Junior Langi and History of physics: Difference between pages

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{{histOfScience}}
{{Infobox rugby league biography
The modern discipline of '''[[physics]]''' emerged in the 17th century following in traditions of inquiry established by [[Galileo Galilei]], [[René Descartes]], [[Isaac Newton]], and other [[natural philosophy|natural philosophers]].{{Fact|date=September 2008}} Prior to this time, a unified field of “physics” did not exist in the way that the term is currently understood.<ref>{{Harvtxt|Dear|1995}}</ref>{{Fact|date=September 2008}}
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Elements of what became physics were drawn primarily from the fields of [[astronomy]], [[optics]], and [[mechanics]], which were methodologically united through the study of [[geometry]]. These disciplines began in [[Ancient history|Antiquity]] with the [[Babylonian astronomy|Babylonians]] and with [[Hellenistic civilization|Hellenistic]] writers such as [[Archimedes]] and [[Ptolemy]], then passed on to the [[Physics in medieval Islam|Arabic-speaking world]] where they were critiqued and developed into a more physical and [[experiment]]al tradition by scientists such as [[Ibn al-Haytham]] and [[Abū Rayhān Bīrūnī]],<ref>{{Harvtxt|Glick|Livesey|Wallis|2005|p=89-90}}</ref><ref name=Rozhanskaya-642>Mariam Rozhanskaya and I. S. Levinova (1996), "Statics", p. 642, in {{Harvtxt|Rashed|Morelon|1996|pp=614-642}}:
'''Junior Langi''' (born [[August 2]], [[1981]]) is a former centre for the [[Salford City Reds]] [[rugby league]] team.
{{quote|"Using a whole body of mathematical methods (not only those inherited from the antique theory of ratios and infinitesimal techniques, but also the methods of the contemporary algebra and fine calculation techniques), Arabic scientists raised statics to a new, higher level. The classical results of Archimedes in the theory of the centre of gravity were generalized and applied to three-dimensional bodies, the theory of ponderable lever was founded and the 'science of gravity' was created and later further developed in medieval Europe. The phenomena of statics were studied by using the dynamic approach so that two trends - statics and dynamics - turned out to be inter-related within a single science, mechanics."}}
{{quote|"The combination of the dynamic approach with Archimedean hydrostatics gave birth to a direction in science which may be called medieval hydrodynamics."}}
{{quote|"Archimedean statics formed the basis for creating the fundamentals of the science on specific weight. Numerous fine experimental methods were developed for determining the specific weight, which were based, in particular, on the theory of balances and weighing. The classical works of al-Biruni and al-Khazini can by right be considered as the beginning of the application of experimental methods in medieval science."}}
{{quote|"Arabic statics was an essential link in the progress of world science. It played an important part in the prehistory of classical mechanics in medieval Europe. Without it classical mechanics proper could probably not have been created."}}</ref> before eventually passing on to [[Western Europe]] where they were studied by scholars such as [[Roger Bacon]] and [[Witelo]]. They were thought of as technical in character and many philosophers generally did not perceive their descriptive content as representing a philosophically significant knowledge of the natural world. Similar mathematical traditions also existed in ancient [[History of science and technology in China|Chinese]] and [[History of Indian science and technology|Indian sciences]].


Meanwhile, [[philosophy]], including what was called [[Aristotelian physics|“physics”]], focused on explanatory (rather than descriptive) schemes developed around the [[Aristotle|Aristotelian]] idea of the four types of [[causation|“causes”]]. According to [[Aristotelianism|Aristotelian]] and, later, [[Scholasticism|Scholastic]] physics, things moved in the way that they did because it was part of their essential nature to do so. Celestial objects were thought to move in circles, because perfect circular motion was considered an innate property of objects that existed in the uncorrupted realm of the [[celestial spheres]]. The [[theory of impetus]], the ancestor to the concepts of [[inertia]] and [[momentum]], also belonged to this philosophical tradition, and was developed by [[Medieval philosophy|medieval philosophers]] such as [[John Philoponus]], [[Avicenna]] and [[Jean Buridan]]. The physical traditions in ancient [[Chinese philosophy|China]] and [[Indian philosophy|India]] were also largely philosophical.
While attending Auburn Trinity College, Langi played for the [[Australia national schoolboys rugby league team|Australian Schoolboys team]] in 1999.<ref>{{cite web |title=SportingPulse Homepage for Australian Secondary Schools Rugby League |url=http://www.sportingpulse.com/assoc_page.cgi?c=7-2130-0-0-0&sID=26424 |accessdate=2008-10-10 | publisher=''SportingPulse''}}</ref>
In the philosophical tradition of "physics", motions below the lunar sphere were seen as imperfect, and thus could not be expected to exhibit consistent motion. More idealized motion in the “sublunary” realm could only be achieved through artifice, and prior to the 17th century, many philosophers did not view artificial experiments as a valid means of learning about the natural world. Instead, physical explanations in the sublunary realm revolved around tendencies. Stones contained the element earth, and earthy objects tended to move in a straight line toward the center of the universe (which the earth was supposed to be situated around) unless otherwise prevented from doing so. Other physical explanations, which would not later be considered within the bounds of physics, followed similar reasoning. For instance, people tended to think, because people were, by their essential nature, thinking animals.


{{see|History of astronomy|Aristotelian physics}}
Junior was born in New Zealand with Niueian and Tongan heritage. Previously, Junior played for the [[St. George Illawarra Dragons]], [[Melbourne Storm]] and [[Parramatta Eels]].


==Emergence of experimental method and physical optics==
Langi signed for Salford in 2005. He retired from the sport in December 2006 due to an eye condition and returned home. Without the operation he retuned home for Junior could have lost his sight completely. He retired at the young age of only 25
{{see|History of scientific method|History of optics|Science in the Middle Ages}}


The use of experiments in the sense of [[empirical]] procedures<ref>{{Harvtxt|Smith|1996|p=x}}</ref> in [[geometrical optics]] dates back to second century [[History of Roman Egypt|Roman Egypt]], where [[Ptolemy]] carried out several early such experiments on [[Reflection (mathematics)|reflection]], [[refraction]] and [[binocular vision]].<ref>{{Harvtxt|Smith|1996|p=18}}</ref> Due to his [[Platonism|Platonic]] methodological paradigm of "saving the appearances", however, he discarded or [[Rationalization (psychology)|rationalized]] any empirical data that did not support his theories,<ref>{{Harvtxt|Smith|1996|p=19}}</ref> as the idea of experiment did not hold any importance in Antiquity.<ref>{{Harvtxt|Tybjerg|2002|p=350}}</ref> The incorrect [[Emission theory (vision)|emission theory of vision]] thus continued to dominate optics through to the 10th century.
Junior is married to Kelela Misionare and has a daughter named Roslyn Taoto Langi.
Son of Tausinga and Taoto Langi, sibilings Joseph Langi , Ana Langi and FisiLau Langi


[[Image:Ibn al-Haytham.png|thumb|150px|right|[[Ibn al-Haytham]] (965-1039)]]
==External links==
*[http://www.salfordadvertiser.co.uk/sport/salfordreds/news/s/221/221186_fade_to_gray.html]


