You may have heard the phrase “Newtonian world” a lot. Almost all experts use this conception in various scientific disciplines, including philosophy, social sciences, psychology, physics, economics, Etc. All of us and tenth-year students in different disciplines become familiar with Newton’s laws at the beginning of our school year but usually do not understand the depth. Because of the nature of textbooks that are mainly written to learn problem-solving or prepare for the job market. If one comes to a correct understanding of Newton’s evolution of human knowledge, he certainly recognizes that understanding the Newtonian world is vital to every human being.
Regardless of what is our field of science, we owe it to Newton’s genius to be able to look at any object on or outside of the earth with a unique view and not divide them into two types.
To look at all the objects of the universe with a unique view and subject them under the unique rules is the result of Newton’s efforts in his books.
Newton’s Book of Mathematical Principles of Natural Philosophy is not just a book on mathematics or physics! Newton has created a new plan for human knowledge of the world and its surroundings in this book. To better understand the position of this book, it is good to know the position of world human knowledge from around him in the Newton era. In this article, we will do this vital subject. It is also good to say that reading this article will be helpful for students in years 10, 11, 12, and other students to understand better the issues of physics, mathematics, or even philosophy. Stay with us.
The situation of physics in the Newton era
Newton was living when Aristotelian physics contained many ambiguities and drawbacks, which had dominated the world before Newtonian physics. For example, according to Aristotelian physics, the celestial spheres were absolute, colorless, pure, and immutable beings made of a different and higher kind than terrestrial bodies. But observations had done by Galileo’s telescope showed celestial spheres were composed of rock and soil and, therefore, should follow the same laws as earth. So scientists were looking for laws that would create a kind of unity between earth and sky and explain earthly and celestial objects together. Another thing that happened in Newton’s era was the revelation of the shortcomings of Aristotle’s doctrine of four causes. In Aristotle’s philosophy, any phenomenon may have four causes: material, formal, efficient, and final. The final cause means the ultimate goal of a phenomenon or event. For example, becoming a red apple is the final cause of the blossoming of an apple tree. The final cause in Aristotle’s physics became a concept called the natural position of a substance or its natural state. For example, the natural place or the final place of a seashell is the seafloor because it is made of rock, and the nature of the rock is such that it should be lower than water. The natural position of air is also higher than water because the nature of air is such that it must be higher than water. The location of the four elements, earth, water, fire, and air, was similarly explained in Aristotelian physics. We must be fair, of course, as Aristotelian physics was able to explain many natural phenomena. For example, when wood burns because the natural location of the fire is higher than the soil or earth, the fire element comes out of it and goes up, leaving the soil element (ash). But in Newton’s era, there were severe flaws in this way of thinking.
Another critical weakness of Aristotelian physics was that it could only explain phenomena qualitatively and could not explain them quantitatively. For example, it can only say that a substance gradually turns into steam by heating water and does not change its shape. But this question of how many minutes or seconds after heating, water begins to evaporate was a question that Aristotelian physics could not precisely answer.
The next problem that arose for Aristotelian physics was the free-fall experiment that exposed Galileo. According to Aristotle, when we drop two bodies from a height simultaneously, the heavier object reaches the ground sooner. Although this is consistent with our daily experience, it is interesting to note that Galileo’s experiment showed that this was not related to the weight of the heavy body but related to the friction of the air. His experiment showed that when two objects are in a vacuum and, the friction is zero, both bodies will reach the ground in a moment.
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Inversion of the relationship between nature and mathematics
In the field of mathematics, a strange situation occurred. Before newton’s era, scientists thought that nature followed beautiful and transcendental mathematical models, and whatever we are experiencing had to follow a fascinating pre-determined mathematical hierarchy. Although this way of thinking about mathematics still prevails in parts of science today and helps to advance science. It was determined in Newton’s era that the relationship between mathematics and nature could be reversed. This means that sometimes, after discovering a physical and experimental theory, mathematicians may seek to create its mathematics. Similar something happened to Newton, and he created the mathematics needed for his laws.
Astronomy and the questioning of the world of onion skin
An earthquake had arisen in astronomy and planetary science, and Ptolemy’s geocentric model for the universe was questioned after 2000 years by Copernicus, and many scientists considered earth instead of the Sun to be the universe’s center.
At the same time as Copernicus, the Galileo telescope showed Jupiter’s moons to scientists, and Ptolemy had not said anything about it.
Another breakthrough in astronomy came from Kepler, that denied Plato’s brief about the path of the planets. Using the conical geometry of Apollonius was discovered about 1800 years before Kepler, he showed that the path of the planets is not a perfect circle but an ellipse. According to this model, the Sun was at one of this ellipse.
Thus the Platonic notion of the orbit of the planets, which had prevailed for about 2,000 years, had disappeared. According to Kepler’s experimental formulas, the sum of the distances of each celestial sphere from the Sun and a hypothetical fixed point is always a constant value. Interestingly this is precisely the definition of an ellipse. During these years, Ptolemy’s idea was gradually pushed aside. This theory had considered the world as intertwined layers resembling an onion.
The Mathematical Principles of Natural Philosophy, a book that built a new framework for science!
If one considers the above set of events and visualizes the body of science in his mind, he will find that the framework of human science was disintegrated in Newton’s era. Before Newton, there were misconceptions and false theories in science, but a set of consistent theories convinced seekers of science to some extent. Perhaps this is why, despite serious criticisms of the ancient sciences, past theories were still taught entirely, and the previous system was still in place.
For replacing the new theories, it was necessary to create a consistent framework that could unify the new and past observations in a simple set of rules. At the same point, the value of Newton’s work in the “Mathematical Principles of Natural Philosophy” determines. Newton developed formulas that could connect the observations of spheres and earth by presenting his laws. Before Newton, many scientists realized that there must be one or more specific natural forces between objects on earth or in heaven, but the main point was to present a formula or formulas that would explain all the observations together. What are these formulas, and are they just a number or a few? Are they the same or different on earth and in the spheres? These were questions that no one had not could answer.
Newton’s laws were able to explain Galileo’s observations of the free fall of objects and accurately calculate the variables associated with projectile motion. These laws were used for relation between the celestial spheres and accurately predicted their elliptical paths. Newton describes all of this in his pioneering book.
Galileo had researched well about gravitational acceleration in the earth. Newton began with the idea of extending the earth’s gravitational acceleration to the moon. Newton’s research showed that this force could explain the moon’s movement around the earth. He then tested different formulas to see which one could explain Kepler’s three rules about celestial spheres and their elliptical motion. Kepler’s formulas were experimental and only accurate about the distance between the spheres and their motion. But, the mathematical rule that Newton discovered was universal, and in addition to explaining how celestial spheres move, it was also about the motion of a projectile and the free fall of objects, which was the miracle of Newton’s theory.
After Newton’s book was published, the world changed for scientists completely, and the earth and the sky unified. The heaven spheres were no longer inaccessible and mysterious objects for man, and the unity and rationality of the world became more apparent to Man. In this way, Man was able to make better and more accurate weapons by knowing the rules of the projectile, and by knowing the rules of the heavens, he was able to dominate space. With the elimination of Ptolemy’s system, which considered the universe to have ten constellations and limited it, the hypothesis of the infinity of the universe arrived in the human mind, and more profound questions about creation were designed for the man. The important thing about this book is that reading it is required for anyone interested in knowing the sweet story of new science and its developments.
The English version of this book, which was written by Newton in Latin, follows.