If we can run near the black hole, we will find that it turned out to be colorful | Zhang Fan

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In addition to the observation, the black hole is very interesting,

Can bring us a very wonderful photo,

It is actually very suitable for thinking tests,

It is something that can promote scientific development out of thin air.

Zhang Fan · Associate Professor of Astronomical Department of Beijing Normal University

Gezhi Tao Tao No. 38 | April 29, 2019 Beijing

Hello everyone, I am Zhang Fan, from the Astronomical Department of Beijing Normal University.

Gravity is not force, but the expression of time and space bending

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If you want to understand why the black hole looks like a donut, we must first know the general theory of relativity.

The birth of the general theory of relativity can be traced back to the Pizza diagonal tower. Galileo threw a heavy ball and a light ball from the inclined tower at the same time. They finally landed at the same time, and the results were unexpected. Before doing experiments, people do not think such results will occur.

Pisa Land Tower Experiment

Later, Einstein thought about the results of the experiment and thought of a very interesting thing. He realized that gravity was completely different from other forces.

Such as electromagnetic force. If two of the same objects bring different charge, put them in the electric field, one will accelerate quickly, one will accelerate slowly, and then the two of them will be separated. Through this method, we can know whether there is an electric field somewhere.

However, under the action of gravitational field, the two objects will always fall synchronously. We have no way to distinguish whether they fall because of the role of the gravitational field, or in fact, these two objects are floating in space, but it is just that we accelerate the elevator as a reference object. sports.

In this case, Einstein thinks that if these two cases cannot be distinguished under any experiment, then as an experimental science, physics should determine that they are the same thing.

In other words, gravity is not force, and it does not accelerate objects. Most of the gravitational effects experienced in life are mostly because people have chosen strange references.

Having said that, it is not that gravity has no effect at any time. Of course, gravity exists, but it is not a normal force. What is not strong is straight. However, in large scale, such as around the earth, the direction of gravity in various places is biased towards the ground, and the direction is different.

Two elevators that fall

For example, the thinking experiments displayed in this picture, the two elevators were in parallel, but later they would hit together because the role of gravity would guide them in the direction of the ground. Therefore, gravity can be verified with experiments.

If the gravity is not force, the unsatisfactory object should move along the line. The two objects along the straight line are parallel to the beginning. Why is it not parallel to walk behind?

Obviously, this situation cannot occur on the plane, and the objects parallel to the plane will always be parallel. But if it is on a curved curved surface, this situation may happen.

At the beginning, the two black lines and yellow lines were the same, so at the beginning, the two black lines were parallel. But the two black lines slowly walked to both ends of the earth, and they would hit them together.

At this time, Einstein thought that gravity was not power, and gravity actually represents the bending of time and space.

The object takes straight lines, and in any shape, it means that objects can experience the shortest line in this shape. If the shape itself is strange, these lines will also show strange features.

We can now understand why in an elevator, we can't measure whether the gravity exists. But at a large scale, when the gravitational field changes, the effect of gravity is reflected.

Imagine that you are a ant, in the small circle in the picture, you can't actually distinguish whether you are on the plane above, or on the surface below. This is a bit similar to that we are on the earth, but we don't know that the earth is round. Only when we pull ourselves, put them on a large scale, and see the changes in the gravitational field, we will know that our time and space are bent, and we are on a curved side. The changes in this gravity are also called tide power. It can be said that the effect of gravity is mainly reflected through tide power. The first -order effect of gravity itself does not exist, not a force.

Since gravity is a manifestation of time and space bending, the substance that generates gravity must be bent in time and space. How can the material bend the time and space? If the gravity is not power, I jump now, why don't I fly to the space?

The edge of black holes -event vision

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A fish desperately wants to swim out of the waterfall

In fact, you can imagine this, the space is like a waterfall, the water continues to flow down, the faster the flow rate. Even if I jumped up, I was rushed down by the waterfall.

In other words, in the universe, if there is a large quality object in a small range, the flow rate of the waterfall around this object will be very fierce, then the fish that swims at the fastest speed will not be able to swim.

Einstein once said that the fastest speed in the universe is the speed of light. If a fish with a speed swim can not escape, then this waterfall is called a black hole, and the margin of the black hole is called the events of the event.

Ship test on the edge of the waterfall

Outside the incident, although light will not be sucked in, it will also be affected. Just like the boat in the picture, even if people work hard along the line, because the horizontal water flow is fast, it will still be dragged by being affected.

Bended light around the black hole

Therefore, the light around the black hole will not only bend, but also around the black hole. The effect of black holes is the same as the effect of glasses. The reason why glasses can be enlarged because light has biased through glasses.