The turn of the [[2nd millennium|second millennium]] saw the emergence of [[experimental physics]] with the development of an [[scientific method|experimental method]] emphasizing the role of [[experiment]]ation as a form of proof in scientific inquiry, and the development of [[physical optics]] where the mathematical discipline of geometrical optics was successfully unified with the philosophical field of physics. The [[Physics in medieval Islam|Iraqi physicist]], [[Ibn al-Haytham]] (Alhazen), is considered a central figure in this shift in physics from a philosophical activity to an experimental and mathematical one, and the shift in optics from a mathematical discipline to a physical and experimental one.<ref name=Thiele/><ref name=Thiele-2005b/><ref name=Toomer>{{Harvtxt|Toomer|1964}}</ref><ref name=Sabra/><ref>{{Harvtxt|Rashed|Armstrong|1994|pp=345-6}}</ref><ref name=Smith>{{Harvtxt|Smith|1996|p=57}}</ref> Due to his [[Positivism|positivist]] approach,<ref name=Rashed>{{Harvtxt|Rashed|2007|p=19}}: {{quote|"In reforming optics he as it were adopted ‘‘positivism’’ (before the term was invented): we do not go beyond experience, and we cannot be content to use pure concepts in investigating natural phenomena. Understanding of these cannot be acquired without mathematics. Thus, once he has assumed light is a material substance, Ibn al-Haytham does not discuss its nature further, but confines himself to considering its propagation and diffusion. In his optics ‘‘the smallest parts of light’’, as he calls them, retain only properties that can be treated by geometry and verified by experiment; they lack all sensible qualities except energy."}}</ref> his ''Doubts Concerning Ptolemy'' insisted on [[scientific demonstration]] and criticized Ptolemy's [[confirmation bias]] and [[Conjecture|conjectural]] undemonstrated theories.<ref>{{Harvtxt|Sabra|1998|p=300}}</ref> His ''[[Book of Optics]]'' (1021) was the earliest successful attempt at unifying a mathematical discipline (geometrical optics) with the philosophical field of physics, to create the modern science of physical optics. An important part of this was the intromission theory of [[visual perception|vision]], which in order to prove, he developed an experimental method to [[Hypothesis testing|test his hypothesis]].<ref name=Thiele>{{Harvtxt|Thiele|2005a}}: {{quote|“Through a closer examination of Ibn al-Haytham's conceptions of [[mathematical model]]s and of the role they play in his theory of [[sense]] [[perception]], it becomes evident that he was the true founder of physics in the modern sense of the word; in fact he anticipated by six centuries the fertile ideas that were to mark the beginning of this new branch of science.”}}</ref><ref name=Thiele-2005b>{{Harvtxt|Thiele|2005b}}: {{quote|"Schramm showed that already some centuries before Galileo, experimental physics had its roots in Ibn al-Haytham."}}</ref><ref name=Toomer/><ref name=Sabra>{{Harvtxt|Sabra|2003|pp=91-2}}</ref><ref name=Smith/><ref name=Gorini>{{Harvtxt|Gorini|2003}}: {{quote|"According to the majority of the historians al-Haytham was the pioneer of the modern scientific method. With his book he changed the meaning of the term optics and established experiments as the norm of proof in the field. His investigations are based not on abstract theories, but on experimental evidences and his experiments were systematic and repeatable."}}</ref> He conducted various experiments to prove his intromission theory<ref>G. A. Russell, "Emergence of Physiological Optics", pp. 686-7, in {{Harvtxt|Rashed|Morelon|1996}}</ref> and other hypotheses on light and vision.<ref>{{Harvtxt|Sabra|1989}}</ref> The ''Book of Optics'' established experimentation as the norm of proof in optics,<ref name=Gorini/> and gave optics a physico-mathematical conception at a much earlier date than the other mathematical disciplines.<ref>{{Harv|Dijksterhuis|2004|pp=113-5}}: {{quote|"Through the influential work of Alhacen the onset of a physico-mathematical conception of optics was established at a much earlier time than would be the case in the other mathematical sciences."}}</ref> His ''On the Light of the Moon'' also attempted to combine mathematical astronomy with physics, a field now known as [[astrophysics]], to formulate several astronomical hypotheses which he proved through experimentation.<ref name=Toomer/>
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[[Category:Australian Schoolboy players]]


==Galileo Galilei and the rise of physico-mathematics==
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{{main|Galileo Galilei}}
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[[Image:Galileo.arp.300pix.jpg|thumb|150px|left|[[Galileo Galilei]] (1564-1642)]]

In the 17th century, [[Natural philosophy|natural philosophers]] began to mount a sustained attack on the [[Scholasticism|Scholastic]] philosophical program, and supposed that mathematical descriptive schemes adopted from such fields as mechanics and astronomy could actually yield universally valid characterizations of motion. The [[Grand Duchy of Tuscany|Tuscan]] mathematician [[Galileo Galilei]] was the central figure in the shift to this perspective. As a mathematician, Galileo’s role in the [[History of European research universities|university]] culture of his era was subordinated to the three major topics of study: [[law]], [[medicine]], and [[theology]] (which was closely allied to philosophy). Galileo, however, felt that the descriptive content of the technical disciplines warranted philosophical interest, particularly because mathematical analysis of astronomical observations—notably the radical analysis offered by astronomer [[Nicolaus Copernicus]] concerning the relative motions of the sun, earth, moon, and planets—indicated that philosophers’ statements about the nature of the universe could be shown to be in error. Galileo also performed mechanical experiments, and insisted that motion itself—regardless of whether that motion was natural or artificial—had universally consistent characteristics that could be described mathematically.

Galileo used his 1609 telescopic discovery of the [[Galilean moons|moons of Jupiter]], as published in his ''[[Sidereus Nuncius]]'' in 1610, to procure a position in the [[Medici]] court with the dual title of mathematician and philosopher. As a court philosopher, he was expected to engage in debates with philosophers in the Aristotelian tradition, and received a large audience for his own publications, such as ''[[The Assayer]]'' and ''[[Two New Sciences|Discourses and Mathematical Demonstrations Concerning Two New Sciences]]'', which was published abroad after he was placed under house arrest for his publication of ''[[Dialogue Concerning the Two Chief World Systems]]'' in 1632.<ref>{{Harvtxt|Drake|1978}}</ref><ref>{{Harvtxt|Biagioli|1993}}</ref>

Galileo’s interest in the mechanical experimentation and mathematical description in motion established a new natural philosophical tradition focused on experimentation. This tradition, combining with the non-mathematical emphasis on the collection of "experimental histories" by philosophical reformists such as [[William Gilbert]] and [[Francis Bacon]], drew a significant following in the years leading up to and following Galileo’s death, including [[Evangelista Torricelli]] and the participants in the [[Accademia del Cimento]] in Italy; [[Marin Mersenne]] and [[Blaise Pascal]] in France; [[Christiaan Huygens]] in the Netherlands; and [[Robert Hooke]] and [[Robert Boyle]] in England.

==The Cartesian philosophy of motion==
{{main| René Descartes}}
[[Image:Frans Hals - Portret van René Descartes.jpg|thumb|150px|right|[[René Descartes]] (1596-1650)]]
The French philosopher [[René Descartes]] was well-connected to, and influential within, the experimental philosophy networks. Descartes had a more ambitious agenda, however, which was geared toward replacing the Scholastic philosophical tradition altogether. Questioning the reality interpreted through the senses, Descartes sought to reestablish philosophical explanatory schemes by reducing all perceived phenomena to being attributable to the motion of an invisible sea of “corpuscles”. (Notably, he reserved human thought and [[God]] from his scheme, holding these to be separate from the physical universe). In proposing this philosophical framework, Descartes supposed that different kinds of motion, such as that of planets versus that of terrestrial objects, were not fundamentally different, but were merely different manifestations of an endless chain of corpuscular motions obeying universal principles. Particularly influential were his explanation for circular astronomical motions in terms of the vortex motion of corpuscles in space (Descartes argued, in accord with the beliefs, if not the methods, of the Scholastics, that a [[vacuum]] could not exist), and his explanation of [[gravity]] in terms of corpuscles pushing objects downward.<ref>{{Harvtxt|Shea|1991}}</ref><ref>{{Harvtxt|Garber|1992}}</ref><ref>{{Harvtxt|Gaukroger|2002}}</ref>

{{see|Mechanical explanations of gravitation}}

Descartes, like Galileo, was convinced of the importance of mathematical explanation, and he and his followers were key figures in the development of mathematics and geometry in the 17th century. Cartesian mathematical descriptions of motion held that all mathematical formulations had to be justifiable in terms of direct physical action, a position held by [[Christiaan Huygens|Huygens]] and the German philosopher [[Gottfried Leibniz]], who, while following in the Cartesian tradition, developed his own philosophical alternative to Scholasticism, which he outlined in his 1714 work, ''[[The Monadology]]''.

==Newtonian motion versus Cartesian motion==

[[Image:GodfreyKneller-IsaacNewton-1689.jpg|thumb|150px|left|Sir [[Isaac Newton]], (1643-1727)]]
In the late 17th and early 18th centuries, the Cartesian mechanical tradition was challenged by another philosophical tradition established by the [[Cambridge University]] mathematician [[Isaac Newton]]. Where [[René Descartes|Descartes]] held that all motions should be explained with respect to the immediate force exerted by corpuscles, Newton chose to describe universal motion with reference to a set of fundamental mathematical principles: his [[Newton's laws of motion|three laws of motion]] and the [[Newton's law of universal gravitation|law of gravitation]], which he introduced in his 1687 work ''[[Philosophiæ Naturalis Principia Mathematica|Mathematical Principles of Natural Philosophy]]''. Using these principles, Newton removed the idea that objects followed paths determined by natural shapes (such as [[Johannes Kepler|Kepler’s]] idea that planets moved naturally in [[ellipse]]s), and instead demonstrated that not only regularly observed paths, but all the future motions of any body could be deduced mathematically based on knowledge of their existing motion, their [[mass]], and the [[force]]s acting upon them. However, observed celestial motions did not precisely conform to a Newtonian treatment, and Newton, who was also deeply interested in [[theology]], imagined that God intervened to ensure the continued stability of the solar system.

