Nearly all middle school students seemed to have learned classical mechanics in their schools. What is classical mechanics? “Classical mechanics is the study of the motion of bodies under the action of physical forces. As is true for any physical model, classical mechanics is an approximation and has its limits - it breaks down at small scales, high speeds, and large gravitational fields - but within its range of applicability (which includes pretty much every single phenomenon in everyday life) it is useful” (Idema). In secondary school, all students learn Newton’s law of motion and the law of gravitation. These two are crucial concepts in classical mechanics. Thus, how do classical mechanics hold? Is it as important as it’s written in the book? At least in my opinion, I reckon that classical mechanics has played a crucial role in human development by making people pay attention to the nature of matter and the capabilities of the universe, making people realize that experiments are just as important or even more important than theoretical reasoning, and profoundly changed the human world, both intellectually and materially.
The study of the motion of objects is an ancient discipline, making classical mechanics one of the oldest and largest disciplines in science, engineering, and technology. In Antiquity, some people began to study the motion of objects. The ancient Greek philosophers, especially Aristotle, were among the first to suggest that abstract principles governed nature. In his book On the Heavens (de Caelo), Aristotle argued that the Earth’s celestial bodies rise or fall to their “natural positions” and stated a correct approximation law that the speed of an object’s fall is proportional to its weight and inversely proportional to the density of the fluid it falls on (Carlo). Aristotle saw a difference between “natural motion” and “forced motion”, arguing that “in the void”, which means a vacuum, objects at rest will remain at rest, and objects in motion will continue to have the same motion. In this way, Aristotle was the first to approach the law of inertia. His views on the physical sciences profoundly influenced medieval scholarship that extended far into the Renaissance (Cline). There is also a tradition dating back to ancient Greece, where mathematics was used to analyze stationary or moving objects, which can be traced back to the work of some Pythagoreans. Additional examples of this tradition include Euclid (on equilibrium), Archimedes (on plane equilibrium, on floating bodies), and Hero (mechanics). Later, Islamic and Byzantine scholars worked based on these works, which were eventually reintroduced or used in the West during the 12th century and the Renaissance. However, these studies were only imaginary, not experimental. As a result, many of the conclusions were wrong. But it has to be said that it was because of them that people began to study the motion of objects. Without their initial imagination, without their thinking about how things move, perhaps classical mechanics would not have been established, and even physics would not have been established. After all, no one would have thought about the nature of matter, and how the universe was established.
Over time, some scientists have come to realize that conclusions cannot be drawn from imagination alone. One of the significant people in classical mechanics was Galileo Galilei. He carried out quantitative experiments by rolling a ball on an inclined plane. His correct theory of accelerated motion seemingly derived from experimental results (Palmieri 2003). Galileo also discovered that objects falling vertically hit the ground at the same time as those projected horizontally so that a uniformly rotating Earth would still have things falling to the ground under gravity. More importantly, it asserts that constant motion is indistinguishable from rest, and thus forms the basis of relativity. He was the first person in classical mechanics and in the whole history of mechanics to use experiments to demonstrate. He taught people the importance of experiments when studying theoretical physics. He pioneered the use of experiments to demonstrate. It’s fair to say that if he hadn’t started to do experiments, people would still be discussing theories on paper rather than getting data from experiments and drawing conclusions based on the data. Aristotle gave people the idea to study the nature of the world, so to speak. Galileo pushed people and showed them how to study the nature of the world.
