11 Amazing Facts About Black Holes

September 22, 2015

Black hole Cygnus X 1

Black holes are the enigma of the universe.  They are the only things in the cosmos known to use their incredible gravitational force to trap and hold light.  Scientists continue to find new things about them that boggles the mind.  Here are a few of them.

Black holes aren’t all huge.  They come in many shapes and sizes.  Sure there are those that are at the center of a galaxy, causing everything to be swept up in them if things get too close, but there are black holes that can be have the mass of a mountain, or are even the size of an atom.

Although Einstein’s theory of relativity explains how black holes are formed, the discovery of black holes was made by Karl Schwarzschild.  He came up theory the same time as Einstein’s famous one, and his work produced the Schwarzschild radius.  This was a measurement of how small an object would have to be compressed to make a black hole.  When something is compressed, the object becomes more dense and produces a greater gravitational force.  There is a specific radius of a sphere that an object can be compressed to form a black hole.

Another discovery by physicist Stephen Hawking in 1974 explained that black holes can spit material out as well as take it in.  Black hole evaporation, also known as Hawking radiation, occurs when a black hole’s mass is expelled out of the hole, and over time the black hole will cease to exist since there is nothing left.

Strange things happen with time around black holes.  If it were possible to stick a guy named Stan in a black hole (which would be impossible since he would be pulled into nothingness), and put a friend of his, Fran, outside of the black hole, a curious thing would happen.  According to Einstein’s theory of relativity, from Fran’s perspective, Stan’s time would appear as slowing while getting slower.  Stan would think his time is normal and that Fran was going much faster.  This is the effect of the black hole when going at speeds close to the speed of light.  Time and space are warped.

The event horizon of a black hole is that spot where the gravitational pull of the black hole can’t be escaped.  That’s actually a good thing because it means one super massive black hole can’t continue to get larger and eventually swallow up the universe.  A black hole could be observed from a safe distance, if we were ever able to get that close.  The nearest black hole is 20,000 light years away.


You can’t “see” a black hole, even with any number of instruments or detecting equipment.  A black hole is black for one, since no light can escape it.  If scientists can’t see it, then how do thy know it’s there?  They look at the effects on things around a black hole; how it forcefully pulls on stars or other celestial bodies for example.  By using instruments that can see these effects, such as a burst of x-rays from a star that is being pulled apart, scientists can “see” the entity acting on it.

Black holes are incredibly efficient at producing energy.  Material near the black hole’s event horizon moves faster than material at the outer edges due to the super gravitational forces there.  The material near the edge of the event horizon is heated to billions of degrees Fahrenheit, and the mass of the material is converted into energy.  This produces what is called blackbody radiation.  A black hole can transform 10% of this mass into energy.  That’s quite a difference as compared to nuclear fusion, which can change only 0.7% of mass into energy.

Black holes are thought to be at the center of a galaxy, and yes we have one in our own backyard.  But we’ll be long gone before it poses a risk for Earth.  Our own black hole is believed to be incredibly massive, four million times more massive than our Sun.  Try to wrap your head around that.

An interesting thing happens when super massive stars, much greater in size than our Sun, finally run out of nuclear fuel.  These stars get overrun by gravity, and they are unable to keep their shape.  This is called a supernova, and the core of the star collapses while other layers get blown into space.  What’s left is an area that has virtually no volume and density that is infinite.  That is exactly what a black hole is.  No light can escape such a crushing place.

There are some that believe that a worm hole exists if you entered a black hole.  A worm hole is a theoretical passage to another part of the universe.  Current science is unable to explain how this could be, but there is no shortage of things to learn about wormholes, if they even exist.  Others believe a black hole is a crushing void.  I think I’ll vote for the wormhole.

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About the author 

Daniel Ganninger - The writer, editor, and chief lackey of Knowledge Stew, the author of the Knowledge Stew line of great trivia books, and editor of Fact World and the Knowledge Stew sister site on Medium. I hope you find things here to annoy those around you with your new found knowledge.

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