The idea of a Gravity (Gurutvakarshan) and Black Hole is very fascinating among the students and common people also. Black holes are strange and fascinating star-like objects found in space. Different kinds of myth associated with Black Hole. Some people think that Black holes are the giant dead star which can attract each and every system around it, but it is not true. The name Black Hole is given by the Wheeler in 1970s. The idea of a black hole was firstly introduced by Laplace in the 19th century. The behind is that Black holes are such types of object that nothing can escape from the surface of the black hole. Gravity (Gurutvakarshan) and Black Hole are so huge.
Let us talk what is the criteria to escape from the surface of any star or any massive object. Assume any massive isolated object situated in the universe. Mass of the object is M. Radius is R. If R is smaller than this value than escape speed will be greater than c which is not possible. It is known as the radius of the black hole. Very heavy massive stars 10 times of the sun becomes unstable and convert into this type of object which is known as a black hole.
The vast majority of people have no idea how their lives fit into the story of the universe. Most people don’t know what
they are. They eat pizza and watch the video without understanding that they are part of a universe in which galaxy collision trigger Black Holes. Black holes are not randomly wandering in the universe or randomly swallowing worlds.
They follow the laws of gravity just like other stars in the universe. There is a myth about black holes that BH irresistibly suck things in. That is a common misconception in science fiction. In fact, a spherical black hole of mass M attracts exterior mass no more strongly than a star of mass M. Gravity (Gurutvakarshan) and Black Hole is an object of extreme mass density. If Sun somehow replaced tomorrow by a spherical black hole of the same mass, our climate would be significantly modified, but the orbit of the earth would be almost unchanged. But Due to strong gravitational attraction in the space region of BH, even light cannot escape from their grasp if it enters inside BH. Black holes are massive but cover only a small region of space. They have an extremely powerful gravitational field. The strong gravity occurs because the matter has been occupied into a tiny volume. It happens at the end of a star’s life. Some black holes are a result of dying stars. Because no light can escape, black holes are invisible. Numerous of massive black holes may exist within the Milky Way galaxy. The largest black holes are called “supermassive.” These black holes have masses greater than 1 million suns combined and would fit inside a ball with a diameter of about the size of the solar system.
Astronomical evidence suggests that every large galaxy contains a supermassive black hole at its centre. Firstly The French Scholar Laplace speculated about the existence of an object so compact that the escape speed would be greater than the speed of light. The first relativistic calculation was performed by Karl Swartzchild (1916). Albert Einstein predicted black holes in 1916 with his general theory of relativity. The term “black hole” was coined in 1967 by American Astronomer John Wheeler and the first one was discovered in 1971. Black holes have two things, the singularity and event horizon. The event horizon of a black hole is the boundary around the black hole singularity where light loses its ability to escape. Once a particle crosses the event horizon and enters inside BH, it cannot leave. Near to the event horizon, gravitational force remains constant. The inner region of a black hole, where its mass lies, is known as its singularity, the single point in space-time where the mass of the black hole is concentrated. Virtually nothing can escape from them.
