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The World, also called Treatise on the Light (French title: Traité du monde et de la lumière), is a book by René Descartes (1596–1650). Written between 1629 and 1633, it contains a nearly complete version of his philosophy, from method, to metaphysics, to physics and biology.
French is a Romance language of the Indo-European family. It descended from the Vulgar Latin of the Roman Empire, as did all Romance languages. French evolved from Gallo-Romance, the spoken Latin in Gaul, and more specifically in Northern Gaul. Its closest relatives are the other langues d'oïl—languages historically spoken in northern France and in southern Belgium, which French (Francien) has largely supplanted. French was also influenced by native Celtic languages of Northern Roman Gaul like Gallia Belgica and by the (Germanic) Frankish language of the post-Roman Frankish invaders. Today, owing to France's past overseas expansion, there are numerous French-based creole languages, most notably Haitian Creole. A French-speaking person or nation may be referred to as Francophone in both English and French.
René Descartes was a French philosopher, mathematician, and scientist. A native of the Kingdom of France, he spent about 20 years (1629–1649) of his life in the Dutch Republic after serving for a while in the Dutch States Army of Maurice of Nassau, Prince of Orange and the Stadtholder of the United Provinces. He is generally considered one of the most notable intellectual figures of the Dutch Golden Age.
Philosophy is the study of general and fundamental questions about existence, knowledge, values, reason, mind, and language. Such questions are often posed as problems to be studied or resolved. The term was probably coined by Pythagoras. Philosophical methods include questioning, critical discussion, rational argument, and systematic presentation. Classic philosophical questions include: Is it possible to know anything and to prove it? What is most real? Philosophers also pose more practical and concrete questions such as: Is there a best way to live? Is it better to be just or unjust? Do humans have free will?
Descartes espoused mechanical philosophy, a form of natural philosophy popular in the 17th century. He thought everything physical in the universe to be made of tiny "corpuscles" of matter. Corpuscularianism is closely related to atomism. The main difference was that Descartes maintained that there could be no vacuum, and all matter was constantly swirling to prevent a void as corpuscles moved through other matter. The World presents a corpuscularian cosmology in which swirling vortices explain, among other phenomena, the creation of the Solar System and the circular motion of planets around the Sun.
Mechanism is the belief that natural wholes are like complicated machines or artifacts, composed of parts lacking any intrinsic relationship to each other. Thus, the source of an apparent thing's activities is not the whole itself, but its parts or an external influence on the parts.
Natural philosophy or philosophy of nature was the philosophical study of nature and the physical universe that was dominant before the development of modern science. It is considered to be the precursor of natural science.
Corpuscularianism is a physical theory that supposes all matter to be composed of minute particles. The theory became important in the seventeenth century; amongst the leading corpuscularians were Thomas Hobbes, René Descartes, Pierre Gassendi, Robert Boyle, Isaac Newton, and John Locke.
The World rests on the heliocentric view, first explicated in Western Europe by Copernicus. Descartes delayed the book's release upon news of the Roman Inquisition's conviction of Galileo for "suspicion of heresy" and sentencing to house arrest. Descartes discussed his work on the book, and his decision not to release it, in letters with another philosopher, Marin Mersenne.
The Roman Inquisition, formally the Supreme Sacred Congregation of the Roman and Universal Inquisition, was a system of tribunals developed by the Holy See of the Roman Catholic Church, during the second half of the 16th century, responsible for prosecuting individuals accused of a wide array of crimes relating to religious doctrine or alternate religious doctrine or alternate religious beliefs. In the period after the Medieval Inquisition, it was one of three different manifestations of the wider Catholic Inquisition along with the Spanish Inquisition and Portuguese Inquisition.
Marin Mersenne, Marin Mersennus or le PèreMersenne was a French polymath, whose works touched a wide variety of fields. He is perhaps best known today among mathematicians for Mersenne prime numbers, those which can be written in the form Mn = 2n − 1 for some integer n. He also developed Mersenne's laws, which describe the harmonics of a vibrating string, and his seminal work on music theory, Harmonie universelle, for which he is referred to as the "father of acoustics". Mersenne, an ordained priest, had many contacts in the scientific world and has been called "the center of the world of science and mathematics during the first half of the 1600s" and, because of his ability to make connections between people and ideas, "the post-box of Europe". He was also a member of the Minim religious order and wrote and lectured on theology and philosophy.
