Black Holes

People often ask if Moon revolves around Earth, Earth revolves around Sun, then what does the Sun revolve around? It has kept astrophysicists curious for decades. According to recent explorations, astrophysicists have concluded that our sun revolves around the center of our galaxy (Milky Way galaxy) where there is a super massive black hole

Black Holes are centers of high gravity where the gravitation

al force is so high that light also cannot escape its gravity. These are called black holes because it reflects nothing (a perfect black body in thermodynamics). For this reason, they are completely black and are not visible by telescopes. Black holes are formed when the

death of a star is by supernova leading to the formation of planetary nebulae & then if the mass of the remnant exceeds about 3-4 solar masses .In this case the collapse of the star continues to give

rise to a black hole.

FORMATION OF BLACK HOLES-

PROPERTIES-

At this condition, when there is infinite gravity, there are only 3 physical

properties-Mass,

Charge and Angular Momentum. At this case

,the matter is said to be stable.

However, Schwarzschild black holes, the simplest black holes, have only mass. Scientists believed that black holes are entirely black and emits

no radiation .However, in 1974; Stephen Hawking showed that black holes also emit small amounts of thermal radiations called Hawking radiations which describe evaporation of black holes. There are also rotating black holes known as Kerr black holes.

STRUCTURE-

The region of the black hole on reaching which nothing can escape is called the event horizon or the Schwarzschild radius.

Within this radius escape velocity equals the velocity of light. The black holes, on account of high gravity, deform the space time fabric to such an extent that a passage through this fabric is made. Such passage might take us to a different part of space and time. This enables time travel. In Schwarzschild

black holes, there is a photon boundary of radius 1.5 times Schwarzschild radius, called photon sphere. These black holes are non- rotating and charge less black holes.

So,scientists have come to a conclusion that these black holes can help us understand the theories of BIG BANG expansion ,time travel ,parallel universe etc.May be,in future, we can travel with them through space and time.

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