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Generally, it is understood that the light always goes to the straight. Why? Because the light is choose the shortest way to go from one place to the next. The straight line is the shortest way between two points In a plain surface.We knew that the space-time was flat before the relativity was released, so we saw the light going straight on the straight line.

When light goes from one medium to another, Then refraction will occured. Refraction of light means changing the direction of light.As the light goes from the medium to a thick glass wall, its direction will changes. Like the image below.


It was said in the previous era that the light bends. But during the reflection, the path of light is not left at all. Just change the direction and move straight to the direction. Then the angle of light was created with the previous path. It is not called curve in the way of light.

Until the discovery of Einstein's general relativity, everyone knew and vowed, the light went straight on. But Einstein showed that the light was bends when he passed by the heavy object. That is, the gravitational force of the heavy object bends to light.

So what does that mean?

The light choose the shortest path when it was gone. But when an object passes through the gravity field, the light is bends. Then the narrow path of light in the gravitational field must be the shortest path, of course the shortest way. Then we can say that, the short path of the two points between in the gravitational field is also bend . From here on, Einstein thought that the gravitational field is not a flat field. Rather than Bend it.

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So we can say that, our universe is spreading into many planets stars. There is a gravitational field for everyone. If all the gravitational fields are bent, then the huge space in the universe will also be bent due to the gravitational field of this planet. Speaking in a simple language would be bogged down. However, it would be wrong to say that only the space of the great space is wrong. In fact it is a coordinated form of space.

Let's get this chickenpox over and over again. Suppose, a huge sheet floating in the vacuum. That is the period of our universe. Let's say the sheets are straight like the plane surface. Now a heavy object is placed on the sheets. The cloth will be distorted. The thickness of the material will be increased as well as the curvature of the sheets. Let's say a worm was hanging on the sheet. As long as the sheets were straight, the path of the insect was straightforward. But after heavy material, the sheets were distorted. The path of the insect is not straightforward. Bent over.

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Now if another heavy object is left close to the previous object, the object will want to roll over it with the twisted path of the sheet and fall it on the previous object. Looking from outside, it seems that the previous heavy object wants to attract the next item to itself. Now, when the sheet is replaced by the space of the earth, it can be seen that the planets and stars are attracting each other for the same reason. Newton said the matter was gravitational force.

Let's talk about our world. The mass of the Earth curves the space-time. As a result, a gravitational field has been created around it. The moon is rotating on the curve. We are going back to the earth, no object is falling from the earth, it is not falling into the universe, because of the reason that the space is curved here by the earth. The space was stuck in black hole. We are stuck on the earth, for the same reason.

The earth has bumped space time. Because of the space curvature the moon is rotating around the earth.

But Einstein said, this is not a attraction force, it is happening because of the curvature of space time. That is, the curve geometry is a factor in space. It does not just move the object in a crooked way, it also binds the path of light.

But Einstein did not say anything about the object. He said that the space-time was curved due to the power of strength. That is, the level of curvature of space-time depends on the amount of power. Here was the failure of Riemann. He simply said natural forces were created due to the curvature of the geometry of the universe. But how did the geometry of the universe bind, which he did not know the answer? In fact, Riemann did not know what relation between the power and space time.


Using the geometry of Riemann,Einstein established the field theory for Faraday's magnetic field, like the theory of electromagnetism, also set. Then in 1916, Einstein established the new theory of gravitation. In this theory, the theory of gravitation was combined with the theory of gravitation. This theory is named as General Theory of Relativity or General Relativity.

Newton thought light is a particles. Therefore, the gravitational force had its effect on the particles of light in his gravitational regimen. Einstein's gravitational style different from others. Moreover, Einstein confirmed the constantity of the velocity of light. It was shown that the direction of light is curved due to space-time. Further, the frequency of light is affected by the gravitational field while passing through the strong gravitational field.

Einstein said that the frequency of the light wave depends on the gravitational field. The gravitational field is as strong as the frequency of light decreases. Where the gravitational field is less powerful, the frequency of light is relatively high.


Suppose an atom is a light source. If the atom is in the earth, then let it take a stroke closer to the frequency of the violet light. But if the atom is on the surface of the sun, its frequency will be much lower than the frequency of the violet light. That is, the frequency will be near the red light.