[[Image:Gottfried Wilhelm von Leibniz.jpg|thumb|150px|right| [[Gottfried Leibniz]], (1646-1716)]]

Newton’s principles (but not his mathematical treatments) proved controversial with Continental philosophers, who found his lack of [[metaphysics|metaphysical]] explanation for movement and gravitation philosophically unacceptable. Beginning around 1700, a bitter rift opened between the Continental and British philosophical traditions, which were stoked by heated, ongoing, and viciously personal disputes between the followers of Newton and [[Gottfried Leibniz|Leibniz]] concerning priority over the analytical techniques of [[calculus]], which each had developed independently. Initially, the Cartesian and Leibnizian traditions prevailed on the Continent (leading to the dominance of the Leibnizian calculus notation everywhere except Britain). Newton himself remained privately disturbed at the lack of a philosophical understanding of gravitation, while insisting in his writings that none was necessary to infer its reality. As the 18th century progressed, Continental natural philosophers increasingly accepted the Newtonians’ willingness to forgo [[ontology|ontological]] metaphysical explanations for mathematically described motions.<ref>{{Harvtxt|Hall|1980}}</ref><ref>{{Harvtxt|Bertolini Meli|1993}}</ref><ref>{{Harvtxt|Guicciardini|1999}}</ref>

==Rational mechanics in the 18th century==
[[Image:Leonhard Euler 2.jpg|thumb|150px|left|[[Leonhard Euler]], (1707-1783)]]

The mathematical analytical traditions established by Newton and Leibniz flourished during the 18th century as more mathematicians learned calculus and elaborated upon its initial formulation. The application of mathematical analysis to problems of motion was known as rational mechanics, or mixed mathematics (and was later termed [[classical mechanics]]). This work primarily revolved around [[celestial mechanics]], although other applications were also developed, such as the Swiss mathematician [[Daniel Bernoulli|Daniel Bernoulli’s]] treatment of [[fluid dynamics]], which he introduced in his 1738 work ''Hydrodynamica''.<ref>{{Harvtxt|Darrigol|2005}}</ref>

Rational mechanics dealt primarily with the development of elaborate mathematical treatments of observed motions, using Newtonian principles as a basis, and emphasized improving the tractability of complex calculations and developing of legitimate means of analytical approximation. By the end of the century analytical treatments were rigorous enough to verify the stability of the [[solar system]] solely on the basis of Newton’s laws without reference to divine intervention—even as deterministic treatments of systems as simple as the [[n-body problem|three body problem]] in gravitation remained intractable.<ref>{{Harvtxt|Bos|1980}}</ref>
British work, carried on by mathematicians such as [[Brook Taylor]] and [[Colin Maclaurin]], fell behind Continental developments as the century progressed. Meanwhile, work flourished at scientific academies on the Continent, led by such mathematicians as [[Daniel Bernoulli]], [[Leonhard Euler]], [[Joseph-Louis Lagrange]], [[Pierre-Simon Laplace]], and [[Adrien-Marie Legendre]]. At the end of the century, the members of the [[French Academy of Sciences]] had attained clear dominance in the field.<ref>{{Harvtxt|Greenberg|1986}}</ref><ref>{{Harvtxt|Guicciardini|1989}}</ref><ref>{{Harvtxt| Guicciardini|1999}}</ref><ref>{{Harvtxt|Garber|1999}}</ref>

==Physical experimentation in the 18th and early 19th centuries==

At the same time, the experimental tradition established by [[Galileo Galilei|Galileo]] and his followers persisted. The [[Royal Society]] and the [[French Academy of Sciences]] were major centers for the performance and reporting of experimental work, and [[Isaac Newton|Newton]] was himself an influential experimenter, particularly in the field of [[optics]], where he was recognized for his [[prism (optics)|prism]] experiments dividing white light into its constituent spectrum of colors, as published in his 1704 book ''[[Opticks]]'' (which also advocated a particulate interpretation of light). Experiments in mechanics, optics, [[magnetism]], [[static electricity]], [[history of chemistry|chemistry]], and [[physiology]] were not clearly distinguished from each other during the 18th century, but significant differences in explanatory schemes and, thus, experiment design were emerging. Chemical experimenters, for instance, defied attempts to enforce a scheme of abstract Newtonian forces onto chemical affiliations, and instead focused on the isolation and classification of chemical substances and reactions.<ref>{{Harvtxt|Ben-Chaim|2004}}</ref>

Nevertheless, the separate fields remained tied together, most clearly through the theories of weightless [[imponderable fluid|“imponderable fluids"]], such as heat (“[[caloric theory|caloric]]”), [[history of electricity|electricity]], and [[phlogiston theory|phlogiston]] (which was rapidly overthrown as a concept following [[Antoine-Laurent Lavoisier|Lavoisier’s]] identification of [[oxygen]] gas late in the century). Assuming that these concepts were real fluids, their flow could be traced through a mechanical apparatus or chemical reactions. This tradition of experimentation led to the development of new kinds of experimental apparatus, such as the [[Leyden Jar]] and the [[Voltaic Pile]]; and new kinds of measuring instruments, such as the [[calorimeter]], and improved versions of old ones, such as the [[thermometer]]. Experiments also produced new concepts, such as the [[University of Glasgow]] experimenter [[Joseph Black|Joseph Black’s]] notion of [[latent heat]] and Philadelphia intellectual [[Benjamin Franklin|Benjamin Franklin’s]] characterization of electrical fluid as flowing between places of excess and deficit (a concept later reinterpreted in terms of positive and negative [[electric charge|charges]]).

[[Image:Faraday Michael Christmas lecture detail.jpg|thumb|200px|right|[[Michael Faraday]] (1791-1867) delivering the 1856 Christmas Lecture at the Royal Institution.]]
While it was recognized early in the 18th century that finding absolute theories of electrostatic and magnetic force akin to Newton’s principles of motion would be an important achievement, none were forthcoming. This impossibility only slowly disappeared as experimental practice became more widespread and more refined in the early years of the 19th century in places such as the newly-established [[Royal Institution]] in London, where [[John Dalton]] argued for an atomistic interpretation of chemistry, [[Thomas Young]] argued for the interpretation of light as a wave, and [[Michael Faraday]] established the phenomenon of [[Faraday's law of induction|electromagnetic induction]]. Meanwhile, the analytical methods of rational mechanics began to be applied to experimental phenomena, most influentially with the French mathematician [[Joseph Fourier|Joseph Fourier’s]] analytical treatment of the flow of heat, as published in 1822.<ref>{{Harvtxt|Heilbron|1979}}</ref><ref>{{Harvtxt|Buchwald|1989}}</ref><ref>{{Harvtxt|Golinski|1999}}</ref>

==Thermodynamics, statistical mechanics, and electromagnetic theory==

[[Image:Lord Kelvin photograph.jpg|thumb|150px|left|[[William Thomson]] (1824-1907), later Lord Kelvin]]
The establishment of a mathematical physics of [[energy]] between the 1850s and the 1870s expanded substantially on the physics of prior eras and challenged traditional ideas about how the physical world worked. While [[Pierre-Simon Laplace|Pierre-Simon Laplace’s]] work on celestial mechanics solidified a deterministically mechanistic view of objects obeying fundamental and totally reversible laws, the study of energy and particularly the flow of heat, threw this view of the universe into question. Drawing upon the engineering theory of [[Lazare Carnot|Lazare]] and [[Nicolas Léonard Sadi Carnot|Sadi Carnot]], and [[Émile Clapeyron]]; the experimentation of [[James Prescott Joule]] on the interchangeability of mechanical, chemical, thermal, and electrical forms of work; and his own [[Cambridge mathematical tripos]] training in mathematical analysis; the Glasgow physicist [[William Thomson, 1st Baron Kelvin|William Thomson]] and his circle of associates established a new mathematical physics relating to the exchange of different forms of energy and energy’s overall conservation (what is still accepted as the “[[first law of thermodynamics]]”). Their work was soon allied with the theories of similar but less-known work by the German physician [[Julius Robert von Mayer]] and physicist and physiologist [[Hermann von Helmholtz]] on the conservation of forces.

