# I Need the explaination of The image of formation of black hole

• Huma waseem
In summary: The Schwarzschild radius is the radius at which all the mass of the object becomes concentrated at the center of the black hole.The significance of the event horizon is that it is the boundary of the black hole universe. If you cross the event horizon then you have crossed the boundary of the black hole and you are no longer in the black hole universe.

#### Huma waseem

I Need the explanation of "The image of formation of black hole"

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• pic1.doc
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How about you explain it to us first. What can you tell us about this diagram? What do the x and y axes represent? What is the significance of the event horizon?

Sir that is my basic problem.I ve got this image and now i am unable to understand it,Event horizin is considered as the radius of the black hole this is the point i got from the wekipedia site and in this image it is quite difficult to understand where is the collapsing star from where it is looking like the symmetric collapse?and the most confusing thing present here is the representation of the singularity as a wave form... the co ordinates also hav nt shown here, Can u help me find out its complete discription?

It maybe the case that the singularity is not visible to a far-away observer because light is not able to escape the collapsing star. This is essentially what we mean when we say that a black-hole has formed. The singularity is hidden from view by the event horizon, which is the boundary of that spacetime region surrounding the singularity which cannot communicate with the far-away observer.
do anyone help me to discribe it by the above attached picture?

Last edited:
helloooooooooooo

I'll try moving this thread to the General Relativity forum. I think you'll need a specialist to help with your question.

Huma waseem said:
Sir that is my basic problem.I ve got this image and now i am unable to understand it,Event horizin is considered as the radius of the black hole this is the point i got from the wekipedia site and in this image it is quite difficult to understand where is the collapsing star from where it is looking like the symmetric collapse?and the most confusing thing present here is the representation of the singularity as a wave form... the co ordinates also hav nt shown here, Can u help me find out its complete discription?
The vertical dimension represents time, the horizontal dimension space. If you take a horizontal cross-section of the diagram it shows the position of the surface of the star and of the event horizon at a given time--you can see that the radius of the star steadily shrinks and the radius of the event horizon grows from the point in space and time labeled "O", until the event horizon reaches a fixed radius at the moment the collapsing star is fully inside it. The representation of the singularity as a wavy line is just a visual convention, don't take it literally.

Yes, it's a standard space-time diagram, which puts time on the vertical axis. (I'm not quite sure where this convention came from).

The horizontal axis represents the radial spatial coordinate using a spherical coordinate system (r, theta, phi). To fit the diagram on a 2d page, theta and phi are omitted (the problem is symmetrical in theta and phi anyway).

The vertical lines are drawn at the instant the body collapses to form a black hole. They represent light cones at that point. They illustrate that the path of light has a constant spatial coordinate, hence the light is "trapped" by the gravity / geometry of the black hole when a certain point in the collapse process is reached.

Until the object collapses sufficiently, the light is not trapped. The event horizon forms and the light is trapped only when the object is contained within its Schwarzschild radius.

## 1. How is a black hole formed?

A black hole is formed when a massive star dies and its core collapses due to its own gravity. As the core collapses, it becomes infinitely dense, creating a singularity, which is the center of the black hole. The gravitational pull of the singularity is so strong that even light cannot escape, making it appear as a black hole.

## 2. What happens to matter that enters a black hole?

Any matter that enters a black hole is pulled towards the singularity, where it becomes infinitely dense. This process is known as spaghettification, where the object is stretched and torn apart due to the intense gravitational forces. Once it crosses the event horizon (the point of no return), it is impossible for anything, including light, to escape the black hole.

## 3. Can black holes be seen?

No, black holes cannot be seen directly as they do not emit any light. However, we can observe the effects of black holes on their surroundings, such as the distortion of light and the movement of matter around them. These observations can help us identify the presence of a black hole.

## 4. How do we know black holes exist if we can't see them?

Scientists have observed the effects of black holes on their surroundings, such as the gravitational lensing of light and the movement of stars around a central point. Additionally, the gravitational waves detected by the LIGO experiment in 2015 provided further evidence for the existence of black holes.

## 5. Can anything escape from a black hole?

No, nothing can escape from a black hole once it crosses the event horizon. This is because the gravitational pull of the singularity is so strong that even light cannot escape, making it impossible for any form of matter or energy to escape as well.

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