It is good to say, the sun's white light is in seven rainy days. The mixture of colors. Purple, blue, asparagus, green yellow, orange, red One of them is called BeniAasunkala. This combination of BeniAasunkala is not random. Sorted by frequency and wavelength sequence. The frequency of such violet light is the highest.

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Lower than the blue light. The next place is in sky, then green, yellow, orange and finally red. We will work with the waves of blue and red light here. Because the spectrum of the violet light is not so obvious. The blue light spectrum is much more clear than that. So many advantages of working with blue light.


Now one thing is important to know, the more the frequency of light is the less wavelength of that light. As the violet light wavelength is the smallest. What is the frequency and the wavelength? We already know that the light continues to wave. The wave of light is like the image below.



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Each wave has a top and bottom point. Fill a half-cycle of wave from one peak point to another top point. That means 180 degree passes. When two semi-circular steps are completed, the light passes through a full cycle. The light that completes the whole cycle in a second is called a frequency.

The straight line is also wavelength from one point of the wave to the other end point. Distance from a point t to another point is also the wavelength.

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A full circle of blue light is quite long. So one wave from the top to the other is the linear length of the wave top. On the other hand, the distance between top to second point in case of red light waves is much higher than blue light. The red light wavelength is more than just the light of light, more than any visible light. Looking at the picture below, you can understand. The picture shows the waves of blue, green and red lights.

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Now, in the light of blue and red, we take two marginal waves of Beni Sahakalara. Purple has been omitted, why has it been explained earlier. So both of us can catch our optical light. Now we'll go to Doppler Effect. We can use the train station in the example of Doppler effect. But here the sound wave will be used instead of light waves.

Suppose you are sitting at the station. A train is coming from the distance to the station to play the whistle. You hear, the train's whistle's words are sharper with the time running. Once upon a train stand on the station. Suppose, the train played whistle at the station. Then you will not hear the words of whistle as sharp as before. You will hear the usual whistle.

Train passengers like to hear that. When leaving the train station, the sharpness of the words of the train whistle will be reduced. The whistle will also be very thick. Passengers on the train always hear the same sound. Why is that? This is due to the Doppler effect. Austrian physicist Christian Doppler first discussed 1842 Doppler effect.


This change in the frequency of words due to relative speed. Einstein calculated that there was a difference in the frequency of the photographic wave while passing through the gravitational field. Doppler effect also works for the light. When the source of light is near, the frequency of light is sharp and the distraction of the frequency becomes blue.


When the source moves away, the frequency of light drifted towards the red. Einstein noted, where there is no gravitational field, the frequency of light is somehow where there is strong gravitational field where the frequency of light is less than before. That is, the frequency of light in the gravitational field is less than the void and the wavelength increases.

Now what is the maximum wavelength and how much can be reduced? Since the red light wavelength is the highest, it has a boundary. Again the blue light wave length is the lowest. So this is another boundary.

Now the point is that the gravitational field is as strong as that the gravitational split, where the wavelength of the light is the greater light goes towards red. Just as the green light position is in the middle of the seven light.

Suppose, a green light is taken in a strong case of gravity. As a result, let the green wavelength of the green light be equal to yellow light. Nevertheless, we will call it red-minded. Look at the picture below:

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Here the green light wavelength has become more equal to the yellow. But we assume red light is the destination point. So going towards the yellow of the wavelength means that deviation is going towards red.


Now the light is taken away from the strong gravitational field, and the relatively less powerful gravitational field is taken. As a result, the frequency of light grow up. Wavelength of the green light is decreased and transmitted into sky.
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(To be continue...)

Thank you for taking the time to read this post. Your COMMENTS and UPVOTES are highly appreciated.

Check other parts of this Series here:

1. Black Hole; Part-1 : History Seen Back

2. Black Hole; Part-2 : Gravity Background

3. Black Hole; Part-3 : Newton's Gravitation

4. Black Hole; Part-4 : Newton's cannon and earth's escape-velocity

5. Black Hole; Part-5: Light burning

Black Hole; Part-6 : Relativity and Modern Gravitation

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