[[Image:Boltzmann2.jpg|thumb|150px|right|[[Ludwig Boltzmann]] (1844-1906)]]
Taking his mathematical cues from the heat flow work of [[Joseph Fourier]] (and his own religious and [[history of geology|geological]] convictions), Thomson believed that the dissipation of energy with time (what is accepted as the “[[second law of thermodynamics]]”) represented a fundamental principle of physics, which was expounded in Thomson and [[Peter Guthrie Tait|Peter Guthrie Tait’s]] influential work ''Treatise on Natural Philosophy''. However, other interpretations of what Thomson called [[thermodynamics]] were established through the work of the German physicist [[Rudolf Clausius]]. His [[statistical mechanics]], which was elaborated upon by [[Ludwig Boltzmann]] and the British physicist [[James Clerk Maxwell]], held that energy (including heat) was a measure of the speed of particles. Interrelating the statistical likelihood of certain states of organization of these particles with the energy of those states, Clausius reinterpreted the dissipation of energy to be the statistical tendency of molecular configurations to pass toward increasingly likely, increasingly disorganized states (coining the term “[[entropy]]” to describe the disorganization of a state). The statistical versus absolute interpretations of the second law of thermodynamics set up a dispute that would last for several decades (producing arguments such as “[[Maxwell's demon]]”), and that would not be held to be definitively resolved until the behavior of atoms was firmly established in the early 20th century.<ref>{{Harvtxt|Smith|Wise|1989}}</ref><ref>{{Harvtxt|Smith|1998}}</ref>
{{see|history of thermodynamics}}

Meanwhile, the new physics of energy transformed the analysis of electromagnetic phenomena, particularly through the introduction of the concept of the [[field (physics)|field]] and the publication of Maxwell’s 1873 ''[[A Treatise on Electricity and Magnetism|Treatise on Electricity and Magnetism]]'', which also drew upon theoretical work by German theoreticians such as [[Carl Friedrich Gauss]] and [[Wilhelm Eduard Weber|Wilhelm Weber]]. The encapsulation of heat in particulate motion, and the addition of electromagnetic forces to Newtonian dynamics established an enormously robust theoretical underpinning to physical observations. The prediction that light represented a transmission of energy in wave form through a “[[Luminiferous aether|luminiferous ether]]”, and the seeming confirmation of that prediction with Helmholtz student [[Heinrich Hertz|Heinrich Hertz’s]] 1888 detection of [[electromagnetic radiation]], was a major triumph for physical theory and raised the possibility that even more fundamental theories based on the field could soon be developed.<ref>{{Harvtxt|Buchwald|1985}}</ref><ref>{{Harvtxt|Jungnickel and McCormmanch|1986}}</ref><ref>{{Harvtxt|Hunt|1991}}</ref><ref>{{Harvtxt|Buchwald|1994}}</ref> Research on the transmission of electromagnetic waves began soon after, with the experiments conducted by physicists such as [[Nikola Tesla]], [[Jagadish Chandra Bose]] and [[Guglielmo Marconi]] during the 1890s leading to the [[invention of radio]].

==The emergence of a new physics circa 1900==
[[Image:Marie Curie (Nobel-physics).png|thumb|150px|left|[[Marie Curie|Marie Skłodowska Curie]] (1867-1934)]]

The triumph of Maxwell’s theories was undermined by inadequacies that had already begun to appear. The [[Michelson-Morley experiment]] failed to detect a shift in the [[speed of light]], which would have been expected as the earth moved at different angles with respect to the ether. The possibility explored by [[Hendrik Lorentz]], that the ether could compress matter, thereby rendering it undetectable, presented problems of its own as a compressed [[electron]] (detected in 1897 by British experimentalist [[J. J. Thomson]]) would prove unstable. Meanwhile, other experimenters began to detect unexpected forms of radiation: [[Wilhelm Röntgen]] caused a sensation with his discovery of [[x-ray]]s in 1895; in 1896 [[Henri Becquerel]] discovered that certain kinds of matter emit radiation on their own accord. [[Marie Curie|Marie]] and [[Pierre Curie]] coined the term “[[radioactive decay|radioactivity]]” to describe this property of matter, and isolated the radioactive elements [[radium]] and [[polonium]]. [[Ernest Rutherford]] and [[Frederick Soddy]] identified two of Becquerel’s forms of radiation with electrons and the element [[helium]]. In 1911 Rutherford established that the bulk of mass in atoms are concentrated in positively-charged nuclei with orbiting electrons, which was a theoretically unstable configuration. Studies of radiation and radioactive decay continued to be a preeminent focus for physical and chemical research through the 1930s, when the discovery of [[nuclear fission]] opened the way to the practical exploitation of what came to be called [[Nuclear energy|“atomic” energy]].

[[Image:Einstein patentoffice.jpg|thumb|150px|right|[[Albert Einstein]] (1879-1955)]]
Radical new physical theories also began to emerge in this same period. In 1905 [[Albert Einstein]], then a Bern patent clerk, argued that the speed of light was a constant in all [[Inertial frame of reference|inertial reference frames]] and that electromagnetic laws should remain valid independent of reference frame—assertions which rendered the ether “superfluous” to physical theory, and that held that observations of time and length varied relative to how the observer was moving with respect to the object being measured (what came to be called the “[[special relativity|special theory of relativity]]”). It also followed that mass and energy were interchangeable quantities according to the equation [[Mass-energy equivalence|E=mc<sup>2</sup>]]. In another paper published the same year, Einstein asserted that electromagnetic radiation was transmitted in discrete quantities (“[[quantum|quanta]]”), according to a constant that the theoretical physicist [[Max Planck]] had posited in 1900 to arrive at an accurate theory for the distribution of [[blackbody radiation]]—an assumption that explained the strange properties of the [[photoelectric effect]]. The Danish physicist [[Niels Bohr]] used this same constant in 1913 to explain the stability of [[Rutherford model|Rutherford’s atom]] as well as the frequencies of light emitted by hydrogen gas.
{{see|History of special relativity }}

==The radical years: general relativity and quantum mechanics==
The gradual acceptance of Einstein’s theories of relativity and the quantized nature of light transmission, and of Niels Bohr’s model of the atom created as many problems as they solved, leading to a full-scale effort to reestablish physics on new fundamental principles. Expanding relativity to cases of accelerating reference frames (the “[[general relativity|general theory of relativity]]”) in the 1910s, Einstein posited an equivalence between the inertial force of acceleration and the force of gravity, leading to the conclusion that space is curved and finite in size, and the prediction of such phenomena as [[gravitational lens]]ing and the distortion of time in gravitational fields.

{{see|History of general relativity}}

[[Image:Niels Bohr.jpg|thumb|150px|right|[[Niels Bohr]] (1885-1962)]]

The quantized theory of the atom gave way to a full-scale [[history of quantum mechanics|quantum mechanics]] in the 1920s. The quantum theory (which previously relied in the “correspondence” at large scales between the quantized world of the atom and the continuities of the “[[Physics in the Classical Limit|classical]]” world) was accepted when the [[Compton Effect]] established that light carries momentum and can scatter off particles, and when [[Louis de Broglie]] asserted that matter can be seen as behaving as a wave in much the same way as electromagnetic waves behave like particles ([[wave-particle duality]]). New principles of a “quantum” rather than a “classical” mechanics, formulated in [[Matrix mechanics|matrix-form]] by [[Werner Heisenberg]], [[Max Born]], and [[Pascual Jordan]] in 1925, were based on the probabilistic relationship between discrete “states” and denied the possibility of [[causality]]. [[Erwin Schrödinger]] established an equivalent theory based on waves in 1926; but Heisenberg’s 1927 “[[uncertainty principle]]” (indicating the impossibility of precisely and simultaneously measuring position and [[momentum]]) and the “[[Copenhagen interpretation]]” of quantum mechanics (named after Bohr’s home city) continued to deny the possibility of fundamental causality, though opponents such as Einstein would assert that “God does not play dice with the universe”.<ref>{{Harvtxt|Kragh|1999}}</ref> Also in the 1920s, [[Satyendra Nath Bose]]'s work on [[photon]]s and quantum mechanics provided the foundation for [[Bose-Einstein statistics]], the theory of the [[Bose-Einstein condensate]], and the discovery of the [[boson]].

