lack Holes, a story for science fiction or is there truth behind their existence. These astrological anomalies are still a wonder to the greatest scientists in the world and not yet identified to truly exist. During this investigation I will be looking into the way in which ideas of Black Holes existence have developed over the years. Furthermore this investigation will also look into the ways in which a Black Hole can be identified and if so; what effects they would have on us. irst, the question of “What is a Black Hole” needs to be answered.
In simple terms a Black Hole is a region of space that has so much mass concentrated in it that there is no way for a nearby object to escape its gravitational pull. Black Holes were once thought to be the monsters of the Universe, devouring everything around them in a frenzied cosmic feast. Black Holes are regions of space where gravity is so strong that not even light can escape, making them impossible to see. But we can see the debris that is being sucked in to these collapsed stars.
Anything that approaches a Black Hole is first torn apart by it’s immense gravitational force and then forms a flat rotating disc that spirals into the hole. The name “Black Hole” was not developed until 1967 but ideas around their existence have existed since the 18th century. The first ideas were put forward in 1783 by Reverend John Michell where he talked of how “light could not escape from a star of the same mean density as the Sun but 500 times bigger”. These first ideas on Black Holes were based around speculations about Black Holes hinged on ideas about the nature of light.
By the end of the 17th century it was known that light travelled through space at a great speed. Then in 1965 Ole Romer made one of the first estimates at the speed of light after studying the path of one of Jupiter’s moons. Then in the early 1900’s Albert Einstein united the concepts of space and time; first discovered by Isaac Newton, with ideas of light itself. The result was that Einstein realised that space and time had to be dynamic entities that were themselves responsible for the force of gravity and this lead to his general theory of relativity.
Black Holes however represent an extreme where gravity dominates and so space and time become distorted beyond recognition. The mathematical theory behind black holes (I shall explain this later) arises from Einstein’s general theory of relativity, but the idea of an object from which light can not escape was first thought of in the 18th century. When these ideas were stated by Michell (these are talked about at the beginning of the paragraph) it was generally held that light consisted of particles that travelled in straight lines through space.
This idea arose from an interpretation of Newton’s ideas. The consequence of Newton’s laws of motion and gravitation had been studied exhaustively for a century and after much experimentation were deemed as being extremely accurate. Therefore towards the end of the 18th century these laws were being applied to all situations whether astronomical or Earth bound. It was from this that Michell was able to predict that surely light particles would have the same forces of gravity acting upon them as would you or I and therefore they were not excluded from the laws of gravity.
Therefore he predicted that an object could exist that had such a great gravitational pull that it would be greater than the speed of light and so nothing would be able to escape this object. The object was then later named a “black hole”. As Black Holes have not be proven their existence is only hypothetical and so we have to visualise them in our mind In order to identify “what is a Black Hole” we have to think about this in practical terms. This can be done by detailing the following scenario. Suppose that you are standing on the surface of a planet. You throw a rock straight up into the air.
Assuming you don’t throw it too hard, it will rise for a while, but eventually the acceleration due to the planet’s gravity will make it start to fall down again. If you threw the rock hard enough, though, you could make it escape the planet’s gravity entirely. It would keep on rising forever. The speed with which you need to throw the rock in order that it just barely escapes the planet’s gravity is called the “escape velocity. ” As you would expect, the escape velocity depends on the mass of the planet: if the planet is extremely massive, then its gravity is very strong, and the escape velocity is high.
A lighter planet would have a smaller escape velocity. The escape velocity also depends on how far you are from the planet’s centre: the closer you are, the higher the escape velocity. Now imagine an object with such an enormous concentration of mass in such a small radius that its escape velocity was greater than the velocity of light. Then, since nothing can go faster than light, nothing can escape the object’s gravitational field. Even a beam of light would be pulled back by gravity and would be unable to escape.
