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The Mysterious Black Holes
Black Holes have always been mysterious and have been the center of imagination to many books and science fiction movies for generations. Books and movies seem to portray Black Holes as either a way to travel through time or the Black Hole, itself, travels through space causing havoc by sucking everything up it comes into contact with. Although these books and movies make great stories and stir the imagination, we have to remember that they are just that, stories.
The definition of a Black Hole is that they are cold remnants of former stars so dense that no matter or even light is able to escape their powerful gravitational pull. Most Black Holes are small in size, but there are some that are very large. Black Holes were once called "invisible stars" because of the fact that no light can escape it. So, in all actuality, you cannot really see a Black Hole in outer space. A question that is usually asked is, "If you cannot see Black Holes, then how do you know they exist"? Well, scientists look for a star or gas that is behaving strangely, meaning that they may be wobbling or spinning in a matter that does not make sense or no reason for them to be acting in such a matter. They then measure the speed of visible light from that star, or any x-ray or radio waves that are surrounding that object. Knowing the speed and combine that with the laws of gravity they can prove that object is surrounding a Black Hole and not something else. Using this method, scientists today have found billions of Black Holes in the Universe. The nearest Black Hole to Earth is just 1,600 light years away.
Before we have a Black Hole, we have a star that is shining brightly. Gravity and radiation are supporting this star by playing a tug of war to keep the star stable. Once the star begins to die, it begins to lose its fuel and gravity begins to take over and explodes and the core of the star begins to collapse. This is what is called a Supernova.
There are a couple of different types of Black Holes. The most common Black Hole is a Stellar Black Hole. This type is formed by the gravitational collapse of a massive star. They have masses ranging from 5 to 10 solar masses. When talking about measuring in solar masses, it is meant as an astronomical unit of mass equal to the Sun's mass.
Another type is called Super-massive Black Holes, which are just a bigger version of Stellar Black Holes and behave in the same way. There are some characteristics on determining what type of Black Hole is being observed. Aside from the mass being measured, scientists also look at it's spin (yes, Black Holes have an axis) and they also look at it's electrical charge. There is a Super-massive Black Hole at the center of the Milky Way, no need to worry though, it is 30,000 light years away. Intermediate-Mass Black Holes (IMBH) are a hypothetical class of black holes with mass in the range of 100 to one million solar masses. Wow, that is huge. There is an idea that there may be miniature black holes, which scientists believe may have been formed shortly after the "Big Bang", which is thought to have started the Universe about 15 billion years ago.
Black Holes cannot suck up everything in the Universe. Each Black Hole has it's own horizon, much like the gravitational field of a planet. A question that is sure to be asked is, "Do Black Holes move through space?" The answer is yes, they do move through space, such as everything moves in space. Another concern that some people have is, 'What if a Black Hole enters our galaxy and swallows up the Earth?" This scenario is unlikely, at least for the time being. It could happen, but don't worry, you have more of a chance winning the lottery a few times in a row before a Black Hole comes through our galaxy. Just like everything in the Universe, what is born must also die. A Black Hole does die, or actually disappears or evaporates. Depending on the size of the Black Hole, it could take a very long time, but some scientists believe that they do eventually fade out.
Stellar Black Hole
Supermassive Black Hole
John A Wheeler
John Wheeler - An American Theoretical Physicist
John Wheeler (1911 - 2008) coined the term Black Hole back in 1967, while at Prinston University, in which he was a professor of physics since 1938. His work at the University was cut short during World War II, where he helped participate in the development of the U.S. Atomic bomb as part of the Manhattan Project at the Hanford Site in Washington State.
Wheeler was also good friends with Albert Einstein and after the war taught Einsteinian gravity to his students back in the 1950's. In the late 1950's Wheeler came up with the theory of geometrodynamics, which is a program of physical and philosophical reduction of all physical phenomena. He decided to stop teaching that theory back in the 1970's when he could not prove any of the phenomena. Wheeler loved to teach and was known for his high energy lectures, writing with both hands on the chalk board, and making sure he made eye contact with his students.
John Wheeler was awarded numerous honours over the years and received honorary degrees from 18 institutions. Wheeler died from pneumonia in 2008 at the age of 96.
John Mitchell (1724-1793), was one of the most brilliant scientists of his time and at the same time, not very well known. Mitchell was the first to explore the theory of earthquakes and suggest that they might originate as an event at a specific place, like under a volcano. He studied at Cambridge University and taught Hebrew, Greek, Mathematics, and Geology at the same place.
No one knows what John Mitchell looked like, no known painting was ever made, yet you will find pictures of him on the Internet. John Mitchell was described as a short fat man with a dark complexion, which does not compare to the pictures you will find. Michell was good friends with Sir Issac Newton and agreed with Newton's theory that light consists of small material particles.
Mitchell loved astronomy and took every opportunity to study the stars and how they were distributed in the sky. He came up with new mathematics of statistics to astronomy and was the first to imagine that Black Holes existed. This idea came to him while conducting a hypothetical method of determining the mass of stars. He envisioned a case where a star's gravity was so strong that no light could escape it, hence, the beginning of Black Hole discovery.
Peirre LaPlace (1749-1827) was a French physicist, mathematician, and astronomer. He is best known for his investigations into the stability of the Solar System and began his major lifework in 1773, applying Newton's law of gravity to the entire Solar System.
LaPlace influenced a new generation of mathematicians regarding the theory of probability and statistics and was highly regarded for his work in Celestial Mechanics from 1799 to 1825. This work developed a strong mathematical understanding of the motion of the heavenly bodies. LaPlace suggested that the nature of the universe is completely deterministic and contributed in the development of different equations, probability and statistics.