{{see|history of quantum mechanics}}

==Constructing a new fundamental physics==
[[Image:Renormalized-vertex.png|thumbnail|left|200px|A “[[Feynman diagram]]” of a [[renormalization|renormalized]] vertex in [[quantum electrodynamics]].]]

As the philosophically inclined continued to debate the fundamental nature of the universe, quantum theories continued to be produced, beginning with [[Paul Dirac|Paul Dirac’s]] formulation of a relativistic quantum theory in 1927. However, attempts to quantize electromagnetic theory entirely were stymied throughout the 1930s by theoretical formulations yielding infinite energies. This situation was not considered adequately resolved until after [[World War II]] ended, when [[Julian Schwinger]], [[Richard Feynman]], and [[Sin-Itiro Tomonaga]] independently posited the technique of “[[renormalization]]”, which allowed for an establishment of a robust [[quantum electrodynamics]] (Q.E.D.).<ref>{{Harvtxt|Schweber|1994}}</ref>

Meanwhile, new theories of [[Elementary particle|fundamental particles]] proliferated with the rise of the idea of the [[quantum field theory|quantization of fields]] through “[[Exchange interaction|exchange forces]]” regulated by an exchange of short-lived [[Virtual particle|“virtual” particles]], which were allowed to exist according to the laws governing the uncertainties inherent in the quantum world. Notably, [[Hideki Yukawa]] proposed that the positive charges of the [[Atomic nucleus|nucleus]] were kept together courtesy of a powerful but short-range force mediated by a particle intermediate in mass between the size of an [[electron]] and a [[proton]]. This particle, called the “[[pion]]”, was identified in 1947, but it was part of a slew of particle discoveries beginning with the [[neutron]], the “[[positron]]” (a positively-charged “[[antimatter]]” version of the electron), and the “[[muon]]” (a heavier relative to the electron) in the 1930s, and continuing after the war with a wide variety of other particles detected in various kinds of apparatus: [[cloud chamber]]s, [[nuclear emulsion]]s, [[bubble chamber]]s, and [[Coincidence circuit|coincidence counters]]. At first these particles were found primarily by the [[ionization|ionized]] trails left by [[cosmic ray]]s, but were increasingly produced in newer and more powerful [[particle accelerator]]s.<ref>{{Harvtxt|Galison|1997}}</ref>

[[Image:First Gold Beam-Beam Collision Events at RHIC at 100 100 GeV c per beam recorded by STAR.jpg|thumb|right|300px|Thousands of particles explode from the collision point of two relativistic (100 [[GeV]] per ion) [[gold]] ions in the [[STAR detector]] of the [[Relativistic Heavy Ion Collider]]; an experiment done in order to investigate the properties of a [[quark gluon plasma]] such as the one thought to exist in the ultrahot first few microseconds after the [[big bang]]]]

The interaction of these particles by “[[scattering]]” and “[[particle decay|decay]]” provided a key to new fundamental quantum theories. [[Murray Gell-Mann]] and [[Yuval Ne'eman]] brought some order to these new particles by classifying them according to certain qualities, beginning with what Gell-Mann referred to as the “[[Eightfold way (physics)|Eightfold Way]]”, but proceeding into several different “octets” and “decuplets” which could predict new particles, most famously the {{SubatomicParticle|link=yes|Omega-}}, which was detected at [[Brookhaven National Laboratory]] in 1964, and which gave rise to the “[[quark]]” model of [[hadron]] composition. While the [[quark model]] at first seemed inadequate to describe [[Strong interaction|strong nuclear forces]], allowing the temporary rise of competing theories such as the [[S-Matrix]], the establishment of [[quantum chromodynamics]] in the 1970s finalized a set of fundamental and exchange particles, which allowed for the establishment of a “[[Standard Model|standard model]]” based on the mathematics of [[Gauge theory|gauge invariance]], which successfully described all forces except for gravity, and which remains generally accepted within the domain to which it is designed to be applied.<ref>{{Harvtxt|Kragh|1999}}</ref>

The “standard model” groups the [[electroweak interaction]] theory and [[quantum chromodynamics]] into a structure denoted by the gauge group ''SU(3)&times;SU(2)&times;U(1)''. The formulation of the unification of the electromagnetic and [[weak interaction]]s in the standard model is due to [[Abdus Salam]], [[Steven Weinberg]] and, subsequently, [[Sheldon Glashow]]. After the discovery, made at [[CERN]], of the existence of [[Neutral current|neutral weak currents]],<ref>F. J. Hasert ''et al.'' ''Phys. Lett.'' '''46B''' 121 (1973).</ref><ref>F. J. Hasert ''et al.'' ''Phys. Lett.'' '''46B''' 138 (1973).</ref><ref>F. J. Hasert ''et al.'' ''Nucl. Phys.'' '''B73''' 1(1974).</ref><ref>{{cite web|url=http://cerncourier.com/cws/article/cern/29168|title=The discovery of the weak neutral currents|date=2004-10-04|publisher=CERN courier|accessdate=2008-05-08}}</ref> mediated by the [[W and Z bosons|{{SubatomicParticle|Z boson}} boson]] foreseen in the standard model, the physicists Salam, Glashow and Weinberg received the 1979 [[Nobel Prize in Physics]] for their electroweak theory.<ref>{{cite web|title=The Nobel Prize in Physics 1979|url=http://www.nobel.se/physics/laureates/1979|publisher=[[Nobel Foundation]]|accessdate=2008-09-10}}</ref>

While accelerators have confirmed most aspects of the standard model by detecting expected particle interactions at various collision energies, no theory reconciling the [[general relativity|general theory of relativity]] with the standard model has yet been found, although “[[string theory]]” has provided one promising avenue forward. Since the 1970s, fundamental particle physics has provided insights into early universe [[cosmology]], particularly the “[[big bang]]” theory proposed as a consequence of Einstein’s general theory. However, starting from the 1990s, astronomical observations have also provided new challenges, such as the need for new explanations of galactic stability (the problem of [[dark matter]]), and [[accelerating universe|accelerating expansion of the universe]] (the problem of [[dark energy]]).

==The physical sciences==

With increased accessibility to and elaboration upon advanced analytical techniques in the 19th century, physics was defined as much, if not more, by those techniques than by the search for universal principles of motion and energy, and the fundamental nature of [[matter]]. Fields such as [[acoustics]], [[geophysics]], [[astrophysics]], [[aerodynamics]], [[plasma (physics)|plasma physics]], [[cryogenics|low-temperature physics]], and [[solid-state physics]] joined [[optics]], [[fluid dynamics]], [[electromagnetism]], and [[mechanics]] as areas of physical research. In the 20th century, physics also became closely allied with such fields as [[electrical engineering|electrical]], [[aerospace engineering|aerospace]], and [[materials science|materials]] engineering, and physicists began to work in government and industrial laboratories as much as in academic settings. Following World War II, the population of physicists increased dramatically, and came to be centered on the United States, while, in more recent decades, physics has become a more international pursuit than at any time in its previous history.

==See also==
* [[Famous physicists]]
* [[Nobel Prize in physics]]

==Further reading==
{{Wikiversity|History of Physics}}
* [http://www.newtonproject.sussex.ac.uk/prism.php?id=90 “Selected Works about Isaac Newton and His Thought”] from [http://www.newtonproject.sussex.ac.uk/ ''The Newton Project''].
* {{Citation | last=Dear| first=Peter | author-link= | year=2001 | publication-date=2001 | title=Revolutionizing the Sciences: European Knowledge and Its Ambitions, 1500-1700 | edition= | place= | publication-place=Princeton | publisher=Princeton University Press | isbn=0691088594 | oclc=46622656 }}.
* {{Citation | last=Nye | first=Mary Jo | author-link= | year=1996 | publication-date=1996 | title=Before Big Science: The Pursuit of Modern Chemistry and Physics, 1800-1940 | edition= | place= | publication-place=New York | publisher=Twayne | isbn=080579512X | oclc=185866968 34878783 }}.
* {{Citation | last=Segrè | first=Emilio | author-link= | year=1984 | publication-date=1984 | title=From Falling Bodies to Radio Waves: Classical Physicists and Their Discoveries | edition= | place= | publication-place=New York | publisher=W. H. Freeman |isbn=0-7167-1482-5 | oclc=9943504}}.
* {{Citation | last=Segrè | first=Emilio | author-link= | year=1980 | publication-date=1980 | title=From X-Rays to Quarks: Modern Physicists and Their Discoveries | edition= | place= | publication-place=San Francisco | publisher=W. H. Freeman |isbn=0-7167-1147-8 | oclc=237246197 56100286 5946636}}.
*Nina Byers and Gary Williams, ed., [http://www.cambridge.org/us/catalogue/catalogue.asp?isbn=9780521821971 ''OUT OF THE SHADOWS:Contributions of 20th Century Women to Physics''] Cambridge University Press, 2006 ISBN 0-5218-2197-1

