Black Holes- Wonders of Universe

Exploring the black holes

What is a Black Hole?

• A black is a mysterious place in the cosmos where laws of physics do not work.
• It is a type of place where even light cannot escape due to a very strong gravitational pull.
• Its existence took place when the core of a supermassive star collapse after which a supernova explosion took place.

FORMATION OF A BLACK HOLE

• To understand the formation of a black hole we need to understand the concept of a star.

• Nuclear fusion is the process through which a star produces its energy.

• A star is made up of mostly hydrogen and helium.

• In its core, nuclear fusion occurs in which hydrogen combines with hydrogen to produce helium. This process continues further and forms more heavy elements like carbon, silicon, magnesium, deuterium, etc.

• Iron is also formed in the core which can be referred to as the murderer of the star. The problem with iron is that it does not further react to form elements.

• As a result when the amount of iron element increases the process of nuclear fusion decreases and after some time it completely stops.

• Due to this, the balance between the radiation and gravitational energy which keeps a star stable comes to an end making the core of the star to collapse giving a supernova explosion after which a black hole is formed.

• It happens with only supermassive stars.

• A supermassive star can also become a neutron star after its death. We will study it in further parts.

The above picture gives a brief explanation about the lifecycle of a star. After its death it can become :

• White Dwarf
• Neutron Star
• Black Hole

Structure Of a Blackhole

A Blackhole is composed of the following parts

1. Accretion Disk
2. Ergosphere
3. Static Limit
4. Event Horizon
5. Singularity
6. Photon Sphere

• .Accretion disk – It is rotating disk on the outermost side of the black hole where celestial objects, planets, stars and other objects which got trapped in the gravitational force of the black hole rotates around it. It is like a ring of the black hole.
• .Event Horizon – It is the opening part of the black hole. Here the gravitational pull is the least and it is a point of ‘no return’ from this point even light cannot escape. This part is very fluctuating and forms virtual particles.
• .Singularity – It is the center of the black hole. Here, the density is infinite and gravitational pull is the strongest. According to theories singularity is a link between a black hole and a white hole.
• Ergosphere – It is a layer around the black hole from where the gravitational force of the black hole starts influencing objects towards it.
• Static limit – It is the outermost surface of the ergosphere.
• Photon Sphere – It is a spherical area around the black hole where the gravity is so strong that it forces the photon particles(Light) to rotate around it. It appears like a bright ring around the black hole.

Major Breakthrough in the study of a black hole

On 10 April 2019 a direct image of a black hole was captured. The Picture shown above is the image of a black hole in the Messier-87 Galaxy captured by collaborating many telescopes together from different places. This telescope was named as ‘Event Horizon’.

Death of a Black Hole

Do black holes die? Life and death of the most powerful forces in the Universe ...After all these pieces of information, the only question remaining is how does a black hole dies. To understand this we need to understand the concept of Stephen Hawking’s Theory ‘Hawking Radiation’.

According to this theory the area around the event horizon is very fluctuating due to which virtual particles form there. virtual means particle and antiparticle when these particles meet each other then they cancel out each other. But there is a different story in the event horizon as these particles are unable to meet due to the gravity of the black hole. 

So the anti particle also called negative particle falls down in the black hole and the positive particle remains on the event horizon and gets seen as radiation around the black hole. As these particles cannot meet each other so they cannot cancel out each other. 

The negative particle which falls into the black hole weakens it and slowly due to this process the black hole evaporates and gets disappear after many years. This process takes place very so the black take a very long time to disappear.

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