Black holes are some highly concentrated mass where gravity rules upon radiation and as far as we know, there is no way to escape from it; not even light can escape a black hole. Despite that, Sir Stephen Hawking has declared recently that this fact should not be considered entirely true. At least at some point, some information can be recovered.

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                                                     Figure 01 – Black hole, artistic work (Source: deviantart.com)

Black holes are invisible and have nothing to do with holes. They are enormous packages of mass squeezed into a tiny space. Black holes dimensions vary widely. Some of them are as big as an atom. Some others are bigger than a million suns. To better understand the concentration of mass into a black hole, imagine it like a grain of sand that weights as much as Earth. Black holes are usually created when a star is dying. Let’s take our sun as an example. Our star has a certain gravity pull. Sun’s gravity pulls Earth and other planets towards it, forcing them to move in circles. On the other hand, our sun radiates energy using photons of light. Light warms our planet and makes life possible. Our sun age is relatively young and its activity is far from the danger of transformation into a black hole. Sun’s gravity and radiation equilibrate each other, so everything is fine. Sun radiates energy because of the nucleic reaction of fusing two atoms of hydrogen into creating an atom of helium. At stars that have a much bigger mass than our sun, helium gets fused into carbon; carbon creates neon, then oxygen is created, then silicon and at last iron. Iron does not radiate anymore. This means that the star does not radiate and the delicate balance between radiation and gravity is over. The star begins to pull more and more mass, until it collapses into itself, creating a black hole.

There is a paradox about black holes called “the information paradox”. Universe, as we know, it is a place where information gets stored eternally, at a fragment of time and space. It can not be destroyed, nor lost. Black holes seem to violate the law. For many years it is believed that information inside a black hole is entirely lost forever and can not be recovered. How to understand that? Let’s imagine a paper where some information is written. When we burn the paper, it turns into ashes. Despite that, ashes contain the information that a paper has been burnt. If we use an advanced technology we can recover the information that was written on the paper. On the other hand, if we drop the paper inside a black hole, it can no longer be known if there was a paper dropped, or a car, or an atomic bomb. It means that everything that falls into a black hole loses its past history, its identity. 

All that was considered true, until some days ago, Hawking presented a new idea on how information could escape black holes. It has been proved scientifically that black holes radiate. They evaporate very slowly until they get destroyed. The radiation of black holes is called Hawking radiation. Losing energy means that black holes get smaller until they explode. When a black hole explodes, Hawking thinks that it would release all the traces of the information that has sucked during its life. Considering that, it could be said that information is not entirely lost, but on the other side, as Hawking states, it can no longer be used for practical purposes. So, even if we happen to fall into a black hole; even if we die, some traces that prove our existence can be released when the black hole explodes.

In fact, there is something else to be aware about black holes radiation. They radiate very slowly. It means that when the first black hole will radiate enough to explode, universe probably will no longer exist. Does it mean that black holes can create another universe, using the information collected from a previous one? Is it possible that Big Bang was an explosion of a huge black hole? Where it begins and where it ends this chain of explosions? How much do we know about our universe? All we know is that we know nothing; yet. 

  

REFERENCES

https://www.youtube.com/watch?v=DkRDmJpthXg

http://qz.com/487418/stephen-hawking-explains-how-to-escape-a-black-hole/

http://www.nytimes.com/2016/06/07/science/stephen-hawking-black-holes.html?_r=0

http://www.nasa.gov/audience/forstudents/k-4/stories/nasa-knows/what-is-a-black-hole-k4.html

http://spaceplace.nasa.gov/black-hole-rescue/en/