Post No. 2: Black Holes.
Black holes is an exciting topic. They are the most important consequence of the Theory of Relativity even that Einstein never expressed enthusiasm. The general relativity predicted the presence of a mass deforms space-time in such a way that the paths taken by particles bend towards the mass. At the event horizon of a black hole, this deformation becomes so strong that there are no paths that lead away from the black hole.

There are many definitions of black hole as “black hole is a place in space where gravity pulls so much that even light can not get out. The gravity is so strong because matter has been squeezed into a tiny space. This can happen when a star is dying.” (NASA)

 The definition I found in Wikipedia says;” A black hole is a region of spacetime exhibiting such strong gravitational effects that nothing- not even particles and electromagnetic radiation such as light-can space from inside it.”

The first use of the term “black hole “ in print was by science journalist Ann Ewing in her article “ Black Holes in Space” dated 18 January 1964, which was a report on a meeting of the American  Association for the Advancement of Science held in Cleveland in Ohio.

The defining feature of a black hole is the appearance of an event horizon- 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.

 Stephen Hawking has compared crossing this boundary to going over Niagara Falls in a canoe: if you are above the falls, it is still possible to escape if your paddle hard enough. Once you tip over the edge, however, there is no going back. He has written many articles about this topic and we can watch many videos in Youtube and others.

The photo shows  a spiral galaxy called Messier 106. NASA/ESA Hubble Space Telescope. It is located over 20 million Light- years away. At his heart, as in most spiral galaxies, is a supermassive Black hole, but this one is particularly active.

There are many scientists that had been investigating and writing about this phenomenal topic but still are many concerns and is not easy to understand. 

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