Some material from The World was revised for publication as Principia philosophiae or Principles of Philosophy (1644), a Latin textbook at first intended by Descartes to replace the Aristotelian textbooks then used in universities. In the Principles the heliocentric tone was softened slightly with a relativist frame of reference. The last chapter of The World was published separately as De Homine (On Man) in 1662. The rest of The World was finally published in 1664, and the entire text in 1677.
Principles of Philosophy is a book by René Descartes. In essence it is a synthesis of the Discourse on Method and Meditations on First Philosophy It was written in Latin, published in 1644 and dedicated to Elisabeth of Bohemia, with whom Descartes had a long-standing friendship. A French version followed in 1647. It set forth the principles of nature—the Laws of Physics—as Descartes viewed them. Most notably, it set forth the principle that in the absence of external forces, an object's motion will be uniform and in a straight line. Newton borrowed this principle from Descartes and included it in his own Principia; to this day, it is still generally referred to as Newton's First Law of Motion. The book was primarily intended to replace the Aristotelian curriculum then used in French and British universities. The work provides a systematic statement of his metaphysics and natural philosophy, and represents the first truly comprehensive, mechanistic account of the universe.
Before Descartes begins to describe his theories in physics, he introduces the reader to the idea that there is no relationship between our sensations and what creates these sensations, thereby casting doubt on the Aristotelian belief that such a relationship existed. Next he describes how fire is capable of breaking wood apart into its minuscule parts through the rapid motion of the particles of fire within the flames. This rapid motion of particles is what gives fire its heat, since Descartes claims heat is nothing more than just the motion of particles, and what causes it to produce light.
According to Descartes, the motion, or agitation, of these particles is what gives substances their properties (i.e. their fluidity and hardness). Fire is the most fluid and has enough energy to render most other bodies fluid whereas the particles of air lack the force necessary to do the same. Hard bodies have particles that are all equally hard to separate from the whole.
Based on his observations of how resistant nature is to a vacuum, Descartes deduced that all particles in nature are packed together such that there is no void or empty space in nature (however, Descartes makes it clear that he does not claim that a void cannot exist in nature, since he lacks the observations necessary to say this with certainty).
Descartes describes substances as consisting only of three elementary elements: fire, air and earth, from which the properties of any substance can be characterized by its composition of these elements, the size and arrangement of the particles in the substance, and the motion of its particles.
The motion of these particles and all other objects in nature are subject to the laws of motion Descartes had observed:
Descartes in Principles of Philosophy added to these his laws on elastic collision.
An elastic collision is an encounter between two bodies in which the total kinetic energy of the two bodies remains the same. In an ideal, perfectly elastic collision, there is no net conversion of kinetic energy into other forms such as heat, noise, or potential energy.
Descartes elaborates on how the universe could have started from utter chaos and with these basic laws could have had its particles arranged so as to resemble the universe we observe today. Once the particles in the chaotic universe began to move, the overall motion would have been circular because there is no void in nature, so whenever a single particle moves, another particle must also move to occupy the space where the previous particle once was. This type of circular motion, or vortex, would have created what Descartes observed to be the orbits of the planets about the sun with the heavier objects spinning out towards the outside of the vortex and the lighter objects remaining closer to the center. To explain this, Descartes used the analogy of a river that carried both floating debris (leaves, feathers, etc.) and heavy boats. If the river abruptly arrived at a sharp bend, the boats would follow Descartes third law of motion and hit the shore of the river since the flow of the particles in the river would not have enough force to change the direction of the boat. However, the much lighter floating debris would follow the river since the particles in the river would have sufficient force to change the direction of the debris. In the heavens, it’s the circular flow of celestial particles, or aether, that causes the motion of the planets to be circular.
