Wednesday, January 12, 2011
Early life of Thomas alva edison
Thomas Edison was born in Milan, Ohio and grew up in Port Huron, Michigan. He was the seventh and last child of Samuel Ogden Edison, Jr. (1804–96, born in Marshalltown, Nova Scotia, Canada) and Nancy Matthews Elliott (1810–1871).[2][citation needed] His father had to escape from Canada because he took part in the unsuccessful Mackenzie Rebellion of 1837.[citation needed] Edison considered himself to be of Dutch ancestry.[3] In school, the young Edison's mind often wandered, and his teacher, the Reverend Engle, was overheard calling him "addled". This ended Edison's three months of official schooling. Edison recalled later, "My mother was the making of me. She was so true, so sure of me; and I felt I had something to live for, someone I must not disappoint." His mother homeschooled him.[4] Much of his education came from reading R.G. Parker's School of Natural Philosophy and The Cooper Union. Edison developed hearing problems at an early age. The cause of his deafness has been attributed to a bout of scarlet fever during childhood and recurring untreated middle-ear infections. Around the middle of his career Edison attributed the hearing impairment to being struck on the ears by a train conductor when his chemical laboratory in a boxcar caught fire and he was thrown off the train in Smiths Creek, Michigan, along with his apparatus and chemicals. In his later years he modified the story to say the injury occurred when the conductor, in helping him onto a moving train, lifted him by the ears.[5][6] Edison's family was forced to move to Port Huron, Michigan, when the railroad bypassed Milan in 1854,[7] but his life there was bittersweet. He sold candy and newspapers on trains running from Port Huron to Detroit, and he sold vegetables to supplement his income. This began Edison's long streak of entrepreneurial ventures as he discovered his talents as a businessman. These talents eventually led him to found 14 companies, including General Electric, which is still in existence and is one of the largest publicly traded companies in the world.
Thomas alva edison
Thomas Alva Edison (February 11, 1847 – October 18, 1931) was an American inventor, scientist, and businessman who developed many devices that greatly influenced life around the world, including the phonograph, the motion picture camera, and a long-lasting, practical electric light bulb. Dubbed "The Wizard of Menlo Park" (now Edison, New Jersey) by a newspaper reporter, he was one of the first inventors to apply the principles of mass production and large teamwork to the process of invention, and therefore is often credited with the creation of the first industrial research laboratory.[1]
Edison is considered one of the most prolific inventors in history, holding 1,093 US patents in his name, as well as many patents in the United Kingdom, France, and Germany. He is credited with numerous inventions that contributed to mass communication and, in particular, telecommunications. These included a stock ticker, a mechanical vote recorder, a battery for an electric car, electrical power, recorded music and motion pictures. His advanced work in these fields was an outgrowth of his early career as a telegraph operator. Edison originated the concept and implementation of electric-power generation and distribution to homes, businesses, and factories – a crucial development in the modern industrialized world. His first power station was on Manhattan Island, New York.
Edison is considered one of the most prolific inventors in history, holding 1,093 US patents in his name, as well as many patents in the United Kingdom, France, and Germany. He is credited with numerous inventions that contributed to mass communication and, in particular, telecommunications. These included a stock ticker, a mechanical vote recorder, a battery for an electric car, electrical power, recorded music and motion pictures. His advanced work in these fields was an outgrowth of his early career as a telegraph operator. Edison originated the concept and implementation of electric-power generation and distribution to homes, businesses, and factories – a crucial development in the modern industrialized world. His first power station was on Manhattan Island, New York.
Newton law of gravitation
Newton's law of universal gravitation
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Classical mechanics
\mathbf{F} = \frac{\mathrm{d}}{\mathrm{d}t}(m \mathbf{v})
Newton's Second Law
History of classical mechanics · Timeline of classical mechanics
[show]Branches
Statics · Dynamics / Kinetics · Kinematics · Applied mechanics · Celestial mechanics · Continuum mechanics · Statistical mechanics
[show]Formulations
* Newtonian mechanics (Vectorial mechanics)
* Analytical mechanics:
o Lagrangian mechanics
o Hamiltonian mechanics
[show]Fundamental concepts
Space · Time · Velocity · Speed · Mass · Acceleration · Gravity · Force · Impulse · Torque / Moment / Couple · Momentum · Angular momentum · Inertia · Moment of inertia · Reference frame · Energy · Kinetic energy · Potential energy · Mechanical work · Virtual work · D'Alembert's principle
[show]Core topics
Rigid body · Rigid body dynamics · Euler's equations (rigid body dynamics) · Motion · Newton's laws of motion · Newton's law of universal gravitation · Equations of motion · Inertial frame of reference · Non-inertial reference frame · Rotating reference frame · Fictitious force · Linear motion · Mechanics of planar particle motion · Displacement (vector) · Relative velocity · Friction · Simple harmonic motion · Harmonic oscillator · Vibration · Damping · Damping ratio · Rotational motion · Circular motion · Uniform circular motion · Non-uniform circular motion · Centripetal force · Centrifugal force · Centrifugal force (rotating reference frame) · Reactive centrifugal force · Coriolis force · Pendulum · Rotational speed · Angular acceleration · Angular velocity · Angular frequency · Angular displacement
[show]Scientists
Galileo Galilei · Isaac Newton · Jeremiah Horrocks · Leonhard Euler · Jean le Rond d'Alembert · Alexis Clairaut · Joseph Louis Lagrange · Pierre-Simon Laplace · William Rowan Hamilton · Siméon-Denis Poisson
v · d · e
The mechanisms of Newton's law of universal gravitation; a point mass m1 attracts another point mass m2 by a force F2 which is proportional to the product of the two masses and inversely proportional to the square of the distance (r) between them. Regardless of masses or distance, the magnitudes of |F1| and |F2| will always be equal. G is the gravitational constant.
Newton's law of universal gravitation states that every massive particle in the universe attracts every other massive particle with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. (Separately it was shown that large spherically-symmetrical masses attract and are attracted as if all their mass were concentrated at their centers.) This is a general physical law derived from empirical observations by what Newton called induction.[1] It is a part of classical mechanics and was formulated in Newton's work Philosophiae Naturalis Principia Mathematica ("the Principia"), first published on 5 July 1687. (When Newton's book was presented in 1686 to the Royal Society, Robert Hooke made a claim that Newton had obtained the inverse square law from him – see History section below.) In modern language, the law states the following:
Every point mass attracts every single other point mass by a force pointing along the line intersecting both points. The force is directly proportional to the product of the two masses and inversely proportional to the square of the distance between the point masses:[2]
F = G \frac{m_1 m_2}{r^2}\ ,
where:
* F is the magnitude of the gravitational force between the two point masses,
* G is the gravitational constant,
* m1 is the mass of the first point mass,
* m2 is the mass of the second point mass, and
* r is the distance between the two point masses.
Assuming SI units, F is measured in newtons (N), m1 and m2 in kilograms (kg), r in meters (m), and the constant G is approximately equal to 6.674×10−11
N m2 kg−2.[3] The value of the constant G was first accurately determined from the results of the Cavendish experiment conducted by the British scientist Henry Cavendish in 1798, although Cavendish did not himself calculate a numerical value for G[4]. This experiment was also the first test of Newton's theory of gravitation between masses in the laboratory. It took place 111 years after the publication of Newton's Principia and 71 years after Newton's death, so none of Newton's calculations could use the value of G; instead he could only calculate a force relative to another force.
Newton's law of gravitation resembles Coulomb's law of electrical forces, which is used to calculate the magnitude of electrical force between two charged bodies. Both are inverse-square laws, in which force is inversely proportional to the square of the distance between the bodies. Coulomb's Law has the product of two charges in place of the product of the masses, and the electrostatic constant in place of the gravitational constant.
Newton's law has since been superseded by Einstein's theory of general relativity, but it continues to be used as an excellent approximation of the effects of gravity. Relativity is only required when there is a need for extreme precision, or when dealing with gravitation for extremely massive and dense objects.
