The Black Hole

What is Black Hole?

1. Black holes are the dark remnants of collapsed stars, regions of space cut off from the rest of the universe.
2. Black hole is a place in universe having gravitational acceleration as strong as it pulls everything towards it. Even light cannot get out of it.

Black Hole Formation

• Stars shine because of the nuclear fusion reactions taking place in their cores.
• But when a star’s fuel supply is exhausted and the outward pressure stops, gravity causes the star to shrink which forms an ultra-dense object known as a Neutron star, also called Black hole.

Features and Structure of Black Hole

1. The defining feature of the black hole is other presence of Event Horizon.
   • Event horizon is a boundary in spacetime through which matter and light can only pass inward towards the mass of the black hole. Nothing, not even light, can escape from inside the event horizon.
     • The Event Horizon of a black hole is the boundary around the mouth of the black hole.
     • It represents the region where the escape velocity is exactly equal to the speed of light.
2. Matter inside black hole is so compressed that it forms a point of infinite density known as a Singularity.
   • The single point in space-time where the mass of the black hole is concentrated.
   • Region where the spacetime curvature becomes infinite.
3. A black hole can be thought of as empty space, with its mass concentrated at an infinitesimal point in the center.

Discoveries by Scientists

• Albert Einstein first predicted the existence of black holes in 1916, with his general theory of relativity.
• The term “black hole” was coined many years later in 1967 by American astronomer John Wheeler.
•  In 2019 the Event Horizon Telescope (EHT) collaboration released the first image ever recorded of a black hole.
  • On 10 April 2019 an image was released of a black hole, which is seen in magnified fashion because the light paths near the event horizon are highly bent.
  • The EHT saw the black hole in the center of galaxy M87.
• There are three types of black holes: Stellar black holes, Supermassive black holes and Intermediate black holes.

Weird Facts about Black Hole

• If you fell into Black hole , gravity would stretch you until your death.But a 2012 study published in the journal Nature suggested that quantum effects would cause the event horizon to act much like a wall of fire, which would instantly burn you to death.
• If a star passes too close to a black hole, the star can be torn apart.
• In Milky way galaxy there are about 10 million to 1 billion stellar black holes, with masses roughly three times that of the sun.
• Scientists can’t directly observe black holes with telescopes that detect x-rays, light, or other forms of electromagnetic radiation. But can detect the presence of black holes and study them by detecting their effect on other matter nearby.
• In every single second 10 stars explodes and forming Black hole or Neutron Star.
• If you are inside a black hole you would be able to see the back of your own head and the entire universe in a small patch of the sky.