As to the reason why heavy objects on Earth fall, Descartes explained this through the agitation of the particles in the atmosphere. The particles of the aether have greater agitation than the particles of air, which in turn have greater agitation than the particles that compose terrestrial objects (e.g. stones). The greater agitation of the aether prevents the particles of air from escaping into the heavens, just as the agitation of air particles forces terrestrial bodies, whose particles have far less agitation than those of air, to descend towards the world.
With his laws of motion set forth and the universe operating under these laws, Descartes next begins to describe his theory on the nature of light. Descartes believed that light traveled instantaneously - a common belief at the time – as an impulse across all the adjacent particles in nature, since Descartes believed nature was without a void. To illustrate this, Descartes used the example of a stick being pushed against some body. Just as the force which is felt at one end of the stick is instantly transferred and felt at the other end, so is the impulse of light that is sent across the heavens and through the atmosphere from luminous bodies to our eyes. Descartes attributed light to have 12 distinct properties:
Physics is the fundamental branch of science. The primary objects of study are matter and energy. Physics is, in one sense, the oldest and most basic academic pursuit; its discoveries find applications throughout the natural sciences, since matter and energy are the basic constituents of the natural world. The other sciences are generally more limited in their scope and may be considered branches that have split off from physics to become sciences in their own right. Physics today may be divided loosely into classical physics and modern physics.
In physics, motion is the change in position of an object with respect to its surroundings in a given interval of time. Motion is mathematically described in terms of displacement, distance, velocity, acceleration, time, and speed. Motion of a body is observed by attaching a frame of reference to an observer and measuring the change in position of the body relative to that frame.
The mechanical philosophy is a natural philosophy describing the universe as similar to a large-scale mechanism. Mechanical philosophy is associated with the scientific revolution of Early Modern Europe. One of the first expositions of universal mechanism is found in the opening passages of Leviathan by Hobbes published in 1651.
Isaac Beeckman was a Dutch philosopher and scientist, who, through his studies and contact with leading natural philosophers, may have "virtually given birth to modern atomism".
The deductive-nomological model, also known as Hempel's model, the Hempel–Oppenheim model, the Popper–Hempel model, or the covering law model, is a formal view of scientifically answering questions asking, "Why...?". The DN model poses scientific explanation as a deductive structure—that is, one where truth of its premises entails truth of its conclusion—hinged on accurate prediction or postdiction of the phenomenon to be explained.
According to ancient and medieval science, aether, also spelled æther or ether and also called quintessence, is the material that fills the region of the universe above the terrestrial sphere. The concept of aether was used in several theories to explain several natural phenomena, such as the traveling of light and gravity. In the late 19th century, physicists postulated that aether permeated all throughout space, providing a medium through which light could travel in a vacuum, but evidence for the presence of such a medium was not found in the Michelson–Morley experiment, and this result has been interpreted as meaning that no such luminiferous aether exists.
In optics, the corpuscular theory of light, arguably set forward by Descartes (1637) states that light is made up of small discrete particles called "corpuscles" which travel in a straight line with a finite velocity and possess impetus. This was based on an alternate description of atomism of the time period. This theory cannot explain refraction, diffraction and interference.
The unmoved mover or prime mover is a concept advanced by Aristotle as a primary cause or "mover" of all the motion in the universe. As is implicit in the name, the "unmoved mover" moves other things, but is not itself moved by any prior action. In Book 12 of his Metaphysics, Aristotle describes the unmoved mover as being perfectly beautiful, indivisible, and contemplating only the perfect contemplation: self-contemplation. He equates this concept also with the active intellect. This Aristotelian concept had its roots in cosmological speculations of the earliest Greek pre-Socratic philosophers and became highly influential and widely drawn upon in medieval philosophy and theology. St. Thomas Aquinas, for example, elaborated on the unmoved mover in the Quinque viae.
Elements of the Philosophy of Newton is a book written by the philosopher Voltaire in 1738 that helped to popularize the theories and thought of Isaac Newton. This book, coupled with Letters on the English, written in 1733, demonstrated that Voltaire had moved beyond the simple poetry and plays he had written previously.
Atomism is a natural philosophy that developed in several ancient traditions.
