist Lee smolin put forward a new theory that every black hole in our universe will create a new universe. And the physical laws of each new universe are slightly different from those of the previous universe. Smolin put forward the cosmology of natural selection. If some laws of physics can produce black holes more frequently, more universes can be created. At the same time, the universe without black holes can only wait for death.

There are many parallel universes.

There are too many theories about parallel universes. Among the most accepted theories at present, one is an evolutionary version of string theory: people think that several membranes vibrate in other dimensions. Simply put, these rippling membranes vibrating in the dimension of 1 1 are other universes outside our universe. The ripple motion effect can help explain the material distribution in the observed universe. This theory holds that gravity is special because it leaks from other universes in other dimensions to this universe in our dimension. This can also explain why gravity is so weak compared with other basic forces.

How big is the universe? ?

To know how big the universe is, please try to put a coin in front of you. Suppose this small coin is our sun, then another coin representing the nearest star: proxima centauri should be placed about 563 kilometers away. For readers living in China, such as Shanghai readers, this second coin will almost be placed in Shandong or Anhui province, while for residents of some small countries, this coin may have been placed abroad. [Page]

This is just the sun and the nearest star. When you try to simulate a larger space, it will be a lot of trouble. For example, relative to your coin sun, the diameter of the Milky Way will be about12 million kilometers, which is equivalent to 30 times the distance between the earth and the moon. As you can see, the scale of the universe is amazing, and it is almost impossible to measure it by the familiar distance scale in our life.

But this does not mean that the dream of measuring the universe is out of reach. Astronomers have found some effective methods to measure the scale of the universe in their long-term work and research. Below we will show you the relevant content:

1 the size of the universe

We don't live in the center of the universe, but we do live in the center of the Hubble volume, a sphere with a diameter of about 93 billion light years.

No one on this planet knows how big the universe is. It may be infinite, or it does have some kind of boundary, which means that if you travel long enough, you will eventually return to where you started, just like on the earth, similar to traveling on the surface of a sphere.

Scientists have different opinions on the specific shape and size data of the universe, but at least they can calculate very accurately on one point, that is, how far we can see. The speed of light in vacuum is a constant. Since the universe has been around 65.438+037 billion years since its birth, does this mean that we can only see the farthest place of 65.438+037 billion light years?

The answer is wrong. One of the strangest characteristics of the universe is that it is constantly expanding. And this expansion can be carried out at almost any speed-even faster than the speed of light. This means that the farthest celestial bodies we can observe are actually much closer than they are. With the passage of time, due to the overall expansion of the universe, all the galaxies will be farther and farther away from us, until finally they leave us with an empty space.

Strangely, as a result, our observation ability has been "enhanced". In fact, the farthest galaxy we can observe is 46 billion light years away. We don't live in the center of the universe, but we do live in the center of Hubble volume, a sphere with a diameter of about 93 billion light years. [Page]

Filled with galaxies.

This photo is one of the deepest images obtained by NASA Hubble Space Telescope, and it is also one of the deepest images obtained by NASA Hubble Space Telescope.

This photo is one of the deepest images obtained by NASA's Hubble Space Telescope. Scientists aim the Hubble telescope at a small area in the sky for a long time-for months, capturing as many faint spots as possible. The above image is partially enlarged, and the complete image is the following image, including 10000 galaxies. Zooming in locally, we can see the details of some galaxies.

A complete image, a complete image

When you look at these distant galaxies, you may not realize that you are looking at the distant past. All the galaxies you see were like 654.38+03 billion years ago, which is almost the end of time. If you prefer the description of space, then these galaxies are 30 billion light-years away.

The universe is expanding, but at the same time, the measurement accuracy of scientists on the scale of the universe is also improving. They soon found an excellent way to describe the distance between distant objects in the universe. With the expansion of the universe, the wavelength of light propagating in the universe will be lengthened, just like a rubber band is lengthened. Light is an electromagnetic wave. For it, a longer wavelength means being close to the red band in the spectrum. So astronomers use the word "redshift" to describe the distance between celestial bodies. Simply put, it describes how much expansion and stretching the light beam has experienced in space after it has been emitted from the celestial body. The farther away the celestial body is, of course, the more the wavelength of light wave is lengthened during propagation, the redder the light is.

