The theory that black holes have existed is not new at all. The thought of them first started in 1783 when Rev. John Michell applied Newton's theory of gravity to predict the possibility of so-called "dark stars." Albert Einstein's theory of relativity predicted in 1915 "Schwarzschild singularities." In 1967, these were renamed "black holes." A black hole is collapsed object (usually a star) that has become invisible and has such a powerful gravitational force that nothing, even light, can escape its surface. This is the reason that they are invisible. They are so powerful that one could easily crush an enormous amount of matter into an incredibly small space.
For instance, if the earth were to be squeezed into a black hole, it would end up as the size of a marble. A black hole forms when a super massive star has "used up" all of its nuclear fuel and then collapses under its own gravitational force. This happens because, as a star burns fuel, it creates an outward push, which counteracts the inward pull of gravity. Once the fuel is gone, the internal pressure of the star drops and it can no longer support its own weight. In a monstrous explosion, the outer layers are thrown off. And, at this same moment, the core collapses.
This can happen rather quickly because gravity can crush an object 10, 000 miles across to an object only 10 miles across in about one second. During the time that a black hole is created, the star shrinks down to an infinitely small and infinitely dense point know as the singularity. At this point, all we have ever known about the universe breaks down. Around the singularity there is an imaginary circle called the event horizon. This is the black hole's gravitational boundary where not even light can escape. Once this boundary has been crossed, there is no return.
You could never actually see an object fall into a black hole. As it approaches the event horizon, time would slow down to the point in which it would take an infinite amount of time to reach it. Meanwhile, the black hole's gravitational pull on light would give the effect that the object is fading away. If that object were a person, these are the effects that he would feel: As he fell into the black hole, he would instantly be stretched out because the difference between the gravitational pull on his head and feet would be so powerful, if he could look back as he fell, the entire history of the universe would flash before his eyes (but once inside he is unable to communicate with anyone outside the event horizon), as he neared the singularity, he would feel himself being torn apart atom by atom. As far as we know, reality ceases to exist inside a black hole. In the future, black holes could be greatly advantageous to us.
Only, it would be extremely difficult to tap their immeasurable power. One technological advance black holes could help us achieve is time travel. Most scientists say that constructing a time machine is impossible, but time travel is not against the laws of physics. And, black holes could be the key to this.
Physicists have speculated the existence of wormholes since the 1930's. These are gateways between different parts of the universe. One is made by linking a pair of black holes. By doing this, a tunnel is created through time and space. If you traveled through one end, and exited out the other, you would be in a different time and place.
The only difficulty in this is trying to keep the wormhole from closing while the traveler goes through. If it were to close, the traveler would not be able to survive to make to the other end. Also, scientists have thought that it would physically impossible to travel through the wormhole. One way it could be done is to use some sort of material capable of withstanding the great forces present.
Even so, if we were able to do that, the time machine would have very limited ability. You could not go back to a time when the wormhole has not been created yet. We would also have to live in a society where we have already exploited the energy of black holes. All of this seems very, very difficult - but not impossible. Something else, which could be beneficial to us, is if we could harness the energy of a black hole.
An entire civilization (technologically advanced) could gather enough energy from it to fulfill all of its power requirements. We would have to build a structure that could withstand the immense gravitational forces around the event horizon. It would collect energy from the black hole, but energy taken this way would not be unlimited. In the future, I believe that black holes will be more beneficial to us than threatening. Although the nearest black hole to us is fifteen light years away it would be easier to take advantage of it than have it pose any threat to us. Also, the most super massive black holes are confined to the centers of very distant galaxies.
The only way a black hole could do anything bad to us is if we somehow gained access to one in the future, and an accident occurred. What if the black hole were our only power source and something were to go wrong? What would we do? Maybe black hole technology would fall into the wrong hands. If we were able to make something useful out of a black hole in the future, is it possible for someone to create a destructive weapon out of one? Still, I believe that if we could gain access to a black hole, it would be much more useful than harmful to us. In conclusion, black holes are not theoretical (as they once were) but are a reality. Most of the aspects of black holes seem bad or threatening when first looked at, but it is possible they can be very beneficial to us in the future if we could gain access to one. Time travel, which is not impossible, can be accessible to us using black holes, although it might not be very beneficial if we do not know how to travel correctly.
Finally, the fact that they could provide us with enough energy to fuel an entire society is also very beneficial.