Gravity represents a fundamental force in the universe that binds all matter and indeed dark matter together. It is a force that can be used to explain the apple falling from the tree to the workings and orbits of the celestial bodies. The following paper explores the notion of Gravity as it represents such a fundamental force within the universe as well as how it has shaped our understanding of reality and influences us on a day to day basis.
As every lay person knows, gravity is the force that keeps our feet on the ground which is an amazing feat considering the Earth is flying through the universe at roughly 67,000 miles per hour. Although Humans do not often question why everything remains ‘stuck’ to the surface of the planet or why when we pour orange juice it doesn’t float to the top of the glass, the answer is simply that the gravitational pull of the earth attracts all things with any mass towards its center.
However, gravity as a force affects many more things than the objects on the Earth. For example the moon remains in its orbits around the Earth precisely because it, as an object with mass, is drawn towards the gravitational pull of the earth (as an object with a larger mass). As well as gravity being able to keep the moon in its rotation around the earth, the gravity of the moon affects the tides by exerting a level of force on the Earth. This is why the tides are set by the astronomic position of the moon, thus high tides are dictated and predicted by the relative position of the moon so in spring, when the moon is in a close orbit with the earth, is when the tides are highest. The first person to develop a coherent theory of gravity was Sir Isaac Newton. Newton was a mathematician and physicist who lived around three centuries ago. Sir Isaac Newton was born in England in 1643 and was a man of many talents who specialized in: astronomy, mathematics, physics, and alchemy. In 1687 he published his greatest work Philosophiae Naturalis Principia Mathematica. This work is considered to be one of the most influential books in the history of science because it laid down the fundamental principles of classical mathematics and physics.
The legend of Newton was that he was sitting under an apple tree when an apple fell and hit him on the head which made him consider why object naturally fell, or were attracted towards, the Earth. What Newton explored was the observable force that affected all object trajectory and speed. After further examination Newton discovered the level and amount of force could be measured and predicted which gave rise to his theory of gravity. Newton’s basic mathematical model which was called Newton’s Law of Universal Gravitation postulated that every point of mass in the galaxy attracted, to some degree, every other point of mass in the universe. This is gravity in its most basic form. The ramifications of this theory mean that when a human jumps in the air the mass they lift off the planet is not only attracted and drawn back to the earth, but to a microscopic degree the earth’s mass is also drawn towards the jumping body. While it seems that a person jumps and is pulled back to the ground what actually happens at the same time is the earth moves very slightly towards the person.
In the Philosophiae Naturalis Principia Mathematica Newton describes this principle of universal gravitation as well as the three laws of motion. These theories have dominated scientific though and provided the basic framework for scientific inquiry for over three century’s and are still used to try an explain more complex theories such as string theory and quantum mechanics. At the heart of Newton’s theory is the notion that the earth and the celestial bodies are all governed by the same set of natural laws which in turn removed the final scientific doubts that the earth was the center of the universe. In Newtonian physics there are a couple of factors that affect the gravitational force of an object. These are: mass, distance and placement of other bodies of mass.
Thus the amount of gravity on earth varies from point to point. Mass is a particularly important factor to consider as the greater the mass the greater the gravitational pull. Distance between objects also plays an important role as the greater the distance equals less of a gravitational pull on an object. Gravity has been used to explain the tides, the movement of celestial bodies such as the moon rotation around the Earth and the Earth’s orbit around the Sun. Gravity is the natural force of attraction, but also affects time itself. When there is a higher level of gravity time moves faster than normal. This has been shown in many experiments when two stop watches are set off at the same instant, one at the top of a mountain and one at the bottom. Even on earth there is a slight difference due to the differing levels of gravity experienced with the stopwatch closer to the earth and the one further away. Gravity is a fundamental force that affects us all and is considered one of the building blocks of all physics and mathematics primarily due to the work of Sir Isaac Newton.