In early philosophies of psychology and metaphysics, conatus is an innate inclination of a thing to continue to exist and enhance itself. This "thing" may be mind, matter, or a combination of both. Over the millennia, many different definitions and treatments have been formulated. Seventeenth-century philosophers René Descartes, Baruch Spinoza, Gottfried Leibniz, and Thomas Hobbes made important contributions. The conatus may refer to the instinctive "will to live" of living organisms or to various metaphysical theories of motion and inertia. Often the concept is associated with God's will in a pantheist view of Nature. The concept may be broken up into separate definitions for the mind and body and split when discussing centrifugal force and inertia.
Aristotelian physics is a form of natural science described in the works of the Greek philosopher Aristotle (384–322 BCE). In his work Physics, Aristotle intended to establish general principles of change that govern all natural bodies, both living and inanimate, celestial and terrestrial – including all motion, quantitative change, qualitative change, and substantial change.
Mechanical explanations of gravitation are attempts to explain the action of gravity by aid of basic mechanical processes, such as pressure forces caused by pushes, without the use of any action at a distance. These theories were developed from the 16th until the 19th century in connection with the aether. However, such models are no longer regarded as viable theories within the mainstream scientific community and general relativity is now the standard model to describe gravitation without the use of actions at a distance. Modern "quantum gravity" hypotheses also attempt to describe gravity by more fundamental processes such as particle fields, but they are not based on classical mechanics.
The General Scholium is an essay written by Isaac Newton, appended to his work of Philosophiæ Naturalis Principia Mathematica, known as the Principia. It was first published with the second (1713) edition of the Principia and reappeared with some additions and modifications on the third (1726) edition. It is best known for the "Hypotheses non fingo" expression, which Newton used as a response to some of the criticism received after the release of the first edition (1687). In the essay Newton not only counters the natural philosophy of René Descartes and Gottfried Leibniz, but also addresses issues of scientific methodology, theology, and metaphysics.
In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ultimately composed of atoms, which are made up of interacting subatomic particles, and in everyday as well as scientific usage, "matter" generally includes atoms and anything made up of them, and any particles that act as if they have both rest mass and volume. However it does not include massless particles such as photons, or other energy phenomena or waves such as light or sound. Matter exists in various states. These include classical everyday phases such as solid, liquid, and gas – for example water exists as ice, liquid water, and gaseous steam – but other states are possible, including plasma, Bose–Einstein condensates, fermionic condensates, and quark–gluon plasma.
Ancient, medieval and Renaissance astronomers and philosophers developed many different theories about the dynamics of the celestial spheres. They explained the motions of the various nested spheres in terms of the materials of which they were made, external movers such as celestial intelligences, and internal movers such as motive souls or impressed forces. Most of these models were qualitative, although a few of them incorporated quantitative analyses that related speed, motive force and resistance.
Quaestiones quaedam philosophicae is the name given to a set of notes that Isaac Newton kept for himself during his earlier years in Cambridge. They concern questions in the natural philosophy of the day that interested him. Apart from the light it throws on the formation of his own agenda for research, the major interest in these notes is the documentation of the unaided development of the scientific method in the mind of Newton, whereby every question is put to experimental test.
The Plastic Principle is an idea introduced into Western thought by the English philosopher Ralph Cudworth (1617–1689) to explain the function of nature and life in the face of both the mechanism and materialism of the Enlightenment. It is a dynamic functional power that contains all of natural law, and is both sustentative and generative, organizing matter according to Platonic Ideas, that is, archetypes that lie beyond the physical realm coming from the Mind of God or Deity, the ground of Being.
This glossary of physics is a list of definitions of terms and concepts relevant to physics, its sub-disciplines, and related fields, including mechanics, materials science, nuclear physics, particle physics, and thermodynamics.
Michael Sean Mahoney was a historian of science.
Stephen Gaukroger, is a British/Australian historian of philosophy and science. He is Emeritus Professor of History of Philosophy and History of Science at the University of Sydney.
The International Standard Book Number (ISBN) is a numeric commercial book identifier which is intended to be unique. Publishers purchase ISBNs from an affiliate of the International ISBN Agency.