Jump to: navigation, search
Classical mechanics
\mathbf{F} = \frac{\mathrm{d}}{\mathrm{d}t}(m \mathbf{v})
Newton's Second Law
History of classical mechanics · Timeline of classical mechanics
[show]Branches
Statics · Dynamics / Kinetics · Kinematics · Applied mechanics · Celestial mechanics · Continuum mechanics · Statistical mechanics
[show]Formulations
* Newtonian mechanics (Vectorial mechanics)
* Analytical mechanics:
o Lagrangian mechanics
o Hamiltonian mechanics
[show]Fundamental concepts
Space · Time · Velocity · Speed · Mass · Acceleration · Gravity · Force · Impulse · Torque / Moment / Couple · Momentum · Angular momentum · Inertia · Moment of inertia · Reference frame · Energy · Kinetic energy · Potential energy · Mechanical work · Virtual work · D'Alembert's principle
[show]Core topics
Rigid body · Rigid body dynamics · Euler's equations (rigid body dynamics) · Motion · Newton's laws of motion · Newton's law of universal gravitation · Equations of motion · Inertial frame of reference · Non-inertial reference frame · Rotating reference frame · Fictitious force · Linear motion · Mechanics of planar particle motion · Displacement (vector) · Relative velocity · Friction · Simple harmonic motion · Harmonic oscillator · Vibration · Damping · Damping ratio · Rotational motion · Circular motion · Uniform circular motion · Non-uniform circular motion · Centripetal force · Centrifugal force · Centrifugal force (rotating reference frame) · Reactive centrifugal force · Coriolis force · Pendulum · Rotational speed · Angular acceleration · Angular velocity · Angular frequency · Angular displacement
[show]Scientists
Galileo Galilei · Isaac Newton · Jeremiah Horrocks · Leonhard Euler · Jean le Rond d'Alembert · Alexis Clairaut · Joseph Louis Lagrange · Pierre-Simon Laplace · William Rowan Hamilton · Siméon-Denis Poisson
v · d · e
The mechanisms of Newton's law of universal gravitation; a point mass m1 attracts another point mass m2 by a force F2 which is proportional to the product of the two masses and inversely proportional to the square of the distance (r) between them. Regardless of masses or distance, the magnitudes of |F1| and |F2| will always be equal. G is the gravitational constant.
Newton's law of universal gravitation states that every massive particle in the universe attracts every other massive particle with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. (Separately it was shown that large spherically-symmetrical masses attract and are attracted as if all their mass were concentrated at their centers.) This is a general physical law derived from empirical observations by what Newton called induction.[1] It is a part of classical mechanics and was formulated in Newton's work Philosophiae Naturalis Principia Mathematica ("the Principia"), first published on 5 July 1687. (When Newton's book was presented in 1686 to the Royal Society, Robert Hooke made a claim that Newton had obtained the inverse square law from him – see History section below.) In modern language, the law states the following:
Every point mass attracts every single other point mass by a force pointing along the line intersecting both points. The force is directly proportional to the product of the two masses and inversely proportional to the square of the distance between the point masses:[2]
F = G \frac{m_1 m_2}{r^2}\ ,
where:
* F is the magnitude of the gravitational force between the two point masses,
* G is the gravitational constant,
* m1 is the mass of the first point mass,
* m2 is the mass of the second point mass, and
* r is the distance between the two point masses.
Assuming SI units, F is measured in newtons (N), m1 and m2 in kilograms (kg), r in meters (m), and the constant G is approximately equal to 6.674×10−11
N m2 kg−2.[3] The value of the constant G was first accurately determined from the results of the Cavendish experiment conducted by the British scientist Henry Cavendish in 1798, although Cavendish did not himself calculate a numerical value for G[4]. This experiment was also the first test of Newton's theory of gravitation between masses in the laboratory. It took place 111 years after the publication of Newton's Principia and 71 years after Newton's death, so none of Newton's calculations could use the value of G; instead he could only calculate a force relative to another force.
Newton's law of gravitation resembles Coulomb's law of electrical forces, which is used to calculate the magnitude of electrical force between two charged bodies. Both are inverse-square laws, in which force is inversely proportional to the square of the distance between the bodies. Coulomb's Law has the product of two charges in place of the product of the masses, and the electrostatic constant in place of the gravitational constant.
Newton's law has since been superseded by Einstein's theory of general relativity, but it continues to be used as an excellent approximation of the effects of gravity. Relativity is only required when there is a need for extreme precision, or when dealing with gravitation for extremely massive and dense objects.
Newton history
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In 1686, when the first book of Newton's 'Principia' was presented to the Royal Society, Robert Hooke claimed that Newton had from him the "notion" of "the rule of the decrease of Gravity, being reciprocally as the squares of the distances from the Center". At the same time (according to Edmond Halley's contemporary report) Hooke agreed that "the Demonstration of the Curves generated thereby" was wholly Newton's.[5]
In this way arose the question what, if anything, did Newton owe to Hooke? – a subject extensively discussed since that time, and on which some points still excite some controversy.
Robert Hooke published his ideas about the "System of the World" in the 1660s, when he read to the Royal Society on 21 March 1666 a paper "On gravity", "concerning the inflection of a direct motion into a curve by a supervening attractive principle", and he published them again in somewhat developed form in 1674, as an addition to "An Attempt to Prove the Motion of the Earth from Observations".[6] Hooke announced in 1674 that he planned to "explain a System of the World differing in many particulars from any yet known", based on three "Suppositions": that "all Coelestial Bodies whatsoever, have an attraction or gravitating power towards their own Centers" [and] "they do also attract all the other Coelestial Bodies that are within the sphere of their activity";[7] that "all bodies whatsoever that are put into a direct and simple motion, will so continue to move forward in a straight line, till they are by some other effectual powers deflected and bent..."; and that "these attractive powers are so much the more powerful in operating, by how much the nearer the body wrought upon is to their own Centers". Thus Hooke clearly postulated mutual attractions between the Sun and planets, in a way that increased with nearness to the attracting body, together with a principle of linear inertia.
Hooke's statements up to 1674 made no mention, however, that an inverse square law applies or might apply to these attractions. Hooke's gravitation was also not yet universal, though it approached universality more closely than previous hypotheses.[8] He also did not provide accompanying evidence or mathematical demonstration. On the latter two aspects, Hooke himself stated in 1674: "Now what these several degrees [of attraction] are I have not yet experimentally verified"; and as to his whole proposal: "This I only hint at present", "having my self many other things in hand which I would first compleat, and therefore cannot so well attend it" (i.e. "prosecuting this Inquiry").[6] It was later on, in writing on 6 January 1679|80 to Newton, that Hooke communicated his "supposition ... that the Attraction always is in a duplicate proportion to the Distance from the Center Reciprocall, and Consequently that the Velocity will be in a subduplicate proportion to the Attraction and Consequently as Kepler Supposes Reciprocall to the Distance."[9] (The inference about the velocity was incorrect.[10])
Hooke's correspondence of 1679-1680 with Newton mentioned not only this inverse square supposition for the decline of attraction with increasing distance, but also, in Hooke's opening letter to Newton, of 24 November 1679, an approach of "compounding the celestiall motions of the planetts of a direct motion by the tangent & an attractive motion towards the centrall body".[11]
A recent assessment (by Ofer Gal) about the early history of the inverse square law is that "by the late 1660s," the assumption of an "inverse proportion between gravity and the square of distance was rather common and had been advanced by a number of different people for different reasons".[12] (The same author does credit Hooke with a significant and even seminal contribution, but he treats Hooke's claim of priority on the inverse square point as uninteresting since several individuals besides Newton and Hooke had at least suggested it, and he points instead to the idea of "compounding the celestiall motions" and the conversion of Newton's thinking away from 'centrifugal' and towards 'centripetal' force as Hooke's significant contributions.)