==Notes==
{{reflist|2}}

==References==
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* {{Citation | last=Garber | first=Daniel | author-link= | year=1992 | publication-date=1992 | title=Descartes’ Metaphysical Physics | edition= | place= | publication-place=Chicago | publisher=University of Chicago Press}}.
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* {{Citation | last=Gaukroger | first=Stephen | author-link= | year=2002 | publication-date=2002 | title=Descartes’ System of Natural Philosophy | edition= | place= | publication-place=New York | publisher=Cambridge University Press}}.
* {{Citation |last1=Glick |first1=Thomas F. |last2=Livesey |first2=Steven John |last3=Wallis |first3=Faith |year=2005 |title=Medieval Science, Technology, and Medicine: An Encyclopedia |publisher=[[Routledge]] |isbn=0415969301 |oclc=218847614 58829023 61228669 }}
* {{Citation | last=Greenberg | first=John | author-link= | year=1986 | publication-date=1986 | title=Mathematical Physics in Eighteenth-Century France | journal=Isis | volume=77 | pages=59–78 | doi=10.1086/354039}}.
* {{Citation | last=Golinski | first=Jan | author-link= | year=1999 | publication-date=1999 | title=Science as Public Culture: Chemistry and Enlightenment in Britain, 1760-1820 | edition= | place= | publication-place=New York | publisher=Cambridge University Press}}.
* {{Citation |last=Gorini |first=Rosanna |title=Al-Haytham the man of experience. First steps in the science of vision |journal=Journal of the International Society for the History of Islamic Medicine |volume=2 |issue=4 |pages=53–55 |date=October 2003 |url=http://www.ishim.net/ishimj/4/10.pdf |format=pdf |accessdate=2008-09-25}}.
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* {{Citation | last=Kragh | first=Helge | author-link= | year=1999 | publication-date=1999 | title=Quantum Generations: A History of Physics in the Twentieth Century | edition= | place= | publication-place=Princeton | publisher=Princeton University Press}}.
*{{Citation | last1=Rashed | first1=R. | last2=Armstrong | first2=Angela | year=1994 | title=The Development of Arabic Mathematics | publisher=[[Springer Science+Business Media|Springer]] | isbn=0792325656 | oclc=29181926}}.
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*{{Citation |last=Rashed |first=R. |year=2007 |title=The Celestial Kinematics of Ibn al-Haytham |journal=Arabic Sciences and Philosophy |volume=17 |pages=7–55 |publisher=[[Cambridge University Press]] |doi=10.1017/S0957423907000355}}.
* {{Citation |last=Sabra |first=A. I. |author-link=A. I. Sabra |year=1989 |title=Ibn al-Haytham, The Optics of Ibn al-Haytham |volume=I |pages=90–1 |publisher=The Warburg Institute |publication-place=London}}.
* {{Citation |last=Sabra |first=A. I. |author-link=A. I. Sabra |year=1998 |title=Configuring the Universe: Aporetic, Problem Solving, and Kinematic Modeling as Themes of Arabic Astronomy |journal=Perspectives on Science |volume=6 |issue=3 |pages=288–330}}.
* {{Citation |last1=Sabra |first1=A. I. |author1-link=A. I. Sabra |last2=Hogendijk |first2=J. P. |year=2003 |title=The Enterprise of Science in Islam: New Perspectives |pages=85–118 |publisher=[[MIT Press]] |isbn=0262194821 |oclc=237875424 50252039}}.
* {{Citation | last=Schweber | first=Silvan | author-link= | year=1994 | publication-date=1994 | title=QED and the Men Who Made It: Dyson, Feynman, Schwinger, and Tomonaga | edition= | place= | publication-place=Princeton | publisher=Princeton University Press}}.
* {{Citation | last=Shea | first=William| author-link= | year=1991 | publication-date=1991 | title=The Magic of Numbers and Motion: The Scientific Career of René Descartes | edition= | place= | publication-place=Canton, MA | publisher=Science History Publications}}.
*{{Citation |last=Smith |first=A. Mark |year=1996 |title=Ptolemy's Theory of Visual Perception: An English Translation of the Optics with Introduction and Commentary |publisher=Diane Publishing |isbn=0871698625 |oclc=185537531 34724889}}.
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{{portal|Physics}}

[[Category:History of physics| ]]
[[Category:Physics]]

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Revision as of 07:26, 12 October 2008

The modern discipline of physics emerged in the 17th century following in traditions of inquiry established by Galileo Galilei, René Descartes, Isaac Newton, and other natural philosophers.[citation needed] Prior to this time, a unified field of “physics” did not exist in the way that the term is currently understood.[1][citation needed]

Elements of what became physics were drawn primarily from the fields of astronomy, optics, and mechanics, which were methodologically united through the study of geometry. These disciplines began in Antiquity with the Babylonians and with Hellenistic writers such as Archimedes and Ptolemy, then passed on to the Arabic-speaking world where they were critiqued and developed into a more physical and experimental tradition by scientists such as Ibn al-Haytham and Abū Rayhān Bīrūnī,[2][3] before eventually passing on to Western Europe where they were studied by scholars such as Roger Bacon and Witelo. They were thought of as technical in character and many philosophers generally did not perceive their descriptive content as representing a philosophically significant knowledge of the natural world. Similar mathematical traditions also existed in ancient Chinese and Indian sciences.

Meanwhile, philosophy, including what was called “physics”, focused on explanatory (rather than descriptive) schemes developed around the Aristotelian idea of the four types of “causes”. According to Aristotelian and, later, Scholastic physics, things moved in the way that they did because it was part of their essential nature to do so. Celestial objects were thought to move in circles, because perfect circular motion was considered an innate property of objects that existed in the uncorrupted realm of the celestial spheres. The theory of impetus, the ancestor to the concepts of inertia and momentum, also belonged to this philosophical tradition, and was developed by medieval philosophers such as John Philoponus, Avicenna and Jean Buridan. The physical traditions in ancient China and India were also largely philosophical.

In the philosophical tradition of "physics", motions below the lunar sphere were seen as imperfect, and thus could not be expected to exhibit consistent motion. More idealized motion in the “sublunary” realm could only be achieved through artifice, and prior to the 17th century, many philosophers did not view artificial experiments as a valid means of learning about the natural world. Instead, physical explanations in the sublunary realm revolved around tendencies. Stones contained the element earth, and earthy objects tended to move in a straight line toward the center of the universe (which the earth was supposed to be situated around) unless otherwise prevented from doing so. Other physical explanations, which would not later be considered within the bounds of physics, followed similar reasoning. For instance, people tended to think, because people were, by their essential nature, thinking animals.

Emergence of experimental method and physical optics

The use of experiments in the sense of empirical procedures[4] in geometrical optics dates back to second century Roman Egypt, where Ptolemy carried out several early such experiments on reflection, refraction and binocular vision.[5] Due to his Platonic methodological paradigm of "saving the appearances", however, he discarded or rationalized any empirical data that did not support his theories,[6] as the idea of experiment did not hold any importance in Antiquity.[7] The incorrect emission theory of vision thus continued to dominate optics through to the 10th century.