Another influential person in classical mechanics is Sir Isaac Newton. In 1687, his work, The Mathematical Principles of Natural Philosophy (hereinafter referred to as Principia), was first published. In Principia, Newton laid out the laws of motion and gravity on which he built a major scientific concept that was later replaced by relativity (Newton). In addition, in Principia, both Newton’s second and third laws are given proper scientific and mathematical treatment (Thornton). He also explained the cosmic system according to the laws that had been discovered and analyzed the observed celestial data, such as how satellites move around planets, how planets move around the sun, and how comets’ orbits are determined (Schmitz). At the same time, he also observed and analyzed the free fall and projectile motion of objects on the ground, which for the first time combined the movement of the earth and the celestial body. Newton differed from earlier attempts to explain similar phenomena, which were either incomplete, incorrect, or did not give accurate mathematical expressions, but Newton gave a more complete expression. The combination of Newton’s laws of motion and gravitation provides the most complete and accurate description of classical mechanics (Thornton). Moreover, he proved that these laws applied not only to everyday objects, but also to celestial bodies, and in particular theoretically explained Kepler’s laws of planetary motion. His logic is rigorous, the structure is rigorous, and through observation and experiment, the formation of a complete scientific system. The establishment of classical mechanics laid a solid foundation for the development of the whole natural science, established the basic concepts and basic laws of mechanics, made mechanics become a systematic theoretical knowledge system, and gradually matured and perfect. Classical mechanics not only describes the movement of objects, but also reveals the reasons for the movement of objects so that people can understand how objects move, explain why things move, and enable people to improve the description of the motion state of things from the result of the change to the understanding of the process of change, which greatly changes people’s understanding and view of the world. Last but not least, the combination of classical mechanics and engineering practice, the establishment of applied mechanics, such as hydraulics, mechanics of materials, structural mechanics, etc. River damming, bridge building, and modern means of transportation, such as trains, automobiles, and airplanes, all of these are subject to classical mechanics, and it is because of the discovery of classical mechanics that it is possible to build high-precision machinery. Not only that, but the theories of classical mechanics also apply to the exploration of the universe. Because Newton unified the movements of heaven and earth, people were able to explore the universe through mathematical methods. And even later, people were launching satellites into outer space, building rockets, and so on using Newton’s theories, using the whole of classical mechanics. This greatly promoted the development of human society.
All in all, after about two thousand years of development, the edifice of classical mechanics has been built. From Aristotle to Galileo, from Newton to Einstein, generations of scientists have never stopped searching for the truth. They devoted their whole lives to physics. In the process of classical mechanics research, the most important thing is not the content of the research, but how to conduct the research: asking questions and guesses, conducting experiments, theorizing, and concluding, which is one of the most important contributions of classical mechanics. Of course, it cannot be denied that, despite the limitations of classical mechanics, it can only be discussed at a macro-low speed, classical mechanics theory do have made great contributions to people’s production and life. The theories of physics are not unified yet, but there may soon be a mature theory to unify physics.
Works Cited
Aristotle. On the Heavens (de Caelo) book 13.
Aristotle. Physics Book 4 On motion in a void.
Barbour, J. B. The Discovery of Dynamics: A Study from a Machian Point of View of the Discovery and the Structure of Dynamical Theories. Oxford University Press, 2001.
Cline, Douglas. Variational Principles in Classical Mechanics. River Campus Libraries, 2018
Idema, Timon. “1: Introduction to Classical Mechanics.” Nov 6, 2020, <phys.libretexts.org/Bookshelves/University_Physics/Book%3A_Mechanics_and_Relativity_(Idema)/01%3A_Introduction_to_Classical_Mechanics> , Accessed 30 Nov. 2022.
Palmieri, Paolo. Mental models in Galileo’s early mathematization of nature, Studies in History and Philosophy of Science Part A. 34 (2): 229–264.
Raymond, A. Serway and Cheis, Vuille. College Physics Ninth Edition. Cengage Learning, 2011.
Rovelli, Carlo. Aristotle’s Physics: A Physicist’s Look. Journal of the American Philosophical Association, 2015.
Schmitz, Kenneth S. Physical Chemistry: Multidisciplinary Applications in Society. Elsevier, 2018.
Steele, J. M. Steele. Reading the Principia: The Debate on Newton’s Mathematical Methods for Natural Philosophy from 1687 to 1736. 1 Apr. 2010.
Thornton, S. T. and Marion, J. B. Classical Dynamics of Particles and Systems. Cengage Learning, 2021.
Thornton, Stephen T., and Jerry B. Marion. Classical Dynamics of Particles and Systems. Brooks/Cole, 2004.