Newton, faced in May 1686 with Hooke's claim on the inverse square law, denied that Hooke was to be credited as author of the idea, giving reasons. Among these, Newton recalled that the idea had been known to and discussed with Sir Christopher Wren previous to Hooke's 1679 letter.[13] Newton also pointed out and acknowledged prior work of others,[14] including Bullialdus,[15] (who suggested, but without demonstration, that there was an attractive force from the Sun in the inverse square proportion to the distance), and Borelli[16] (who suggested, also without demonstration, that there was a centrifugal tendency in counterbalance with a gravitational attraction towards the Sun so as to make the planets move in ellipses). D T Whiteside has described the contribution to Newton's thinking that came from Borelli's book (a copy of which was in Newton's library at his death).[17]
Newton also firmly claimed that even if it had happened that he had first heard of the inverse square proportion from Hooke, which it had not, he would still have some rights to it in view of his demonstrations of its accuracy, because Hooke, without evidence in favour of the supposition, could only guess that it was approximately valid "at great distances from the center": According to Newton, writing while the 'Principia' was still at pre-publication stage, there were so many a-priori reasons to doubt the accuracy of the inverse-square law (especially close to an attracting sphere) that "without my" (Newton's) "Demonstrations, to which Mr Hook is yet a stranger, it cannot be beleived by a judicious Philosopher to be any where accurate."[18] (This remark refers among other things to Newton's finding, supported by mathematical demonstration, that if the inverse square law applies to tiny particles, then even a large spherically symmetrical mass also attracts masses external to its surface, even close up, exactly as if all its own mass were concentrated at its center. Thus Newton gave a justification, otherwise lacking, for applying the inverse square law to large spherical planetary masses as if they were tiny particles.[19] In addition, Newton had formulated in Propositions 43-45 of Book 1,[20] and associated sections of Book 3, a sensitive test of the accuracy of the inverse square law, in which he showed that only where the law of force is accurately as the inverse square of the distance will the directions of orientation of the planets' orbital ellipses stay constant as they are observed to do apart from small effects attributable to inter-planetary perturbations.)
In regard to evidence that still survives of the earlier history, manuscripts written by Newton in the 1660s show that Newton himself had arrived by 1669 at proofs that in a circular case of planetary motion, 'endeavour to recede' (centrifugal force by another name) had an inverse-square relation with distance from the center.[21] At that time, Newton was thinking and writing in terms of 'endeavour to recede' from a center, i.e. what was later called centrifugal force. After his 1679-1680 correspondence with Hooke, Newton adopted the language of inward or centripetal force. According to Newton scholar J Bruce Brackenridge, although much has been made of the change in language and difference of point of view, as between centrifugal or centripetal forces, the actual computations and proofs remained the same either way. They also involved the combination of tangential and radial displacements, which Newton was making in the 1660s. The lesson offered by Hooke to Newton here, although significant, was one of perspective and did not change the analysis.[22] This background shows there was basis for Newton to deny deriving the inverse square law from Hooke.
Newton also clearly expressed the concept of linear inertia long before his correspondence with Hooke: for this Newton was indebted to Descartes' work published in 1644.[23]
On the other hand, Newton did accept and acknowledge, in all editions of the 'Principia', that Hooke (but not exclusively Hooke) had separately appreciated the inverse square law in the solar system. Newton acknowledged Wren, Hooke and Halley in this connection in the Scholium to Proposition 4 in Book 1.[24] Newton also acknowledged to Halley that his correspondence with Hooke in 1679-80 had reawakened his dormant interest in astronomical matters, but that did not mean, according to Newton, that Hooke had told Newton anything new or original: "yet am I not beholden to him for any light into that business but only for the diversion he gave me from my other studies to think on these things & for his dogmaticalness in writing as if he had found the motion in the Ellipsis, which inclined me to try it ...".[14])
Since the time of Newton and Hooke, scholarly discussion has also touched on the question whether Hooke's 1679 mention of 'compounding the motions' gave Newton with something new and valuable, even though that was not a claim actually voiced by Hooke at the time. As described above, Newton's manuscripts of the 1660s do show him actually combining tangential motion with the effects of radially directed force or endeavour, for example in his derivation of the inverse square relation for the circular case. They also show Newton clearly expressing the concept of linear inertia—for which he was indebted to Descartes' work published 1644 (as Hooke probably was).[23] These matters do not appear to have been learned by Newton from Hooke.
Nevertheless, a number of authors have had more to say about what Newton gained from Hooke and some aspects remain controversial.[25] The fact that most of Hooke's private papers had been destroyed or disappeared does not help to establish the truth.
Newton's role in relation to the inverse square law was not as it has sometimes been represented, he did not claim to think it up as a bare idea. What Newton did was to show how the inverse-square law of attraction had many necessary mathematical connections with observable features of the motions of bodies in the solar system; and that they were related in such a way that the observational evidence and the mathematical demonstrations, taken together, gave reason to believe that the inverse square law was not just approximately true but exactly true (to the accuracy achievable in Newton's time and for about two centuries afterwards – and with some loose ends of points that could not yet be certainly examined, where the implications of the theory had not yet been adequately identified or calculated).[26][27]
In the light of the background described above, it becomes understandable how, about thirty years after Newton's death in 1727, Alexis Clairaut, a mathematical astronomer eminent in his own right in the field of gravitational studies, wrote after reviewing what Hooke published, that "One must not think that this idea ... of Hooke diminishes Newton's glory"; and that "the example of Hooke" serves "to show what a distance there is between a truth that is glimpsed and a truth that is demonstrated"
This section of the article is too long to read comfortably, and needs subsections. Please format the article according to the guidelines laid out at Wikipedia:Manual of Style (headings) (June 2010)
In 1686, when the first book of Newton's 'Principia' was presented to the Royal Society, Robert Hooke claimed that Newton had from him the "notion" of "the rule of the decrease of Gravity, being reciprocally as the squares of the distances from the Center". At the same time (according to Edmond Halley's contemporary report) Hooke agreed that "the Demonstration of the Curves generated thereby" was wholly Newton's.[5]
In this way arose the question what, if anything, did Newton owe to Hooke? – a subject extensively discussed since that time, and on which some points still excite some controversy.
Robert Hooke published his ideas about the "System of the World" in the 1660s, when he read to the Royal Society on 21 March 1666 a paper "On gravity", "concerning the inflection of a direct motion into a curve by a supervening attractive principle", and he published them again in somewhat developed form in 1674, as an addition to "An Attempt to Prove the Motion of the Earth from Observations".[6] Hooke announced in 1674 that he planned to "explain a System of the World differing in many particulars from any yet known", based on three "Suppositions": that "all Coelestial Bodies whatsoever, have an attraction or gravitating power towards their own Centers" [and] "they do also attract all the other Coelestial Bodies that are within the sphere of their activity";[7] that "all bodies whatsoever that are put into a direct and simple motion, will so continue to move forward in a straight line, till they are by some other effectual powers deflected and bent..."; and that "these attractive powers are so much the more powerful in operating, by how much the nearer the body wrought upon is to their own Centers". Thus Hooke clearly postulated mutual attractions between the Sun and planets, in a way that increased with nearness to the attracting body, together with a principle of linear inertia.
Hooke's statements up to 1674 made no mention, however, that an inverse square law applies or might apply to these attractions. Hooke's gravitation was also not yet universal, though it approached universality more closely than previous hypotheses.[8] He also did not provide accompanying evidence or mathematical demonstration. On the latter two aspects, Hooke himself stated in 1674: "Now what these several degrees [of attraction] are I have not yet experimentally verified"; and as to his whole proposal: "This I only hint at present", "having my self many other things in hand which I would first compleat, and therefore cannot so well attend it" (i.e. "prosecuting this Inquiry").[6] It was later on, in writing on 6 January 1679|80 to Newton, that Hooke communicated his "supposition ... that the Attraction always is in a duplicate proportion to the Distance from the Center Reciprocall, and Consequently that the Velocity will be in a subduplicate proportion to the Attraction and Consequently as Kepler Supposes Reciprocall to the Distance."[9] (The inference about the velocity was incorrect.[10])
Hooke's correspondence of 1679-1680 with Newton mentioned not only this inverse square supposition for the decline of attraction with increasing distance, but also, in Hooke's opening letter to Newton, of 24 November 1679, an approach of "compounding the celestiall motions of the planetts of a direct motion by the tangent & an attractive motion towards the centrall body".[11]
A recent assessment (by Ofer Gal) about the early history of the inverse square law is that "by the late 1660s," the assumption of an "inverse proportion between gravity and the square of distance was rather common and had been advanced by a number of different people for different reasons".[12] (The same author does credit Hooke with a significant and even seminal contribution, but he treats Hooke's claim of priority on the inverse square point as uninteresting since several individuals besides Newton and Hooke had at least suggested it, and he points instead to the idea of "compounding the celestiall motions" and the conversion of Newton's thinking away from 'centrifugal' and towards 'centripetal' force as Hooke's significant contributions.)
