The stuff of legends

A star has a life cycle, much like a product, but people like physics more than commerce. It starts as a nebula and then grows bigger and eventually turns into a star like our sun but usually bigger. After the halfway point, the star has used up the hydrogen in its core and cannot continue fusion of it so it reverts to the residual helium. This new fusion causes the core to contract and the star fuses three helium nuclei to form a carbon atom. This extra energy released during fusion causes the star to increase its size drastically to form a red giant. Then the usual stages of a star form like a black dwarf and a white dwarf. Once a star has used up all the energy in its core it turns into a neutron star, which is unbelievably dense. Finally, due to its immense density, the star warps spacetime so much that it turns into a black hole(general relativity). A black hole has such a strong gravitational field that even light cannot escape from its outer boundary called the event horizon, also called the "point of no return". A black hole distends space and also time as if an object were to be sucked into it, it would appear to freeze just before the mouth of the black hole. The black hole appears to have stopped time or really really slowed it down which is the same effect for a person travelling at close to the speed of light when he sees other bodies frozen around him. Both the above situations are hypothetical. The central point of a black hole is called a singularity, a point of theoretically infinite pressure. It is a point beyond which nobody knows what lies. The space surrounding a black hole is called the ergo sphere. You would think that a black hole would be invisible and that how scientists have indeed found such dead stars in the world. Black holes emit large amounts of electromagnetic waves called 'Hawking radiation'. This process is also the process by which black holes evaporate or dissipate into nothingness, or they would continuously suck and live. Scientists track this emission and predict the location of black holes by the disturbances their gravitational fields cause in the fabric of space. A cool application of black holes is using them as time machines. Floating in space just outside the event horizon of a black hole would result in time nearly standing still for you while time would flow at the normal rate for everything else. You would then travel into the future. Nice way to check your exam performance and then see if it would be worthwhile to study.

   

Several supermassive black holes exist with mass equal to the mass of several billion suns. We have a supermassive black hole at the centre of the milky way. Theoretically, every object can become a black hole if compressed to its Schwarzchild radius. Every object has one.