Gas around the black hole

We can imagine the black hole as a big haha ​​mirror. At this time, if a hot gas is placed around the black hole and let it turn around the black hole, you will see that it has many shadows, but there is actually only one gas. From different perspectives, we look at the black hole, and it will map this gas to a strange image.

Like a black hole in donuts

Understand the content mentioned above, and then look at the picture, we probably understand what is going on. This photo like a donut, the black hole is actually inside the black position in the middle, the circle around it is the signal emitted by the material outside the black hole, and the radio signal refracted by a black hole like a Haha mirror.

Of course, the people's naked eyes are invisible, because people can't see microwaves. This picture is actually a sign of the signal intensity.

If humans can really run near the black hole to watch, you will see that the black hole is colorful. Color does not mean that it looks good, but because of these gases around the black hole, the temperature is different in different places, and the color emitted is different, so it will show the color effect.

Gas around the black hole emit different glory due to different temperatures

But this picture is imagined, and it is processed according to a large amount of data. In fact, it is still very difficult to take photos of the black hole donuts displayed earlier. Because this is actually the silhouette of the black hole, we have to see the black circle in the middle to say that it is a black hole.

The black hole body in the photo is 55 million light years, and the black hole itself is very small, which is basically a little on the sky. It has dark spots in the middle, and people want to distinguish the light and darkness at a small point. This is very difficult. If it is blurred, it is a highlight, and there are many highlights in the sky.

Look at the distant black hole with interference arrays

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If you want to get such fine photos, you must have a particularly high angle resolution. So how can we get such a high angle resolution?

Obtain high angle resolution by interference array methods

We obtain high angle resolution by interfered by interference arrays. The signal of the black hole is spread at a certain moment, and the time they reach the various radio telescopes on the earth are different. The time difference is obviously related to the angle between the red dotted line and the red solid line in the picture. Therefore, the use time difference can extract the sources of these signals with interference methods. At the same time, the time difference is directly proportional to the length of the real line.

In other words, if the distance between the two telescopes is particularly long, we will get a relatively large delay, and this time delay will tell us which direction the signal is from. In the case where the accuracy of the instrument is unchanged, we can get a particularly high angle resolution.

This is why the radio telescope array involved in the shooting black hole covers the telescope from different places from Greenland to Antarctica, and the distance between the earth reaches the diameter of the earth. Among them, the sensitivity of a Chilean telescope array is particularly high, and it is also a very important array.

We can use large instruments to watch a large black hole in the distant interstellar, and it is possible that some high -end instruments can create a small black hole on the earth.

Can we create black holes?

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The old gentleman is Kip Thorne (Kip Thorne), a scientific consultant of the movie "Star Cross". He raised a conjecture: If you give an object, make a particularly small hula circle according to its quality, and then let the hula circular rotation. During the transfer process, this object can always be included. In other words, objects must be contained in this object in all dimensions and directions. Then, this object will definitely form a black hole.

Large particle collision machines can focus very high energy, that is, a large quality concentrated in a small range, so it is possible to create a black hole according to this conjecture.

If we really make black holes with a particle collision machine, will it devour the earth?

This is impossible. First of all, it is difficult to form a black hole. This requires two particles to be particularly accurate, just hitting her head. If you do not modify the gravity on the tiny scale and introduce a high -dimensional space, it is actually difficult to do this.

Even after the black hole is generated, Hawking will evaporate, and the smaller the black hole will evaporate faster, the black holes will soon disappear. This "evaporation" statement was proposed by Hawking. Even though Hawking said wrong, the black hole does not evaporate, it can exist for a long time and stable, and will not devour the earth.

Although the gravity of the black hole is strong, it can only be appreciated only where the black hole is particularly close. When it is far from the black hole, the gravity of the black hole is actually no different from a basic particle of the same quality, and it will not swallow the distant objects. Basically, nothing can just go to the place where it is very close to the black hole.

These things around us are basically vacuum, because the basic particles look vacuum, and the size of the atomic nucleus and atoms is 100,000 times.

Even if scientists can create black holes, it is much smaller than the atomic nucleus, and there is basically nothing to "eat" to the place where the black hole is particularly close to the black hole. Therefore, the only thing that the black hole will do is to sink to the middle of the earth and "sit" quietly.

If you fall into the black hole, what experience will you have?

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Although we are not "dead" on the earth, we can often see the black holes in the movie. For example, the actor COOPER in Star Trek then jumped into the black hole.