Newton, faced in May 1686 with Hooke's claim on the inverse square law, denied that Hooke was to be credited as author of the idea, giving reasons. Among these, Newton recalled that the idea had been known to and discussed with Sir Christopher Wren previous to Hooke's 1679 letter.[13] Newton also pointed out and acknowledged prior work of others,[14] including Bullialdus,[15] (who suggested, but without demonstration, that there was an attractive force from the Sun in the inverse square proportion to the distance), and Borelli[16] (who suggested, also without demonstration, that there was a centrifugal tendency in counterbalance with a gravitational attraction towards the Sun so as to make the planets move in ellipses). D T Whiteside has described the contribution to Newton's thinking that came from Borelli's book (a copy of which was in Newton's library at his death).[17]
Newton also firmly claimed that even if it had happened that he had first heard of the inverse square proportion from Hooke, which it had not, he would still have some rights to it in view of his demonstrations of its accuracy, because Hooke, without evidence in favour of the supposition, could only guess that it was approximately valid "at great distances from the center": According to Newton, writing while the 'Principia' was still at pre-publication stage, there were so many a-priori reasons to doubt the accuracy of the inverse-square law (especially close to an attracting sphere) that "without my" (Newton's) "Demonstrations, to which Mr Hook is yet a stranger, it cannot be beleived by a judicious Philosopher to be any where accurate."[18] (This remark refers among other things to Newton's finding, supported by mathematical demonstration, that if the inverse square law applies to tiny particles, then even a large spherically symmetrical mass also attracts masses external to its surface, even close up, exactly as if all its own mass were concentrated at its center. Thus Newton gave a justification, otherwise lacking, for applying the inverse square law to large spherical planetary masses as if they were tiny particles.[19] In addition, Newton had formulated in Propositions 43-45 of Book 1,[20] and associated sections of Book 3, a sensitive test of the accuracy of the inverse square law, in which he showed that only where the law of force is accurately as the inverse square of the distance will the directions of orientation of the planets' orbital ellipses stay constant as they are observed to do apart from small effects attributable to inter-planetary perturbations.)
In regard to evidence that still survives of the earlier history, manuscripts written by Newton in the 1660s show that Newton himself had arrived by 1669 at proofs that in a circular case of planetary motion, 'endeavour to recede' (centrifugal force by another name) had an inverse-square relation with distance from the center.[21] At that time, Newton was thinking and writing in terms of 'endeavour to recede' from a center, i.e. what was later called centrifugal force. After his 1679-1680 correspondence with Hooke, Newton adopted the language of inward or centripetal force. According to Newton scholar J Bruce Brackenridge, although much has been made of the change in language and difference of point of view, as between centrifugal or centripetal forces, the actual computations and proofs remained the same either way. They also involved the combination of tangential and radial displacements, which Newton was making in the 1660s. The lesson offered by Hooke to Newton here, although significant, was one of perspective and did not change the analysis.[22] This background shows there was basis for Newton to deny deriving the inverse square law from Hooke.
Newton also clearly expressed the concept of linear inertia long before his correspondence with Hooke: for this Newton was indebted to Descartes' work published in 1644.[23]
On the other hand, Newton did accept and acknowledge, in all editions of the 'Principia', that Hooke (but not exclusively Hooke) had separately appreciated the inverse square law in the solar system. Newton acknowledged Wren, Hooke and Halley in this connection in the Scholium to Proposition 4 in Book 1.[24] Newton also acknowledged to Halley that his correspondence with Hooke in 1679-80 had reawakened his dormant interest in astronomical matters, but that did not mean, according to Newton, that Hooke had told Newton anything new or original: "yet am I not beholden to him for any light into that business but only for the diversion he gave me from my other studies to think on these things & for his dogmaticalness in writing as if he had found the motion in the Ellipsis, which inclined me to try it ...".[14])
Since the time of Newton and Hooke, scholarly discussion has also touched on the question whether Hooke's 1679 mention of 'compounding the motions' gave Newton with something new and valuable, even though that was not a claim actually voiced by Hooke at the time. As described above, Newton's manuscripts of the 1660s do show him actually combining tangential motion with the effects of radially directed force or endeavour, for example in his derivation of the inverse square relation for the circular case. They also show Newton clearly expressing the concept of linear inertia—for which he was indebted to Descartes' work published 1644 (as Hooke probably was).[23] These matters do not appear to have been learned by Newton from Hooke.
Nevertheless, a number of authors have had more to say about what Newton gained from Hooke and some aspects remain controversial.[25] The fact that most of Hooke's private papers had been destroyed or disappeared does not help to establish the truth.
Newton's role in relation to the inverse square law was not as it has sometimes been represented, he did not claim to think it up as a bare idea. What Newton did was to show how the inverse-square law of attraction had many necessary mathematical connections with observable features of the motions of bodies in the solar system; and that they were related in such a way that the observational evidence and the mathematical demonstrations, taken together, gave reason to believe that the inverse square law was not just approximately true but exactly true (to the accuracy achievable in Newton's time and for about two centuries afterwards – and with some loose ends of points that could not yet be certainly examined, where the implications of the theory had not yet been adequately identified or calculated).[26][27]
In the light of the background described above, it becomes understandable how, about thirty years after Newton's death in 1727, Alexis Clairaut, a mathematical astronomer eminent in his own right in the field of gravitational studies, wrote after reviewing what Hooke published, that "One must not think that this idea ... of Hooke diminishes Newton's glory"; and that "the example of Hooke" serves "to show what a distance there is between a truth that is glimpsed and a truth that is demonstrated"
Newton
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In 1686, when the first book of Newton's 'Principia' was presented to the Royal Society, Robert Hooke claimed that Newton had from him the "notion" of "the rule of the decrease of Gravity, being reciprocally as the squares of the distances from the Center". At the same time (according to Edmond Halley's contemporary report) Hooke agreed that "the Demonstration of the Curves generated thereby" was wholly Newton's.[5]
In this way arose the question what, if anything, did Newton owe to Hooke? – a subject extensively discussed since that time, and on which some points still excite some controversy.
Robert Hooke published his ideas about the "System of the World" in the 1660s, when he read to the Royal Society on 21 March 1666 a paper "On gravity", "concerning the inflection of a direct motion into a curve by a supervening attractive principle", and he published them again in somewhat developed form in 1674, as an addition to "An Attempt to Prove the Motion of the Earth from Observations".[6] Hooke announced in 1674 that he planned to "explain a System of the World differing in many particulars from any yet known", based on three "Suppositions": that "all Coelestial Bodies whatsoever, have an attraction or gravitating power towards their own Centers" [and] "they do also attract all the other Coelestial Bodies that are within the sphere of their activity";[7] that "all bodies whatsoever that are put into a direct and simple motion, will so continue to move forward in a straight line, till they are by some other effectual powers deflected and bent..."; and that "these attractive powers are so much the more powerful in operating, by how much the nearer the body wrought upon is to their own Centers". Thus Hooke clearly postulated mutual attractions between the Sun and planets, in a way that increased with nearness to the attracting body, together with a principle of linear inertia.
