Now that I've spent the last several weeks introducing matter, forces, and the particles associated with these two domains, I'd like to spend the next several weeks reviewing some of the major theories and conceptual approaches in the history of physics. Particle physics remains my favorite area, but I feel it's important to discuss other major topics, as well.
Brian Greene's book The Fabric of the Cosmos, which as I noted in my inaugural posting on this blog greatly inspired my interest in physics, basically presents an intellectual history of the discipline.
Having alluded to the early scientific contributions of Galileo (1564-1642) and Descartes (1596-1650), Greene concludes that:
Many sung and unsung heroes contributed to the rapid and impressive progress that was made, but Newton stole the show. With a handful of mathematical equations, he synthesized everything known about motion on earth and in the heavens, and in so doing, composed the score for what has come to be known as classical physics ...Even today, more than three hundred years later, you can see Newton's equations scrawled on introductory-physics chalkboards worldwide, printed on NASA flight plans computing spacecraft trajectories, and embedded within the complex calculations of forefront research (p. 7).
Isaac Newton (1642-1727) and the fields known variously as Newtonian physics, Newtonian mechanics, and classical mechanics are where I would like to begin my review of theories and conceptual approaches. As noted in a Wikipedia document:
Classical mechanics produces very accurate results within the domain of everyday experience. It is enhanced by special relativity for objects moving with large velocity, near the speed of light. Classical mechanics is used to describe the motion of human-sized objects, from projectiles to parts of machinery, as well as astronomical objects, such as spacecraft, planets, stars, and galaxies, and even microscopic objects such as large molecules.
Classical mechanics would thus appear to hold for a wide variety of situations, anything where the object is not approaching the speed of light nor has a size at the submolecular level, hence the continued vitality of Newton's work.
Newton is well known for his laws of motion. Although these laws involve calculus (of which Newton was a leading developer), his second law can be expressed in the familiar F = ma (force equals mass times acceleration). Newton's other laws involve other familiar terms such as velocity and momentum.
The Physics Classroom website, from Glenbrook South High School in Illinois, illustrates Newtonian physics and related topics of motion, at a high school level.
This ESPN.com document uses examples from ice hockey to illustrate Newton's three laws of motion.
I encourage everyone to try out these linked websites. I think you'll find them educational and fun. I will return to concepts associated with Newton in future postings, such as when I discuss Einstein's theory of general relativity, which presents a contrasting view of gravity from what Newton thought.