If you use this description method, you can say that the distance between these distant galaxies is about the redshift value Z=7.9, and astronomers will immediately understand what you mean by the distance scale. [Page]

The farthest celestial body

The farthest celestial body, the farthest celestial body

The inconspicuous red blur in the middle of this image is actually a galaxy, which is the farthest celestial body observed by human beings so far. This photo was taken by NASA's Hubble Space Telescope. This galaxy only existed in the Big Bang 480 million years ago.

The redshift value of this galaxy is about 10, which is equivalent to 31500 million light years from the earth. It seems that this galaxy is very lonely, and no galaxies of the same period have been found around it. This is in sharp contrast to the situation about 650 million years after the Big Bang, during which astronomers discovered about 60 galaxies. This shows that although this short 200 million years is only a blink of an eye for the universe, it is in this short time that a large number of small galaxies have gathered to form large galaxies.

But what needs to be pointed out here is that astronomers have not fully confirmed the distance value of this celestial body, which means that its actual distance may be closer than now imagined. Before NASA's next generation James Webb space telescope is launched to replace Hubble telescope, scientists will have to estimate it under the condition of insufficient data. [Page]

Farthest distance

The farthest distance, the farthest distance

The farthest light that astronomers can observe is called cosmic microwave background radiation (CMB). These are the oldest photons that reached the earth, and they were born almost at the moment of the Big Bang. In a short time after the big bang, the universe was very small, so it was quite crowded and the density of matter was too high for light to travel long distances.

But about 380 thousand years after the birth of the universe, the universe became big enough for the first time, and light could spread freely. The light emitted at this time is the oldest light we can observe today and the first dawn of the universe; It exists in every direction of the universe, no matter which direction you point the telescope, you can observe its existence. The cosmic microwave background radiation is like a wall. You can only see the scenery on this side of the wall as much as possible, and there is no way to cross it.

So how did these original cosmic lights become microwaves? This is still because of the expansion of the universe. With the expansion of the universe, the wavelength of light waves emitted at that time gradually lengthened. After such a long time (65.438+03.7 billion years), their wavelengths have been stretched to an incredible extent. With the expansion and cooling of the universe, the residual temperature of this radiation is only about -270 degrees Celsius, which is the famous 3K background radiation. The distribution of this radiation presents amazing isotropy, and the difference is less than 65438+ 1/10000.

And if one day humans can finally make high-sensitivity neutrino detectors, then we can finally break through the wall of cosmic microwave background radiation and see the scene where neutrinos appear behind, which is the so-called "cosmic neutrino background". Unlike photons, for neutrinos, ordinary matter is almost transparent, and they can easily pass through the earth, the sun and even the whole universe. It is precisely because of this characteristic that once we can decode the information carried in neutrinos, we can go back to the scene just a few seconds after the Big Bang. [Page]

Butterfly map of galaxy 5

Galaxy butterfly map

Astronomers observe the universe. They noticed that the distribution of galaxies in the universe was not random. Because of gravity, galaxies tend to approach each other, thus forming huge aggregates, such as galaxy clusters, superclusters, large-scale flaky structures and even so-called giant walls.

Astronomers began to record the positions of these galaxies in three-dimensional space, and they quickly succeeded in making a three-dimensional distribution map of galaxies in a relatively close range, which was an amazing achievement. Most of these surveys focused on the range of 7 billion light-years from the earth, but in the process, they also found many quasars, which are strange objects with amazing brightness in the universe, from the early universe, and their distance may be more than four times that of 7 billion light-years.

Of all these efforts, Sloan Digital Sky Survey (SDSS) is probably the largest. Astronomers involved in this project have basically completed the observation of 1/3, and recorded the precise position information of more than 500 million celestial bodies in the process. The map here in this paper comes from another survey project: 6dF Galaxy Survey, which is the third largest survey project at present. The reason why many places in this image are missing is that we can't observe many sky areas because of the obstruction of the Milky Way. [Page]

Supergalaxy cluster near 6

Adjacent supercluster

Astronomers will know more about it in space near the earth. We now know that there is an ocean of supercluster about10 billion light-years away from the earth. These are a large number of member galaxies held together by gravity.