Hooke's statements up to 1674 made no mention, however, that an inverse square law applies or might apply to these attractions. Hooke's gravitation was also not yet universal, though it approached universality more closely than previous hypotheses.[8] He also did not provide accompanying evidence or mathematical demonstration. On the latter two aspects, Hooke himself stated in 1674: "Now what these several degrees [of attraction] are I have not yet experimentally verified"; and as to his whole proposal: "This I only hint at present", "having my self many other things in hand which I would first compleat, and therefore cannot so well attend it" (i.e. "prosecuting this Inquiry").[6] It was later on, in writing on 6 January 1679|80 to Newton, that Hooke communicated his "supposition ... that the Attraction always is in a duplicate proportion to the Distance from the Center Reciprocall, and Consequently that the Velocity will be in a subduplicate proportion to the Attraction and Consequently as Kepler Supposes Reciprocall to the Distance."[9] (The inference about the velocity was incorrect.[10])
Hooke's correspondence of 1679-1680 with Newton mentioned not only this inverse square supposition for the decline of attraction with increasing distance, but also, in Hooke's opening letter to Newton, of 24 November 1679, an approach of "compounding the celestiall motions of the planetts of a direct motion by the tangent & an attractive motion towards the centrall body".[11]
A recent assessment (by Ofer Gal) about the early history of the inverse square law is that "by the late 1660s," the assumption of an "inverse proportion between gravity and the square of distance was rather common and had been advanced by a number of different people for different reasons".[12] (The same author does credit Hooke with a significant and even seminal contribution, but he treats Hooke's claim of priority on the inverse square point as uninteresting since several individuals besides Newton and Hooke had at least suggested it, and he points instead to the idea of "compounding the celestiall motions" and the conversion of Newton's thinking away from 'centrifugal' and towards 'centripetal' force as Hooke's significant contributions.)
Newton, faced in May 1686 with Hooke's claim on the inverse square law, denied that Hooke was to be credited as author of the idea, giving reasons. Among these, Newton recalled that the idea had been known to and discussed with Sir Christopher Wren previous to Hooke's 1679 letter.[13] Newton also pointed out and acknowledged prior work of others,[14] including Bullialdus,[15] (who suggested, but without demonstration, that there was an attractive force from the Sun in the inverse square proportion to the distance), and Borelli[16] (who suggested, also without demonstration, that there was a centrifugal tendency in counterbalance with a gravitational attraction towards the Sun so as to make the planets move in ellipses). D T Whiteside has described the contribution to Newton's thinking that came from Borelli's book (a copy of which was in Newton's library at his death).[17]
Newton also firmly claimed that even if it had happened that he had first heard of the inverse square proportion from Hooke, which it had not, he would still have some rights to it in view of his demonstrations of its accuracy, because Hooke, without evidence in favour of the supposition, could only guess that it was approximately valid "at great distances from the center": According to Newton, writing while the 'Principia' was still at pre-publication stage, there were so many a-priori reasons to doubt the accuracy of the inverse-square law (especially close to an attracting sphere) that "without my" (Newton's) "Demonstrations, to which Mr Hook is yet a stranger, it cannot be beleived by a judicious Philosopher to be any where accurate."[18] (This remark refers among other things to Newton's finding, supported by mathematical demonstration, that if the inverse square law applies to tiny particles, then even a large spherically symmetrical mass also attracts masses external to its surface, even close up, exactly as if all its own mass were concentrated at its center. Thus Newton gave a justification, otherwise lacking, for applying the inverse square law to large spherical planetary masses as if they were tiny particles.[19] In addition, Newton had formulated in Propositions 43-45 of Book 1,[20] and associated sections of Book 3, a sensitive test of the accuracy of the inverse square law, in which he showed that only where the law of force is accurately as the inverse square of the distance will the directions of orientation of the planets' orbital ellipses stay constant as they are observed to do apart from small effects attributable to inter-planetary perturbations.)
In regard to evidence that still survives of the earlier history, manuscripts written by Newton in the 1660s show that Newton himself had arrived by 1669 at proofs that in a circular case of planetary motion, 'endeavour to recede' (centrifugal force by another name) had an inverse-square relation with distance from the center.[21] At that time, Newton was thinking and writing in terms of 'endeavour to recede' from a center, i.e. what was later called centrifugal force. After his 1679-1680 correspondence with Hooke, Newton adopted the language of inward or centripetal force. According to Newton scholar J Bruce Brackenridge, although much has been made of the change in language and difference of point of view, as between centrifugal or centripetal forces, the actual computations and proofs remained the same either way. They also involved the combination of tangential and radial displacements, which Newton was making in the 1660s. The lesson offered by Hooke to Newton here, although significant, was one of perspective and did not change the analysis.[22] This background shows there was basis for Newton to deny deriving the inverse square law from Hooke.
Newton also clearly expressed the concept of linear inertia long before his correspondence with Hooke: for this Newton was indebted to Descartes' work published in 1644.[23]
On the other hand, Newton did accept and acknowledge, in all editions of the 'Principia', that Hooke (but not exclusively Hooke) had separately appreciated the inverse square law in the solar system. Newton acknowledged Wren, Hooke and Halley in this connection in the Scholium to Proposition 4 in Book 1.[24] Newton also acknowledged to Halley that his correspondence with Hooke in 1679-80 had reawakened his dormant interest in astronomical matters, but that did not mean, according to Newton, that Hooke had told Newton anything new or original: "yet am I not beholden to him for any light into that business but only for the diversion he gave me from my other studies to think on these things & for his dogmaticalness in writing as if he had found the motion in the Ellipsis, which inclined me to try it ...".[14])
Since the time of Newton and Hooke, scholarly discussion has also touched on the question whether Hooke's 1679 mention of 'compounding the motions' gave Newton with something new and valuable, even though that was not a claim actually voiced by Hooke at the time. As described above, Newton's manuscripts of the 1660s do show him actually combining tangential motion with the effects of radially directed force or endeavour, for example in his derivation of the inverse square relation for the circular case. They also show Newton clearly expressing the concept of linear inertia—for which he was indebted to Descartes' work published 1644 (as Hooke probably was).[23] These matters do not appear to have been learned by Newton from Hooke.
Nevertheless, a number of authors have had more to say about what Newton gained from Hooke and some aspects remain controversial.[25] The fact that most of Hooke's private papers had been destroyed or disappeared does not help to establish the truth.
Newton's role in relation to the inverse square law was not as it has sometimes been represented, he did not claim to think it up as a bare idea. What Newton did was to show how the inverse-square law of attraction had many necessary mathematical connections with observable features of the motions of bodies in the solar system; and that they were related in such a way that the observational evidence and the mathematical demonstrations, taken together, gave reason to believe that the inverse square law was not just approximately true but exactly true (to the accuracy achievable in Newton's time and for about two centuries afterwards – and with some loose ends of points that could not yet be certainly examined, where the implications of the theory had not yet been adequately identified or calculated).[26][27]
In the light of the background described above, it becomes understandable how, about thirty years after Newton's death in 1727, Alexis Clairaut, a mathematical astronomer eminent in his own right in the field of gravitational studies, wrote after reviewing what Hooke published, that "One must not think that this idea ... of Hooke diminishes Newton's glory"; and that "the example of Hooke" serves "to show what a distance there is between a truth that is glimpsed and a truth that is demonstrated"
This section of the article is too long to read comfortably, and needs subsections. Please format the article according to the guidelines laid out at Wikipedia:Manual of Style (headings) (June 2010)
In 1686, when the first book of Newton's 'Principia' was presented to the Royal Society, Robert Hooke claimed that Newton had from him the "notion" of "the rule of the decrease of Gravity, being reciprocally as the squares of the distances from the Center". At the same time (according to Edmond Halley's contemporary report) Hooke agreed that "the Demonstration of the Curves generated thereby" was wholly Newton's.[5]
In this way arose the question what, if anything, did Newton owe to Hooke? – a subject extensively discussed since that time, and on which some points still excite some controversy.