Ibn al-Haytham (965-1039)

The turn of the second millennium saw the emergence of experimental physics with the development of an experimental method emphasizing the role of experimentation as a form of proof in scientific inquiry, and the development of physical optics where the mathematical discipline of geometrical optics was successfully unified with the philosophical field of physics. The Iraqi physicist, Ibn al-Haytham (Alhazen), is considered a central figure in this shift in physics from a philosophical activity to an experimental and mathematical one, and the shift in optics from a mathematical discipline to a physical and experimental one.[8][9][10][11][12][13] Due to his positivist approach,[14] his Doubts Concerning Ptolemy insisted on scientific demonstration and criticized Ptolemy's confirmation bias and conjectural undemonstrated theories.[15] His Book of Optics (1021) was the earliest successful attempt at unifying a mathematical discipline (geometrical optics) with the philosophical field of physics, to create the modern science of physical optics. An important part of this was the intromission theory of vision, which in order to prove, he developed an experimental method to test his hypothesis.[8][9][10][11][13][16] He conducted various experiments to prove his intromission theory[17] and other hypotheses on light and vision.[18] The Book of Optics established experimentation as the norm of proof in optics,[16] and gave optics a physico-mathematical conception at a much earlier date than the other mathematical disciplines.[19] His On the Light of the Moon also attempted to combine mathematical astronomy with physics, a field now known as astrophysics, to formulate several astronomical hypotheses which he proved through experimentation.[10]

Galileo Galilei and the rise of physico-mathematics

Galileo Galilei (1564-1642)

In the 17th century, natural philosophers began to mount a sustained attack on the Scholastic philosophical program, and supposed that mathematical descriptive schemes adopted from such fields as mechanics and astronomy could actually yield universally valid characterizations of motion. The Tuscan mathematician Galileo Galilei was the central figure in the shift to this perspective. As a mathematician, Galileo’s role in the university culture of his era was subordinated to the three major topics of study: law, medicine, and theology (which was closely allied to philosophy). Galileo, however, felt that the descriptive content of the technical disciplines warranted philosophical interest, particularly because mathematical analysis of astronomical observations—notably the radical analysis offered by astronomer Nicolaus Copernicus concerning the relative motions of the sun, earth, moon, and planets—indicated that philosophers’ statements about the nature of the universe could be shown to be in error. Galileo also performed mechanical experiments, and insisted that motion itself—regardless of whether that motion was natural or artificial—had universally consistent characteristics that could be described mathematically.

Galileo used his 1609 telescopic discovery of the moons of Jupiter, as published in his Sidereus Nuncius in 1610, to procure a position in the Medici court with the dual title of mathematician and philosopher. As a court philosopher, he was expected to engage in debates with philosophers in the Aristotelian tradition, and received a large audience for his own publications, such as The Assayer and Discourses and Mathematical Demonstrations Concerning Two New Sciences, which was published abroad after he was placed under house arrest for his publication of Dialogue Concerning the Two Chief World Systems in 1632.[20][21]

Galileo’s interest in the mechanical experimentation and mathematical description in motion established a new natural philosophical tradition focused on experimentation. This tradition, combining with the non-mathematical emphasis on the collection of "experimental histories" by philosophical reformists such as William Gilbert and Francis Bacon, drew a significant following in the years leading up to and following Galileo’s death, including Evangelista Torricelli and the participants in the Accademia del Cimento in Italy; Marin Mersenne and Blaise Pascal in France; Christiaan Huygens in the Netherlands; and Robert Hooke and Robert Boyle in England.

The Cartesian philosophy of motion

René Descartes (1596-1650)

The French philosopher René Descartes was well-connected to, and influential within, the experimental philosophy networks. Descartes had a more ambitious agenda, however, which was geared toward replacing the Scholastic philosophical tradition altogether. Questioning the reality interpreted through the senses, Descartes sought to reestablish philosophical explanatory schemes by reducing all perceived phenomena to being attributable to the motion of an invisible sea of “corpuscles”. (Notably, he reserved human thought and God from his scheme, holding these to be separate from the physical universe). In proposing this philosophical framework, Descartes supposed that different kinds of motion, such as that of planets versus that of terrestrial objects, were not fundamentally different, but were merely different manifestations of an endless chain of corpuscular motions obeying universal principles. Particularly influential were his explanation for circular astronomical motions in terms of the vortex motion of corpuscles in space (Descartes argued, in accord with the beliefs, if not the methods, of the Scholastics, that a vacuum could not exist), and his explanation of gravity in terms of corpuscles pushing objects downward.[22][23][24]

Descartes, like Galileo, was convinced of the importance of mathematical explanation, and he and his followers were key figures in the development of mathematics and geometry in the 17th century. Cartesian mathematical descriptions of motion held that all mathematical formulations had to be justifiable in terms of direct physical action, a position held by Huygens and the German philosopher Gottfried Leibniz, who, while following in the Cartesian tradition, developed his own philosophical alternative to Scholasticism, which he outlined in his 1714 work, The Monadology.

Newtonian motion versus Cartesian motion

Sir Isaac Newton, (1643-1727)

In the late 17th and early 18th centuries, the Cartesian mechanical tradition was challenged by another philosophical tradition established by the Cambridge University mathematician Isaac Newton. Where Descartes held that all motions should be explained with respect to the immediate force exerted by corpuscles, Newton chose to describe universal motion with reference to a set of fundamental mathematical principles: his three laws of motion and the law of gravitation, which he introduced in his 1687 work Mathematical Principles of Natural Philosophy. Using these principles, Newton removed the idea that objects followed paths determined by natural shapes (such as Kepler’s idea that planets moved naturally in ellipses), and instead demonstrated that not only regularly observed paths, but all the future motions of any body could be deduced mathematically based on knowledge of their existing motion, their mass, and the forces acting upon them. However, observed celestial motions did not precisely conform to a Newtonian treatment, and Newton, who was also deeply interested in theology, imagined that God intervened to ensure the continued stability of the solar system.

Gottfried Leibniz, (1646-1716)

Newton’s principles (but not his mathematical treatments) proved controversial with Continental philosophers, who found his lack of metaphysical explanation for movement and gravitation philosophically unacceptable. Beginning around 1700, a bitter rift opened between the Continental and British philosophical traditions, which were stoked by heated, ongoing, and viciously personal disputes between the followers of Newton and Leibniz concerning priority over the analytical techniques of calculus, which each had developed independently. Initially, the Cartesian and Leibnizian traditions prevailed on the Continent (leading to the dominance of the Leibnizian calculus notation everywhere except Britain). Newton himself remained privately disturbed at the lack of a philosophical understanding of gravitation, while insisting in his writings that none was necessary to infer its reality. As the 18th century progressed, Continental natural philosophers increasingly accepted the Newtonians’ willingness to forgo ontological metaphysical explanations for mathematically described motions.[25][26][27]

Rational mechanics in the 18th century

Leonhard Euler, (1707-1783)

The mathematical analytical traditions established by Newton and Leibniz flourished during the 18th century as more mathematicians learned calculus and elaborated upon its initial formulation. The application of mathematical analysis to problems of motion was known as rational mechanics, or mixed mathematics (and was later termed classical mechanics). This work primarily revolved around celestial mechanics, although other applications were also developed, such as the Swiss mathematician Daniel Bernoulli’s treatment of fluid dynamics, which he introduced in his 1738 work Hydrodynamica.[28]

Rational mechanics dealt primarily with the development of elaborate mathematical treatments of observed motions, using Newtonian principles as a basis, and emphasized improving the tractability of complex calculations and developing of legitimate means of analytical approximation. By the end of the century analytical treatments were rigorous enough to verify the stability of the solar system solely on the basis of Newton’s laws without reference to divine intervention—even as deterministic treatments of systems as simple as the three body problem in gravitation remained intractable.[29]

British work, carried on by mathematicians such as Brook Taylor and Colin Maclaurin, fell behind Continental developments as the century progressed. Meanwhile, work flourished at scientific academies on the Continent, led by such mathematicians as Daniel Bernoulli, Leonhard Euler, Joseph-Louis Lagrange, Pierre-Simon Laplace, and Adrien-Marie Legendre. At the end of the century, the members of the French Academy of Sciences had attained clear dominance in the field.[30][31][32][33]

Physical experimentation in the 18th and early 19th centuries

At the same time, the experimental tradition established by Galileo and his followers persisted. The Royal Society and the French Academy of Sciences were major centers for the performance and reporting of experimental work, and Newton was himself an influential experimenter, particularly in the field of optics, where he was recognized for his prism experiments dividing white light into its constituent spectrum of colors, as published in his 1704 book Opticks (which also advocated a particulate interpretation of light). Experiments in mechanics, optics, magnetism, static electricity, chemistry, and physiology were not clearly distinguished from each other during the 18th century, but significant differences in explanatory schemes and, thus, experiment design were emerging. Chemical experimenters, for instance, defied attempts to enforce a scheme of abstract Newtonian forces onto chemical affiliations, and instead focused on the isolation and classification of chemical substances and reactions.[34]

Nevertheless, the separate fields remained tied together, most clearly through the theories of weightless “imponderable fluids", such as heat (“caloric”), electricity, and phlogiston (which was rapidly overthrown as a concept following Lavoisier’s identification of oxygen gas late in the century). Assuming that these concepts were real fluids, their flow could be traced through a mechanical apparatus or chemical reactions. This tradition of experimentation led to the development of new kinds of experimental apparatus, such as the Leyden Jar and the Voltaic Pile; and new kinds of measuring instruments, such as the calorimeter, and improved versions of old ones, such as the thermometer. Experiments also produced new concepts, such as the University of Glasgow experimenter Joseph Black’s notion of latent heat and Philadelphia intellectual Benjamin Franklin’s characterization of electrical fluid as flowing between places of excess and deficit (a concept later reinterpreted in terms of positive and negative charges).

