BLACK HOLES.

• INTRODUCTION AND DEFINITION OF BLACKHOLE. 

Blackhole is based on the theory of general relativity which was given by Einstein. Black holes are a hollow space having an immense gravitational pull that even light cannot pass through it and thus remains a mystery to the entire mankind even after a century of its discovery. The term was coined by John Wheeler a quantum physicist in 1783.

• DEFINITION OF BLACK HOLE. 

It is a hole that doom every passenger passing by. The concept can be easily understood by knowing what escape velocity is. Formally, escape velocity is the speed an object must attain to break free of the gravitational attraction of another body.

• CONCEPT OF BLACK HOLE. 

Blackhole can be understood by several methods one of which  is the concept of escape velocity(as mentioned above), and the second is the black hole string theory, fuzzball theory replaces the singularity at the heart of the black hole by posting that the entire region within the black hole's event horizon is actually a ball of strings, which are advances as the ultimate building blocks of matter and energy. Blackhole are big holes in space-time. They have a surface that is called a horizon, which marks a point of no return. 

• WHAT HAPPENS WHEN A PASSENGER IS NEAR A BLACK HOLE.

A person who crosses the horizon, it will never be able to come back out. However, he will not feel anything special when he crosses the horizon. Only a while later will he feel very uncomfortable when he is crushed into the singularity, a region with very high gravitational fields. Fortunately, if you stay outside the horizon, nothing bad happens to you. The singularity remains hidden behind the horizon.  

• STRUCTURE OF BLACK HOLE. 

The black hole is a black coloured empty area within which the force of gravity is so strong that nothing, not even light can escape. The basic structure of a black hole consists of a singularity hidden by an event horizon. Its is composed of a one-dimensional string of energy that takes on its identity by vibrating in different modes and/or frequencies. The black hole is an extremely dense object. The size is very less with respect to their mass. The string that surrounds the hole emits lights which is the only medium to detect black hole and study it well. 

• BLACK HOLE IN MODERN ERA. 

Blackhole studies are super important because black holes have the power to create, sustain and destroy anything in the universe. Create and destroy just means transform. They are observed to be the most massive, powerful and luminous 'objects' in the entire universe. If they weren't so gravitationally powerful and if they allowed lights to escape constantly, they'd always look like brightest stars in the universe and its perhaps the strangest yet fascinating object known to us.