Robert Hooke published his ideas about the "System of the World" in the 1660s, when he read to the Royal Society on 21 March 1666 a paper "On gravity", "concerning the inflection of a direct motion into a curve by a supervening attractive principle", and he published them again in somewhat developed form in 1674, as an addition to "An Attempt to Prove the Motion of the Earth from Observations".[6] Hooke announced in 1674 that he planned to "explain a System of the World differing in many particulars from any yet known", based on three "Suppositions": that "all Coelestial Bodies whatsoever, have an attraction or gravitating power towards their own Centers" [and] "they do also attract all the other Coelestial Bodies that are within the sphere of their activity";[7] that "all bodies whatsoever that are put into a direct and simple motion, will so continue to move forward in a straight line, till they are by some other effectual powers deflected and bent..."; and that "these attractive powers are so much the more powerful in operating, by how much the nearer the body wrought upon is to their own Centers". Thus Hooke clearly postulated mutual attractions between the Sun and planets, in a way that increased with nearness to the attracting body, together with a principle of linear inertia.
Hooke's statements up to 1674 made no mention, however, that an inverse square law applies or might apply to these attractions. Hooke's gravitation was also not yet universal, though it approached universality more closely than previous hypotheses.[8] He also did not provide accompanying evidence or mathematical demonstration. On the latter two aspects, Hooke himself stated in 1674: "Now what these several degrees [of attraction] are I have not yet experimentally verified"; and as to his whole proposal: "This I only hint at present", "having my self many other things in hand which I would first compleat, and therefore cannot so well attend it" (i.e. "prosecuting this Inquiry").[6] It was later on, in writing on 6 January 1679|80 to Newton, that Hooke communicated his "supposition ... that the Attraction always is in a duplicate proportion to the Distance from the Center Reciprocall, and Consequently that the Velocity will be in a subduplicate proportion to the Attraction and Consequently as Kepler Supposes Reciprocall to the Distance."[9] (The inference about the velocity was incorrect.[10])
Hooke's correspondence of 1679-1680 with Newton mentioned not only this inverse square supposition for the decline of attraction with increasing distance, but also, in Hooke's opening letter to Newton, of 24 November 1679, an approach of "compounding the celestiall motions of the planetts of a direct motion by the tangent & an attractive motion towards the centrall body".[11]
A recent assessment (by Ofer Gal) about the early history of the inverse square law is that "by the late 1660s," the assumption of an "inverse proportion between gravity and the square of distance was rather common and had been advanced by a number of different people for different reasons".[12] (The same author does credit Hooke with a significant and even seminal contribution, but he treats Hooke's claim of priority on the inverse square point as uninteresting since several individuals besides Newton and Hooke had at least suggested it, and he points instead to the idea of "compounding the celestiall motions" and the conversion of Newton's thinking away from 'centrifugal' and towards 'centripetal' force as Hooke's significant contributions.)
Newton, faced in May 1686 with Hooke's claim on the inverse square law, denied that Hooke was to be credited as author of the idea, giving reasons. Among these, Newton recalled that the idea had been known to and discussed with Sir Christopher Wren previous to Hooke's 1679 letter.[13] Newton also pointed out and acknowledged prior work of others,[14] including Bullialdus,[15] (who suggested, but without demonstration, that there was an attractive force from the Sun in the inverse square proportion to the distance), and Borelli[16] (who suggested, also without demonstration, that there was a centrifugal tendency in counterbalance with a gravitational attraction towards the Sun so as to make the planets move in ellipses). D T Whiteside has described the contribution to Newton's thinking that came from Borelli's book (a copy of which was in Newton's library at his death).[17]
Newton also firmly claimed that even if it had happened that he had first heard of the inverse square proportion from Hooke, which it had not, he would still have some rights to it in view of his demonstrations of its accuracy, because Hooke, without evidence in favour of the supposition, could only guess that it was approximately valid "at great distances from the center": According to Newton, writing while the 'Principia' was still at pre-publication stage, there were so many a-priori reasons to doubt the accuracy of the inverse-square law (especially close to an attracting sphere) that "without my" (Newton's) "Demonstrations, to which Mr Hook is yet a stranger, it cannot be beleived by a judicious Philosopher to be any where accurate."[18] (This remark refers among other things to Newton's finding, supported by mathematical demonstration, that if the inverse square law applies to tiny particles, then even a large spherically symmetrical mass also attracts masses external to its surface, even close up, exactly as if all its own mass were concentrated at its center. Thus Newton gave a justification, otherwise lacking, for applying the inverse square law to large spherical planetary masses as if they were tiny particles.[19] In addition, Newton had formulated in Propositions 43-45 of Book 1,[20] and associated sections of Book 3, a sensitive test of the accuracy of the inverse square law, in which he showed that only where the law of force is accurately as the inverse square of the distance will the directions of orientation of the planets' orbital ellipses stay constant as they are observed to do apart from small effects attributable to inter-planetary perturbations.)
In regard to evidence that still survives of the earlier history, manuscripts written by Newton in the 1660s show that Newton himself had arrived by 1669 at proofs that in a circular case of planetary motion, 'endeavour to recede' (centrifugal force by another name) had an inverse-square relation with distance from the center.[21] At that time, Newton was thinking and writing in terms of 'endeavour to recede' from a center, i.e. what was later called centrifugal force. After his 1679-1680 correspondence with Hooke, Newton adopted the language of inward or centripetal force. According to Newton scholar J Bruce Brackenridge, although much has been made of the change in language and difference of point of view, as between centrifugal or centripetal forces, the actual computations and proofs remained the same either way. They also involved the combination of tangential and radial displacements, which Newton was making in the 1660s. The lesson offered by Hooke to Newton here, although significant, was one of perspective and did not change the analysis.[22] This background shows there was basis for Newton to deny deriving the inverse square law from Hooke.
Newton also clearly expressed the concept of linear inertia long before his correspondence with Hooke: for this Newton was indebted to Descartes' work published in 1644.[23]
On the other hand, Newton did accept and acknowledge, in all editions of the 'Principia', that Hooke (but not exclusively Hooke) had separately appreciated the inverse square law in the solar system. Newton acknowledged Wren, Hooke and Halley in this connection in the Scholium to Proposition 4 in Book 1.[24] Newton also acknowledged to Halley that his correspondence with Hooke in 1679-80 had reawakened his dormant interest in astronomical matters, but that did not mean, according to Newton, that Hooke had told Newton anything new or original: "yet am I not beholden to him for any light into that business but only for the diversion he gave me from my other studies to think on these things & for his dogmaticalness in writing as if he had found the motion in the Ellipsis, which inclined me to try it ...".[14])
Since the time of Newton and Hooke, scholarly discussion has also touched on the question whether Hooke's 1679 mention of 'compounding the motions' gave Newton with something new and valuable, even though that was not a claim actually voiced by Hooke at the time. As described above, Newton's manuscripts of the 1660s do show him actually combining tangential motion with the effects of radially directed force or endeavour, for example in his derivation of the inverse square relation for the circular case. They also show Newton clearly expressing the concept of linear inertia—for which he was indebted to Descartes' work published 1644 (as Hooke probably was).[23] These matters do not appear to have been learned by Newton from Hooke.
Nevertheless, a number of authors have had more to say about what Newton gained from Hooke and some aspects remain controversial.[25] The fact that most of Hooke's private papers had been destroyed or disappeared does not help to establish the truth.
