One galactic mystery explained: black holes

The black hole. What is it? Where is it? Where did it come from? How many of them are there?

Are black holes dangerous?  Are black holes visible?    

Many astronomers and scientists believe that some regions of space generate so much gravity that they act as if they were vacuum cleaners. As a result, anything that comes very close to those regions gets sucked into them. The matter that is sucked in is crushed to zero size because of the intense gravity. This matter disappears forever.

The boundary of these great vacuums is called the “event horizon� and it is formed by the rays of light that can’t get away from the black hole; they stay there forever. Not even light, the fastest thing in our universe, can travel fast enough to overcome the gravity there. In 1969, John Archibald Wheeler was the first to name these dark and devouring voids black holes.

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How are black holes created? In general, stars last for billions of years before collapsing due to loss of their original fuel and energy. If a star is large enough, at least three-and-a-half times the size of our sun, there is nothing to stop it from collapsing into a black hole. Two scientists, J.R. Oppenheimer and H. Snyder of the University of California at Berkeley, were the ones who in 1939 presented and proved this case of the size of the star that by collapsing ends up as a black hole.

Scientists believe that anything can form a black hole, i.e., stars, planets and even people, when these objects are condensed into the minuteness that makes a black hole. But realistically, only stars with the mass three-and-a-half times that of our sun or more naturally form black holes.

They recognize that black holes come in at least two categories. There are stellar black holes, which form from the collapse of stars. And there are galactic black holes that hang out in the core of a galaxy. The giant M87 galaxy is where the marvelous Hubble Space Telescope discovered swirling gases that stretched out as far as 500 light years around a huge galactic black hole.

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Since the first Hubble discovery there has been more and more evidence piling up to support the existence of other galactic black holes. Many astronomers claim that black holes exist in the center of all or most galaxies. They believe that there may be up to 1 million black holes in our Milky Way galaxy. If that is true, imagine the billions and billions and billions of black holes out in space. And remember that the black hole is not visible itself, but only through its activities.

Our sun will never become a black hole, according to scientists and astronomers. It is not large enough, although it will last for another 5 billion years as it decreases in size until it finally collapses.

Are we in any danger of falling into a black hole? The answer is “no,� even though astronomers believe that there is a super large black hole at the center of our Milky Way galaxy.

We are located on one of the spiral arms of our galaxy, very far from the center. With that distance between us, the black hole’s attractive force will not pull us into it.

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Is the black hole really black?  The answer is “no,â€� according to the British science professor, Stephen Hawking. In fact, the black hole is actually a three-dimensional object. It is not a hole but a sphere. As a matter of fact, we cannot see the objects that are called black holes.

Think about this question: “How do you find a black hole?� Remember, you can’t see it. Scientists have found a way to accomplish this. They know that black holes exert an enormous amount of gravity on nearby objects. And so while scientists cannot see a black hole, they can see the effect it has on nearby objects and surrounding matter.

Black holes are there in many sizes, depending upon the size of the object from which the black hole was formed. Do black holes live forever? Professor Hawking says “no.â€� He believes that the black hole loses energy and mass through what he calls “Hawking radiationâ€� and that ultimately the black hole will no longer have enough mass to curve the space around it. It would then no longer be a black hole.  

Scientists are exploring methods of making a black hole in their laboratory. What an idea! They  are far from completion, and they must realize that they might be too close to that black hole to be able to avoid being attracted into it and becoming a tiny dot at the black hole’s center.

Sidney X. Shore is a scientist, inventor and educator who lives in Salisbury and holds more than 30 U.S. patents.