by Toni Gabucci

Created on: March 21, 2010

Black holes- Do they even exist?

Even though black holes have finally achieved acceptance in the public mind, there have still been questions regarding the existence and characteristics of black holes among the scientists.

The “Classical” concept of a black hole is a star that has collapsed to a size of 10^-33 of a centimeter- that's a point followed by 32 zeros and a one. Now, with such a phenomenally small size and the entire mass of a star, you can see that we are dealing with some extreme gravity here. The gravity around such an object- a “Singularity”- is so strong, that it is held to pull in everything around it, including light. Another important component of a black hole is the “Event Horizon”. This is the point of no return for anything falling into the black hole. Past the event horizon, nothing at all can escape.

This is what presents a problem.

According to quantum mechanics, information about systems is never lost. In theory, if you knew where every particle in the universe was and where it was moving right now, you could predict where everything is going to be at any moment in time, back the the creation of the universe and forward trillions of years in the future. The concept of the event horizon and the irretrievable information that is lost behind it puts a kink in this theory. Also troublesome is a situation called quantum entanglement. This is a puzzling part of quantum physics which deals with two particles that are connected in a way that makes them act like they are one item. You can put a trillion lightyears between the two particles, but if you do something to one of them, the other immediately feels the effects. But what happens if one particle of an entangled pair falls past the event horizon of a black hole? For it to be able to “tell” it's partner what happened to it, information must pass through the event horizon!

One of the ways that some scientists have tried to explain this loss of information is through hawking radiation- a way that virtual particles interact with the extreme gravity at the even horizon. However, this slow leaking of information doesn't solve the problem of the instantaneous data transmission of entangled particles.

An interesting new theory is one of “Black stars.”. This theory states that in the course of collapsing into a black hole, the hawking radiation removes enough of the star's mass that it's no longer big enough to become a singularity. The black star still has enough gravity that it sucks in light- thus still remaining unseen- but it doesn't do so completely. There is no event horizon in this circumstance, no point of no return, so there is no loss of information in the universe. However, there are still problems with this theory, particularly concerning the incredible speed at which a black hole typically forms. Would there be enough time for that leak of radiation to decrease the mass by enough to keep it from forming a singularity? The answers are still out there, dear readers. Maybe someday you will be the one to find them!

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