Newton's role in relation to the inverse square law was not as it has sometimes been represented, he did not claim to think it up as a bare idea. What Newton did was to show how the inverse-square law of attraction had many necessary mathematical connections with observable features of the motions of bodies in the solar system; and that they were related in such a way that the observational evidence and the mathematical demonstrations, taken together, gave reason to believe that the inverse square law was not just approximately true but exactly true (to the accuracy achievable in Newton's time and for about two centuries afterwards – and with some loose ends of points that could not yet be certainly examined, where the implications of the theory had not yet been adequately identified or calculated).[26][27]
In the light of the background described above, it becomes understandable how, about thirty years after Newton's death in 1727, Alexis Clairaut, a mathematical astronomer eminent in his own right in the field of gravitational studies, wrote after reviewing what Hooke published, that "One must not think that this idea ... of Hooke diminishes Newton's glory"; and that "the example of Hooke" serves "to show what a distance there is between a truth that is glimpsed and a truth that is demonstrated"
philoshopy of science
The philosophy of science seeks to understand the nature and justification of scientific knowledge. It has proven difficult to provide a definitive account of scientific method that can decisively serve to distinguish science from non-science. Thus there are legitimate arguments about exactly where the borders are, which is known as the problem of demarcation. There is nonetheless a set of core precepts that have broad consensus among published philosophers of science and within the scientific community at large. For example, it is universally agreed that scientific hypotheses and theories must be capable of being independently tested and verified by other scientists in order to become accepted by the scientific community.
There are different schools of thought in the philosophy of scientific method. The most popular position is empirism, which claims that knowledge is created by a process involving observation and that hence scientific theories are the result of generalizations from observation. Empirism is generally held together with inductivism and positivism, which try to explain the way in which general theories can be justified by the finite number of observations humans can do and the hence finite amount of empirical evidence available to confirm scientific theories that make an infinite number of predictions that do not and cannot deductively follow from the evidence. It has been a long running matter of philosophical debate whether such positions require metaphysical assumptions about the structure of the world that themselves cannot be justified in a scientific way, and whether that poses a problem for science or not. Biologist Stephen J. Gould, for example, maintained that 1) uniformity of law and 2) uniformity of processes across time and space must first be assumed before you can proceed as a scientist doing science. Gould summarized this view as follows:
"The assumption of spatial and temporal invariance of natural laws is by no means unique to geology since it amounts to a warrant for inductive inference which, as Bacon showed nearly four hundred years ago, is the basic mode of reasoning in empirical science. Without assuming this spatial and temporal invariance, we have no basis for extrapolating from the known to the unknown and, therefore, no way of reaching general conclusions from a finite number of observations. (Since the assumption is itself vindicated by induction, it can in no way “prove” the validity of induction - an endeavor virtually abandoned after Hume demonstrated its futility two centuries ago)."[51]
Empirism holds that the landmark of scientific theories is their verifiability by induction from evidence.
Emprism has stood in contrast to rationalism, the opposing position which holds that knowledge is created by the human intellect, not by observation. The most recent and most sophisticated version of rationalism is critical rationalism, which attempts to acknowledge the fact that a connection exists between observation and theories, but rejects the way that empirism claims the nature of this connection to be. More specifically, critical rationalism claims that theories are not generated by observation, but the other way around, observation is made in the light of theories—it is "theory-laden" and never neutral—and that the only way a theory can be affected by observation is when comes in conflict with observation. In this view, there is no induction, only deduction with the key being the modus tollens. Critical rationalism acordingly proposes falsifiability as the landmark of empirical theories and falsification as the empirical method. It argues for the ability of science to increase the scope of testable knowledge, but at the same time against its authority, by emphasizing its inherent fallibility. It proposes that science should be content with the rational elimination of errors in its theories, not in seeking for their verification (such as claiming certain or probable proof or disproof; both the proposal and falsification of a theory are only of methodological, conjectural, and tentative character in critical rationalism).[52] This position, first brought forward by austrian-british philosopher Karl Popper, stands in sharp opposition to the prevalent popular as well as academic views on epistemology and the philosophy of science. It controversially implies that evidence[53] and scientific method do not actually exist.[54] Popper held that there is only one method, and that this method is universal, not in any way specific to science: The negative method of trial and error. It covers not only all products of the human mind, including science, mathematics, philosophy, art and so on, but also the evolution of life.[55] Popper especially questioned those positions that make a difference between natural and social sciences and criticized the prevalent philosophy of the social sciences as scientistic, as a mere imitation of the actual practice in the natural sciences. In this context, he contributed to the Positivism dispute, a philosophical dispute between Critical rationalism (Popper, Albert) and the Frankfurt School (Adorno, Habermas) about the methodology of the social sciences.[56] In contrast to positivism, which argues that science makes predictions that are guaranteed by evidence or at least made highly probable, or made more probable than can be achieved by other methods, Popper held the exact opposite to be true: Scientific theories are good because they are almost certainly false, which is the same as saying very improbable or easily falsifiable – yet cannot be successfully falsified (which, according to Popper, is emphatically not saying that they are in any way likely not to be falsified in the next instant, any time in the future, or over the long run). Popper, together with students William W. Bartley and David Miller, also questioned the classical theory of rationality for which rational knowledge in general, and scientific knowledge in particular stands out as knowledge that can be justified in a way that other claims cannot be justified (justified by evidence, by verification, by high probability). Popper criticized the very concept of justification (see justificationism) and argued that the only purpose of rationality is to eliminate false ideas by criticism (for non-empirical claims) and falsification (for empirical claims). He held that rationality has no way of justifying or sanctioning ideas. Popper, Bartley and Miller also argued against limits of rationality, especially against seeing falsifiability as a limit of rationality rather than merlely a limit of observability.
Another position, Instrumentalism, colloquially termed "shut up and calculate", rejects the concept of truth and emphasizes merely the utility of theories as instruments for explaining and predicting phenomena.[57] It essentially claims that scientific theories are black boxes with only their input (initial conditions) and output (predictions) being relevant. Consequences, notions and logical structure of the theories are claimed to be something that should simply be ignored and that scientists shouldn't make a fuss about (see interpretations of quantum mechanics).
A position often cited in political debates to conquer controverial views like creationism that purport to be scientific is methodological naturalism. It maintains that scientific investigation must adhere to empirical study and independent verification as a process for properly developing and evaluating natural explanations for observable phenomena.[58] Methodological naturalism, therefore, rejects supernatural explanations, arguments from authority and biased observational studies.
There are different schools of thought in the philosophy of scientific method. The most popular position is empirism, which claims that knowledge is created by a process involving observation and that hence scientific theories are the result of generalizations from observation. Empirism is generally held together with inductivism and positivism, which try to explain the way in which general theories can be justified by the finite number of observations humans can do and the hence finite amount of empirical evidence available to confirm scientific theories that make an infinite number of predictions that do not and cannot deductively follow from the evidence. It has been a long running matter of philosophical debate whether such positions require metaphysical assumptions about the structure of the world that themselves cannot be justified in a scientific way, and whether that poses a problem for science or not. Biologist Stephen J. Gould, for example, maintained that 1) uniformity of law and 2) uniformity of processes across time and space must first be assumed before you can proceed as a scientist doing science. Gould summarized this view as follows:
"The assumption of spatial and temporal invariance of natural laws is by no means unique to geology since it amounts to a warrant for inductive inference which, as Bacon showed nearly four hundred years ago, is the basic mode of reasoning in empirical science. Without assuming this spatial and temporal invariance, we have no basis for extrapolating from the known to the unknown and, therefore, no way of reaching general conclusions from a finite number of observations. (Since the assumption is itself vindicated by induction, it can in no way “prove” the validity of induction - an endeavor virtually abandoned after Hume demonstrated its futility two centuries ago)."[51]
Empirism holds that the landmark of scientific theories is their verifiability by induction from evidence.
