BLACK HOLE: A HUNGRY MONSTER

The most important headline in the news is the discovery of a black hole at the centre of the Milky Way Galaxy...

The idea behind black holes can be conceived both theologically and scientifically. The development of science and technology has helped us to know more about these gentle giants, wait, are they gentle???

Many people, especially the young consider black holes as monstrous systems which engulfs everything which comes near its field of influence, according to them black holes are horrific and terrible. The truth is not far away from this, but do you know that black holes are very essential in our Universe. Everything in our Universe has a positive and negative aspect associated with it.

NASA's modern telescopes captured the image of this black hole situated in the centre of the Milky Way Galaxy...you can find the image below...

                                            

Figure 1: Sagittarius A*

''In space no one can hear you scream; and in a black hole no one can see you disappear''

With this insightful quote by Professor Stephen Hawking, today, let us discuss about black holes, in particular about Sagittarius A*, Milky Way's own Black Hole!

HOW ARE BLACK HOLES FORMED?

We all know about stars. They are those twinkling objects that you see in the night sky. The stars live for many years. Different stars have different life span; the life span of a star is determined by its size , say for example, our Sun, it is a star that can live for about 10 million years...this means our Sun will burst or die in about...🤔...7 million years...

Black holes are formed from such dying stars...now can black holes be formed from every star???

Black holes are formed when the centre of 'massive' stars collapse or bursts. The stars burst in a supernova explosion. A supernova explosion is very powerful explosion, the resulting light is so bright that it can be seen across the universe.

As already mentioned the supernova explosion is very powerful that most of the stellar material gets blown away and what remains then is the black hole. You may also note the point that supernovas occur rarely...

                

Figure 2: The bright white spot that you see in this picture is a real supernova explosion

HOW IS A BLACK HOLE?

''What happens in a black hole, stays in a black hole''

Black hole has an extreme concentration of mass (or matter), due to which gravity is exceptionally strong there. As a result of this strong gravitational field, no matter, even light, cannot escape from the clutches of a black hole.

The smallest black hole in the Universe itself is three times the mass of the Sun, that is about 5.9673×10³⁴ kg...

Sagittarius A*, the black hole present at the centre of the Milky Way Galaxy, is about 4 million times the mass of our Sun...😵😳😲, this means its mass is about, 7.9564×10⁴⁴kg...and therefore according to Newton's Universal Law of Gravitation, greater the mass stronger will be the gravitational force...you can't even imagine the gravitational field that this black hole has...

All the concepts of space and time that you learn in school, which hold good in other parts of the universe, breaks down inside/ in the vicinity of a black hole...

                                                        

Figure 3: Albert Einstein

According to Einstein's Theory of General Relativity, nothing can escape from a black hole. The Theory of Relativity is one among the few theories which can explain most of the macroscopic phenomena and is used widely in understanding more about black holes...

BLACK HOLES AND TIME

Black holes have an amazing relationship with time...do you know???

Time ticks slowly near a black hole. This is due to the strong gravitational field of a black hole with which it can curve spacetime in a way that it affects the measurements of time and space near a black hole...

With the concept mentioned above we can easily answer the phenomenon of ageing. A person will age slower near a black hole than at a location far away from it...you can even become 'immortal' if you are successful in getting into the black hole, which is scientifically inconceivable. 

HOW BLACK HOLES DIE OUT?

Black holes are living systems, they become bigger and bigger by engulfing matter which gets trapped in its strong gravitational field. 

                                                              

 Figure 4: Stephen Hawking

The seminal contributions of Professor Stephen Hawking played a major role in understanding the black holes better. It was Stephen Hawking who said that black holes doesn't last for long. Why???

This is due to Hawking radiation...

Hawking radiations are nothing but electromagnetic radiations emitted by a black holes. When black holes emit Hawking radiations the mass of the black hole reduces along with its rotational energy this in turn results in a theoretical phenomena known as 'black hole evaporation'

WHAT HAPPENS WHEN TWO BLACK HOLES COLLIDE?

                                                           

Figure 5: Binary black holes

When a black holes gets caught in the gravitational field of another black hole near to it, they are prevented from escaping from each others gravitational fields. This in turn results in the formation of huge, new black hole which has a humongous gravitational field due to which it will always be violent and extremely active...

Such a system of two black holes orbiting close to each other are called binary black holes.

The following set of images shows the different stages involved in the collision between two black holes...

                                                               

(1)

                                                    

(2)

                                                   

(3)

 

                                                   

(4)

                                                  

(5)

                                                    
Figure 6: Series of images (1) to (5) depicting the collision of two black holes

Albert Einstein once said,

''Black holes are where God divided by zero''

This is the best description of a black hole. This quote by history's greatest scientist underlines the uniqueness, extremity and vagueness of these ultimate giants...

References:

1. All the images given in this blog were taken directly from Wikimedia Commons.

2. The information regarding some values and some concepts were taken from websites, mainly from jpl.nasa.gov