Our Milky Way itself is a member of the virgo supercluster, and this supercluster is located in the center of this image. In this huge supercluster structure, our galaxy is nothing special, it is just an ordinary member galaxy located in a corner. Dominant in this magnificent structure is the Virgo galaxy cluster, which is a huge group of more than 65,438+0,300 member galaxies with a diameter of over 54 million light years.

There is also a supercluster worthy of attention, that is, the late constellation supercluster, because its location is right in the center of the Great Wall. The Great Wall in the north is an unimaginable giant structure with a diameter of about 500 million light years and a width of about 300 million light years. The largest supercluster near our milky way galaxy is the clock supercluster, with a diameter of over 500 million light years. [Page]

7 Dark matter and dark energy

Dark matter and dark energy Dark matter and dark energy

Another surprising fact of this universe is that we can't see most of the components in the universe at all. Dark matter is a mysterious existence. Scientists think it exists everywhere in the universe, but we can't see it or touch it. They do not interact with light or any kind of electromagnetic wave, which is the basic tool for human beings to explore the universe. However, it will produce gravity, and scientists can feel their existence through its gravitational effect on the surrounding space.

Yes, we can feel that dark matter does exist. For example, in virgo supercluster where we live, the mass is 15 times that of the sun, but the luminosity of the entire supercluster is only 3 trillion times that of the sun. This means that the luminosity of virgo supercluster is about 300 times smaller than its quality should be. This fact is difficult to explain, but it is not surprising if we consider that there are a lot of dark matter with mass but no light.

In fact, according to the calculation results, the content of dark matter in the universe is five times that of ordinary matter we usually see. But dark matter, though powerful, is still not enough to rule the universe. The power that really dominates our universe comes from another mysterious substance: dark energy. Ordinary matter and dark matter have one thing in common, that is, they all have mass, and both have gravitational influence on the surrounding space. In other words, their function is to gather matter, slow down expansion, and even eventually shrink the universe. However, when scientists observe the universe and try to distinguish whether it is decelerating or contracting, they are horrified to find that the fact is completely beyond their expectation-the universe is not contracting or decelerating at all, but accelerating its expansion! There is no doubt that there is an unknown and extremely powerful force, which not only resists the gravitational effect of all ordinary matter and dark matter in the whole universe, but also promotes the accelerated expansion of the whole universe. The discovery of dark energy has just been awarded this year's Nobel Prize in Physics, but despite such great progress, scientists still don't know what dark energy is. Now the theory about this subject is almost equivalent to "waiting for it", waiting for a more perfect theory in the future to win the laurel of successfully explaining the nature of dark energy. [Page]

8 the web of the universe

The web of the universe.

The results of the galaxy survey show that our universe seems to present a "bubble net" structure. Almost all galaxies are distributed in a narrow "fiber belt" with a huge hole in the middle, which is called a "giant hole" in astronomy. These huge caves are huge, some of which can reach 300 million light-years in diameter, and there is almost nothing in them. But this is not true, because although there seems to be nothing there, it is actually full of dark matter.

The picture here is a computer simulation result, which shows that our universe presents an optical fiber network structure, in which nodes, optical fiber ribbons and layers are distributed. The origin of this complex structure comes from the tiny ripples in the cosmic microwave background radiation, which is the embodiment of the tiny change of density. With the expansion of the universe, these tiny high-density areas gradually attract more substances to gather in them. This effect lasted for tens of billions of years, and the result was amazing-it created the universe we see today. [Page]

9 test the universe model

Test the universe model, test the universe model.

In 2005, an international team of astronomers tried to test whether the existing cosmological theory was correct. They implemented a simulation plan called "Millennium Action". In the computer, they simulated 1000 billion particles in a cubic space with a side length of 2 billion light years. If we act on them according to our existing theory, can we get some expected results?

In this simulation experiment, ordinary matter, dark matter and dark energy are considered, and the large-scale structure of the universe is successfully reproduced from chaos, which is similar to what we observed today. During the simulation operation, researchers witnessed the appearance of massive black holes in the universe, and powerful quasars emitted strong radiation. About 20 million galaxies also appeared in the simulation results. As shown in the figure, the researchers found that the simulation results produced a state very similar to the real universe we observed.