Emprism has stood in contrast to rationalism, the opposing position which holds that knowledge is created by the human intellect, not by observation. The most recent and most sophisticated version of rationalism is critical rationalism, which attempts to acknowledge the fact that a connection exists between observation and theories, but rejects the way that empirism claims the nature of this connection to be. More specifically, critical rationalism claims that theories are not generated by observation, but the other way around, observation is made in the light of theories—it is "theory-laden" and never neutral—and that the only way a theory can be affected by observation is when comes in conflict with observation. In this view, there is no induction, only deduction with the key being the modus tollens. Critical rationalism acordingly proposes falsifiability as the landmark of empirical theories and falsification as the empirical method. It argues for the ability of science to increase the scope of testable knowledge, but at the same time against its authority, by emphasizing its inherent fallibility. It proposes that science should be content with the rational elimination of errors in its theories, not in seeking for their verification (such as claiming certain or probable proof or disproof; both the proposal and falsification of a theory are only of methodological, conjectural, and tentative character in critical rationalism).[52] This position, first brought forward by austrian-british philosopher Karl Popper, stands in sharp opposition to the prevalent popular as well as academic views on epistemology and the philosophy of science. It controversially implies that evidence[53] and scientific method do not actually exist.[54] Popper held that there is only one method, and that this method is universal, not in any way specific to science: The negative method of trial and error. It covers not only all products of the human mind, including science, mathematics, philosophy, art and so on, but also the evolution of life.[55] Popper especially questioned those positions that make a difference between natural and social sciences and criticized the prevalent philosophy of the social sciences as scientistic, as a mere imitation of the actual practice in the natural sciences. In this context, he contributed to the Positivism dispute, a philosophical dispute between Critical rationalism (Popper, Albert) and the Frankfurt School (Adorno, Habermas) about the methodology of the social sciences.[56] In contrast to positivism, which argues that science makes predictions that are guaranteed by evidence or at least made highly probable, or made more probable than can be achieved by other methods, Popper held the exact opposite to be true: Scientific theories are good because they are almost certainly false, which is the same as saying very improbable or easily falsifiable – yet cannot be successfully falsified (which, according to Popper, is emphatically not saying that they are in any way likely not to be falsified in the next instant, any time in the future, or over the long run). Popper, together with students William W. Bartley and David Miller, also questioned the classical theory of rationality for which rational knowledge in general, and scientific knowledge in particular stands out as knowledge that can be justified in a way that other claims cannot be justified (justified by evidence, by verification, by high probability). Popper criticized the very concept of justification (see justificationism) and argued that the only purpose of rationality is to eliminate false ideas by criticism (for non-empirical claims) and falsification (for empirical claims). He held that rationality has no way of justifying or sanctioning ideas. Popper, Bartley and Miller also argued against limits of rationality, especially against seeing falsifiability as a limit of rationality rather than merlely a limit of observability.
Another position, Instrumentalism, colloquially termed "shut up and calculate", rejects the concept of truth and emphasizes merely the utility of theories as instruments for explaining and predicting phenomena.[57] It essentially claims that scientific theories are black boxes with only their input (initial conditions) and output (predictions) being relevant. Consequences, notions and logical structure of the theories are claimed to be something that should simply be ignored and that scientists shouldn't make a fuss about (see interpretations of quantum mechanics).
A position often cited in political debates to conquer controverial views like creationism that purport to be scientific is methodological naturalism. It maintains that scientific investigation must adhere to empirical study and independent verification as a process for properly developing and evaluating natural explanations for observable phenomena.[58] Methodological naturalism, therefore, rejects supernatural explanations, arguments from authority and biased observational studies.
origin of science
This article is about the general term "Science", particularly as it refers to experimental sciences. For the specific topics of study by scientists, see natural science.
For other uses, see Science (disambiguation).
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v · d · e
Science (from the Latin scientia, meaning "knowledge") is an enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the world.[1][2][3][4] An older meaning still in use today is that of Aristotle, for whom scientific knowledge was a body of reliable knowledge that can be logically and rationally explained (see "History and etymology" section below).[5]
Since classical antiquity science as a type of knowledge was closely linked to philosophy, the way of life dedicated to discovering such knowledge. And into early modern times the two words, "science" and "philosophy", were sometimes used interchangeably in the English language. By the 17th century, "natural philosophy" (which is today called "natural science") could be considered separately from "philosophy" in general.[6] But "science" continued to also be used in a broad sense denoting reliable knowledge about a topic, in the same way it is still used in modern terms such as library science or political science.
The narrower sense of "science" that is common today developed as a part of science became a distinct enterprise of defining "laws of nature", based on early examples such as Kepler's laws, Galileo's laws, and Newton's laws of motion. In this period it became more common to refer to natural philosophy as "natural science". Over the course of the 19th century, the word "science" became increasingly associated with the disciplined study of the natural world including physics, chemistry, geology and biology. This sometimes left the study of human thought and society in a linguistic limbo, which was resolved by classifying these areas of academic study as social science. Similarly, several other major areas of disciplined study and knowledge exist today under the general rubric of "science", such as formal science and applied science.
For other uses, see Science (disambiguation).
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Theoretical biology · Toxicology · Zoology
Chemistry
Acid-base reaction theories · Alchemy
Analytical chemistry · Astrochemistry
Biochemistry · Crystallography
Environmental chemistry · Food science
Geochemistry · Green chemistry
Inorganic chemistry · Materials science
Molecular physics · Nuclear chemistry
Organic chemistry · Photochemistry
Physical chemistry · Radiochemistry
Solid-state chemistry · Stereochemistry
Supramolecular chemistry
Surface science · Theoretical chemistry
Earth sciences
Atmospheric sciences · Ecology
Environmental science · Geodesy
Geology · Geomorphology
Geophysics · Glaciology · Hydrology
Limnology · Mineralogy · Oceanography
Paleoclimatology · Palynology
Physical geography · Soil science
Space science
Physics
Applied physics · Atomic physics
Computational physics
Condensed matter physics
Experimental physics · Mechanics
Particle physics · Plasma physics
Quantum mechanics (introduction)
Solid mechanics · Theoretical physics
Thermodynamics · Entropy
General relativity · M-theory
Special relativity
Social and
behavioral sciences
Anthropology · Archaeology
Criminology · Demography
Economics · Geography
History · Linguistics
Political science · Psychology
Sociology
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Agricultural · Aerospace · Biomedical · Chemical · Civil
Computer · Electrical · Fire protection
Genetic · Industrial · Mechanical · Military
Mining · Nuclear · Security Science · Software
Health sciences
Biological engineering · Dentistry
Epidemiology · Health care · Medicine
Nursing · Pharmacy · Social work
Veterinary medicine
Formal sciences
Computer science
Logic
Mathematics
Statistics
Related topics
Interdisciplinarity
Applied physics · Artificial intelligence
Bioethics · Bioinformatics · Biogeography
Biomedical engineering · Biostatistics
Cognitive science · Computational linguistics
Cultural studies · Cybernetics
Environmental studies · Ethnic studies
Evolutionary psychology · Forestry
Health · Library science · Logic
Mathematical biology · Mathematical physics
Scientific modelling · Neural engineering
Neuroscience · Political economy
Science and technology studies
Science studies · Semiotics · Sociobiology
Systems theory · Transdisciplinarity
Urban planning
Scientific method
History of science
Philosophy of science
Science policy
Humanities
Fringe science
Pseudoscience
v · d · e
Science (from the Latin scientia, meaning "knowledge") is an enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the world.[1][2][3][4] An older meaning still in use today is that of Aristotle, for whom scientific knowledge was a body of reliable knowledge that can be logically and rationally explained (see "History and etymology" section below).[5]
Since classical antiquity science as a type of knowledge was closely linked to philosophy, the way of life dedicated to discovering such knowledge. And into early modern times the two words, "science" and "philosophy", were sometimes used interchangeably in the English language. By the 17th century, "natural philosophy" (which is today called "natural science") could be considered separately from "philosophy" in general.[6] But "science" continued to also be used in a broad sense denoting reliable knowledge about a topic, in the same way it is still used in modern terms such as library science or political science.
The narrower sense of "science" that is common today developed as a part of science became a distinct enterprise of defining "laws of nature", based on early examples such as Kepler's laws, Galileo's laws, and Newton's laws of motion. In this period it became more common to refer to natural philosophy as "natural science". Over the course of the 19th century, the word "science" became increasingly associated with the disciplined study of the natural world including physics, chemistry, geology and biology. This sometimes left the study of human thought and society in a linguistic limbo, which was resolved by classifying these areas of academic study as social science. Similarly, several other major areas of disciplined study and knowledge exist today under the general rubric of "science", such as formal science and applied science.
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