In the film, when he passed the incident, he didn't feel anything, and then went in. This is because unless there is a tide power, according to the principle of equivalent, the object does not feel any when the object is free.

The tidal power of the large black hole is actually very weak. Although the gravity is strong, the size of the person is much smaller than the size of the black hole. In terms of human size, although the gravitational field of the black hole is strong, the black hole gravity has not changed and there is no tide power, so Cooper does not feel any discomfort.

Cooper falling into the black hole

Until he fell to the middle and approached the strange point, if his head fell down, he would be torn, and if he dropped horizontally, he would be flattened.

The heroine Brand in the film, also the role of Annie Hathaway. She sitting in the spacecraft in the spaceship actually couldn't see the cooper falling into the black hole. She would think that Cooper had been solidifying in the events of the event. Why is this so?

Hand -painted time and space map

Please see this hand -painted space -time map, the vertical representative time, the horizontal representative space, the real line represents the events of the event, the dotted line represents the strange point, and the arc represents the movement trajectory of Cooper.

We just said that the definition of the events of the event is where any light can never escape. In other words, light is exercising along the incident.

If you want to see COOPER, you must have light from the cooper and reach Brand's eyes. But because light cannot escape from the world's field of vision, the light inside can never reach Brand's eyes, and Brand will never know that Cooper falls into the black hole.

And the closer to the view of the incident, the more difficult it is to go outside, it takes longer. Brand will only see that Cooper goes slower and slower, and finally sticks to the incident's vision. From this point of view, the field of incident is really amazing.

But there are even more wonderful. This video shows the state of the merger of two black holes. The incident of the two black holes finally merged into a single event horizon.

Please pay attention to observation, when the two events are merging, just like two small hands are holding hands. Why are they so powerful? How do they know which direction do they want to reach out? How do you know what will happen in the future? How to make sure they can merge perfectly?

This actually involves another characteristic of the events of the event -predicting the future. The definition of the incident horizon is that the light "forever" cannot escape from the events of the event, so at a certain moment, it is not known whether it is in the event of the event. Only when the universe is dead can it know whether it is running away in the end. Therefore, the definition of the events of the event is limited to it that it is not determined by local physics.

Trousers

This picture depicts two small black holes merged into a large black hole. This picture is also called pants. In the process of merging the black hole, the quality of the black hole will actually be reduced because some energy is taken away by gravitational waves.

But Bekenstein and Hawking told us that the surface area of ​​the black hole is actually increasing. This conclusion sounds a bit violated, but it is true.

This situation exists only in the case of classic gravity. After we joined the quantum mechanics, another thing happened. The surface of the black hole could be reduced, and the black hole could eventually evaporate. This is why the small black hole mentioned before can eliminate the earth.

A variety of black holes in the eyes of scientists in different fields

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The definition of quantum mechanics on vacuum is based on the observer. The cooper in "Star Tranquil" sees vacuum and has nothing around. But in the spacecraft, Brand saw many particles around the black hole. The system composed of these particles has temperature, and the black hole will generate heat radiation, which is called Hawking radiation.

In the cosmic vacuum environment, there will be a pair of particles that are constantly produced, and they will cancel each other and disappear. The reason for this is because the principle is not accurate. The principle of inappropriate measurement believes that within a small time range, energy is not accurate, so energy does not need to be conservative.

You can create two particles, as long as they can offset and disappear in a short time, and return the energy back, everything is okay. Of course, in fact, when quantum mechanics is calculated, it will use another equivalent method, or it is assumed that the energy is conservative, but the energy value of these two particles is particularly strange. In this way, Quality Energy Equation E = MC 不 cannot be used.

However, if this particle occurs near the black hole, the situation will become more complicated. For example, one of the particles fell into the black hole, or in the black hole from the beginning, and the other was outside the black hole. The particles inside cannot be offset with the particles outside, and the outside particles can run away and take away the energy, so that the energy cannot be repaid to the vacuum. This account requires a black hole to repay it.

In the long run, the energy of the black hole will be taken away, and the black hole will gradually become smaller until it is blown up and disappeared. The particles running away are Hawking radiation.

Hawking has another wonderful place. It is pure black radiation, which is only related to the quality, rotation speed and charge of the black hole. It has nothing to do with the composition of the black hole.

If you throw the dictionary and throw a stone in, their impact on Hawking radiation is the same. We have no way to identify the dictionary or stone that was thrown through Hawking radiation.

This is not the same as the black body radiation of the sun. In fact, there are detailed details in the radiation of the sun, but people ignore them artificially. We used a freehand method to describe solar radiation with thermodynamics, and artificially ignored those information.

