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Imagine being a space traveller of the future - your ship is disabled, drifting off course and you’re working at fever pitch to repair navigation and communications because you know you’re dangerously close to a black hole. If you keep drifting your ship will be drawn into its intense gravitational pull. Black holes devour everything around them, dust, matter, gas, other stars, planets, light that’s travelling at 670, 615, 600 miles per hour -- and unfortunate space travellers.
Black holes were first mentioned in the year 1783 by British astronomer, John Mitchell, but his theories were largely poo-pooed by the scientific community as ridiculous or impossible. The simplest definition of a black hole is - a cosmic body, in most cases a dying star, that generates intense gravity from which nothing can escape, not even light.
All stars eventually burn out and die when their source of fuel runs out. Our sun is a star and in about 8-9 billion years its fuel tank will run dry. As it begins to cool the sun will collapse in on itself, or implode. This cataclysmic reaction will happen in a matter of seconds and create what is known as a “white dwarf”. In stars that are larger than our sun there is an alternate reaction. Once they self-destruct, in this case exploding outwards, they become even smaller than a white dwarf and are typically known as a blinding white mass called a “supernova”. When a tiny part of the star remains intact and is compressed by gravity it’s called a “neutron star”. Giants that self-destruct and shrink to an even smaller size than a neutron star are what astronomers call black holes.
A collapsed star that was 10-12 times bigger than our sun would become a black hole no larger than 40-50 miles across. This is why astronomers say black holes are so hard to detect. They are virtually invisible, sucking in everything around them and emitting neither light nor radio waves. There is really no way of knowing how many black holes exist in our universe. Some experts believe that as stars continue dying, enough black holes might eventually be created that one day the entire universe will be sucked up and disappear in the blink of an eye.
Since 1974, Dr. Stephen Hawking, Cambridge University cosmologist, has done intense research into black holes and how they work. His ground-breaking studies have shown that not all black holes are invisible. Using theories of quantum mechanics and relativity, he has discovered that energy particles around the outside of black holes do sometimes emit light. But this occurs very rarely. He has also suggested that many tiny black holes were created during the “big bang”. As they lose mass, sub-atomic particles called protons and anti-protons are created (think “matter and anti-matter” referred to in science fiction stories). Since neither can exist side-by-side, they annihilate each other. This reaction creates an energy drain inside the black hole until its eventually destroyed.
More recently British and American astronomers have speculated that not all black holes are created from dying stars, that other “supermassive” black holes are formed by collapsing quasars and entire galaxies. In 1994 Hubble Telescope photos showed that there’s a supermassive black hole in the middle of the M87 galaxy, its mass that of 2-3 billion suns. There is also evidence that a similar, but slightly smaller massive black hole, resides in the centre of our Milky Way.
Now back to our unfortunate space traveller -- he’s been pulled into what is called the “event horizon” of a black hole. This is the region where light can’t escape or be sucked back inside. Scientists believe that here time virtually stands still or moves very, very slowly. What will become of the space traveller? Is he stranded in eternity forever? Probably not. Gravity continues pulling him in and as he passes through the edge of the event horizon time begins to go backward. The intense gravity of the black hole will inevitably suck his space craft into its centre and rip it apart. This black hole was a small one, the destruction of our doomed space explorer taking less than one second from start to finish. A black hole would have to be immense, perhaps even limitless, for any human being to experience these effects. Of course it’s very doubtful he’d live to tell anyone about it.
While some experts argue over the existence of black holes others have proposed some rather wild theories, like harnessing them to create useable energy or as outer space garbage cans. There are even those that believe the 1908 blast in Tunguska, Russia, that levelled over 2000 square miles of forest, was caused by a tiny black hole that passed through the earth for less than a split second.
Science fiction writers have used the various theories surrounding black holes for book and screenplay ideas, naming them “wormholes”, small space anomalies that allow for rapid transport of their fictional characters from one point to another. These points of origin would be millions, perhaps even billions of miles apart. Some could even lead to other dimensions. Many people might laugh at such wild and impossible ideas. With the little they know about wormholes, scientists claim the mathematics surrounding them is virtually impossible, that they’d be very unstable. But other writers like Jules Verne have shown us that sometimes their wild and impossible ideas can become real fact. So, who knows, in the far distant future, humans might be using black holes to travel back in time and wormholes to take vacations to other dimensions.
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