Friday, August 20, 2010

Will black holes eventually eat the universe?

Roberto Fernandez

First let us understand how black holes come to be. The black holes form from dying stars which after a natural process, begin to accumulate an enormous concentration of mass in a minimum radius so that the escape velocity of this star is greater than the speed of light. What is escape velocity? Well imagine a friend of your throws a ball up in the air with a certain force and speed. Eventually the ball will come down, but imagine this: Your friend throw the ball with such strength and speed that the ball never comes down. Very impressive right? The velocity needed to achieve such a task is called the escape velocity. When the escape velocity become so great, because of the increased mass of the star in such a small radius, the former star does not allow anything to escape its gravitational field, even light cannot escape it.
 
The answer to our main question is not quite simple, and you will understand why. We defined a black hole, well Stephen Hawking did with Roger Penrose 40 years ago, as the event horizon which every object is inevitably absorbed into the center of the singularity. Well, what do we mean by event horizon? Remember the Schwarzschild radius? Well, if you do not  remember, it was the radius from which a black hole swallows every object inevitably, said radius defines the event horizon, then the radius in known black holes are not the size of the universe (actually , no one knows for sure the size of the universe but we have a vague idea).

This means that black holes can swallow nearby bodies but not absorb all the objects in the universe. Unless a significant percentage of matter in the universe are becoming black holes ...but that is unlikely.

The effect is similar to that of normal gravity, it has a scope which cannot greatly alter the other objects, for example, the terrestrial gravitational pull affects only the bodies that pass near it (the Moon and some planets) but not affect the stars in the entire Milky Way or less, from another galaxy.

On this subject there has been much speculation, there have been a number of theories, some wild and some not so wild, it is said that black holes are the gateway to heaven, while others argue that black holes might be a kind of teleport matter (this thought was initially presented more than 25 years in the series "Star Trek") but they all are nothing but baseless guesses without an rational basis. The only certainty is that, speaking backed by science, a black hole has a limit in its action range, so relax, of what we know, the universe will continue its unstoppable march.

Important: It is necessary to emphasize that only a few months ago American scientists were able to demonstrate that the speed of light is not maximized but with a quantum tunneling photons able to mobilize an equal and greater speed. While this result calls into question certain parameters considered by relativity does not disqualify it entirely….yet.

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