And Hawking's radiation has no details. It doesn't matter what information is. Until the black hole evaporation disappeared, the information disappeared.

However, the statement that the information does not see makes a group of people unacceptable, they are quantum physicists.

Do you know the name of this cat? "Xue Dingzheng's cat" is a very well -known thinking experiment in the field of quantum mechanics.

In this experiment, this cat is in a state of life and death. The quantum force learns to tell you what the probability of it is born and the probability of death.

But if you open the box to observe the cat, the cat's life and death will be solid, and the probability of the cat's life and death is gone. The physical entity used by quantum mechanics to describe the probability will suddenly change instantly. Of course, this kind of human behavior that changes physical entities instantly is a more ideal explanation.

With a modern explanation, the status of a cat is transmitted to you. One who sees a cat is at the same time as you see the cat dying, just like a cat at the same time and death. But you cannot communicate between these two, nor can it affect each other. This is called multiple world explanations.

Multiple world explanations do not mean that our time and space will split a lot of parallel universe, but in different states, you are actually living in the same time and space like the cat that is both born and dead.

Anyway, quantum mechanics requires a statistical explanation, then the number of probability corresponding to all possibilities is equal to 1, that is, the total probability is 100%. If I only tell you the corresponding number of a certain event is 0.9, but it does not tell if the number of all events adds up to 1, that is actually equivalent to nothing telling you. You have no way to speculate a useful probability. The loss of information in the black hole will cause this total to not necessarily be 1, but we don't know how much it is.

Therefore, quantum scientists hate the total probability of the total probability of information after the loss of information. They have been picking Hawking's fault, but they can't pick them out. Therefore, they should not be lost through the sideline evidence and other methods to demonstrate the information should not be lost.

Regardless of how to make the information not lost, they first assumed that Hawking radiation can be modified. After being modified, the complicated quantum process near the black hole can be brought out through Hawking radiation.

Although I don't know how this process is done, quantum information scientists tell us that if you want to effectively extract the information, then the particles radiated between these Hawking must be connected by the method of quantum entanglement.

Quantum entanglement can be understood like this, put two particles together, and then put one on the other side, but still have a mysterious effect to contact them. If I measure one of the particles, the state of the other particle will change immediately. "Immediate" means no time, which is obviously super light.

But in this way, Einstein was unwilling. Because Einstein believes that the fastest speed in the universe is the speed of light. How did you get the super light speed? Of course, it was discovered that this method could not be used to convey information, so the contradiction between the general theory of relativity and quantum mechanics did not become so sharp.

Later, people verified quantum entanglement by using experiments to prove Bell's inequality methods. Of course, in fact, Bell's irresponsibility has loopholes to drill.

Back to Hawking radiation. If the Hawking radiation is entangled, we can extract information. The reason why Hawking radiation is actually at the cost of sacrificing partners to the black hole. Therefore, the particles running out of radiation have actually been entangled with the particles that fall in. If it wants to be entangled between the request required by quantum information scientists and other particles that run out, it is necessary to first and the particles inside the particles inside Broken diplomatic relations. A lot of energy will be released during the intercourse with the particles inside, which will generate a firewall.

Some quantum mechanics experts believe that the result of disconnection is to form a area full of high -energy particles -fire walls near the incident field.

In this way, COOPER is not like the classic physicist said, and will feel the threat of death through the incident, and he does not know that he is facing the threat of death. Instead, Cooper will be burned by the fire wall and even directly burned into slag.

If this statement is correct, there will be another group of people who cannot accept it, that is, scholars who study the general theory of relativity. They believe that this statement is completely logical and directly violates the equivalent principle of Einstein's general theory of relativity -eliminating the physical laws that people who feel free to fall into the black hole should be with the empty downs. People are the same.

And determining the location of the event field needs to predict the future. The photon himself does not know if he is in the field of incident. If you want to put the fire wall around the incident, do you want the firewall to predict the future?

If so, the entire physics is rewritten. If the firewall can be put in a little bit in the incident, it can actually come out. We did not see the fire wall in the photo. Of course, it can be said that the fire wall was formed in the late black hole, but some people said that it should be formed in the early stage. In short, no one can really confirm it.

Many people think that since there are so many changes, it is better to admit information loss and change the theory of quantum mechanics. Don't always try to change the theory.Especially Like Roger Peirus, he believes that the loss of black hole information is a critical part of the cycle universe model he proposed.All in all, in addition to the observation is very interesting and can bring us wonderful photos, it is actually very suitable for thinking tests, which can promote scientific development out of thin air.

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