Michael Faraday (1791-1867) delivering the 1856 Christmas Lecture at the Royal Institution.

While it was recognized early in the 18th century that finding absolute theories of electrostatic and magnetic force akin to Newton’s principles of motion would be an important achievement, none were forthcoming. This impossibility only slowly disappeared as experimental practice became more widespread and more refined in the early years of the 19th century in places such as the newly-established Royal Institution in London, where John Dalton argued for an atomistic interpretation of chemistry, Thomas Young argued for the interpretation of light as a wave, and Michael Faraday established the phenomenon of electromagnetic induction. Meanwhile, the analytical methods of rational mechanics began to be applied to experimental phenomena, most influentially with the French mathematician Joseph Fourier’s analytical treatment of the flow of heat, as published in 1822.[35][36][37]

Thermodynamics, statistical mechanics, and electromagnetic theory

William Thomson (1824-1907), later Lord Kelvin

The establishment of a mathematical physics of energy between the 1850s and the 1870s expanded substantially on the physics of prior eras and challenged traditional ideas about how the physical world worked. While Pierre-Simon Laplace’s work on celestial mechanics solidified a deterministically mechanistic view of objects obeying fundamental and totally reversible laws, the study of energy and particularly the flow of heat, threw this view of the universe into question. Drawing upon the engineering theory of Lazare and Sadi Carnot, and Émile Clapeyron; the experimentation of James Prescott Joule on the interchangeability of mechanical, chemical, thermal, and electrical forms of work; and his own Cambridge mathematical tripos training in mathematical analysis; the Glasgow physicist William Thomson and his circle of associates established a new mathematical physics relating to the exchange of different forms of energy and energy’s overall conservation (what is still accepted as the “first law of thermodynamics”). Their work was soon allied with the theories of similar but less-known work by the German physician Julius Robert von Mayer and physicist and physiologist Hermann von Helmholtz on the conservation of forces.

Ludwig Boltzmann (1844-1906)

Taking his mathematical cues from the heat flow work of Joseph Fourier (and his own religious and geological convictions), Thomson believed that the dissipation of energy with time (what is accepted as the “second law of thermodynamics”) represented a fundamental principle of physics, which was expounded in Thomson and Peter Guthrie Tait’s influential work Treatise on Natural Philosophy. However, other interpretations of what Thomson called thermodynamics were established through the work of the German physicist Rudolf Clausius. His statistical mechanics, which was elaborated upon by Ludwig Boltzmann and the British physicist James Clerk Maxwell, held that energy (including heat) was a measure of the speed of particles. Interrelating the statistical likelihood of certain states of organization of these particles with the energy of those states, Clausius reinterpreted the dissipation of energy to be the statistical tendency of molecular configurations to pass toward increasingly likely, increasingly disorganized states (coining the term “entropy” to describe the disorganization of a state). The statistical versus absolute interpretations of the second law of thermodynamics set up a dispute that would last for several decades (producing arguments such as “Maxwell's demon”), and that would not be held to be definitively resolved until the behavior of atoms was firmly established in the early 20th century.[38][39]

Meanwhile, the new physics of energy transformed the analysis of electromagnetic phenomena, particularly through the introduction of the concept of the field and the publication of Maxwell’s 1873 Treatise on Electricity and Magnetism, which also drew upon theoretical work by German theoreticians such as Carl Friedrich Gauss and Wilhelm Weber. The encapsulation of heat in particulate motion, and the addition of electromagnetic forces to Newtonian dynamics established an enormously robust theoretical underpinning to physical observations. The prediction that light represented a transmission of energy in wave form through a “luminiferous ether”, and the seeming confirmation of that prediction with Helmholtz student Heinrich Hertz’s 1888 detection of electromagnetic radiation, was a major triumph for physical theory and raised the possibility that even more fundamental theories based on the field could soon be developed.[40][41][42][43] Research on the transmission of electromagnetic waves began soon after, with the experiments conducted by physicists such as Nikola Tesla, Jagadish Chandra Bose and Guglielmo Marconi during the 1890s leading to the invention of radio.

The emergence of a new physics circa 1900

File:Marie Curie (Nobel-physics).png
Marie Skłodowska Curie (1867-1934)

The triumph of Maxwell’s theories was undermined by inadequacies that had already begun to appear. The Michelson-Morley experiment failed to detect a shift in the speed of light, which would have been expected as the earth moved at different angles with respect to the ether. The possibility explored by Hendrik Lorentz, that the ether could compress matter, thereby rendering it undetectable, presented problems of its own as a compressed electron (detected in 1897 by British experimentalist J. J. Thomson) would prove unstable. Meanwhile, other experimenters began to detect unexpected forms of radiation: Wilhelm Röntgen caused a sensation with his discovery of x-rays in 1895; in 1896 Henri Becquerel discovered that certain kinds of matter emit radiation on their own accord. Marie and Pierre Curie coined the term “radioactivity” to describe this property of matter, and isolated the radioactive elements radium and polonium. Ernest Rutherford and Frederick Soddy identified two of Becquerel’s forms of radiation with electrons and the element helium. In 1911 Rutherford established that the bulk of mass in atoms are concentrated in positively-charged nuclei with orbiting electrons, which was a theoretically unstable configuration. Studies of radiation and radioactive decay continued to be a preeminent focus for physical and chemical research through the 1930s, when the discovery of nuclear fission opened the way to the practical exploitation of what came to be called “atomic” energy.

Albert Einstein (1879-1955)

Radical new physical theories also began to emerge in this same period. In 1905 Albert Einstein, then a Bern patent clerk, argued that the speed of light was a constant in all inertial reference frames and that electromagnetic laws should remain valid independent of reference frame—assertions which rendered the ether “superfluous” to physical theory, and that held that observations of time and length varied relative to how the observer was moving with respect to the object being measured (what came to be called the “special theory of relativity”). It also followed that mass and energy were interchangeable quantities according to the equation E=mc2. In another paper published the same year, Einstein asserted that electromagnetic radiation was transmitted in discrete quantities (“quanta”), according to a constant that the theoretical physicist Max Planck had posited in 1900 to arrive at an accurate theory for the distribution of blackbody radiation—an assumption that explained the strange properties of the photoelectric effect. The Danish physicist Niels Bohr used this same constant in 1913 to explain the stability of Rutherford’s atom as well as the frequencies of light emitted by hydrogen gas.

The radical years: general relativity and quantum mechanics

The gradual acceptance of Einstein’s theories of relativity and the quantized nature of light transmission, and of Niels Bohr’s model of the atom created as many problems as they solved, leading to a full-scale effort to reestablish physics on new fundamental principles. Expanding relativity to cases of accelerating reference frames (the “general theory of relativity”) in the 1910s, Einstein posited an equivalence between the inertial force of acceleration and the force of gravity, leading to the conclusion that space is curved and finite in size, and the prediction of such phenomena as gravitational lensing and the distortion of time in gravitational fields.

Niels Bohr (1885-1962)

The quantized theory of the atom gave way to a full-scale quantum mechanics in the 1920s. The quantum theory (which previously relied in the “correspondence” at large scales between the quantized world of the atom and the continuities of the “classical” world) was accepted when the Compton Effect established that light carries momentum and can scatter off particles, and when Louis de Broglie asserted that matter can be seen as behaving as a wave in much the same way as electromagnetic waves behave like particles (wave-particle duality). New principles of a “quantum” rather than a “classical” mechanics, formulated in matrix-form by Werner Heisenberg, Max Born, and Pascual Jordan in 1925, were based on the probabilistic relationship between discrete “states” and denied the possibility of causality. Erwin Schrödinger established an equivalent theory based on waves in 1926; but Heisenberg’s 1927 “uncertainty principle” (indicating the impossibility of precisely and simultaneously measuring position and momentum) and the “Copenhagen interpretation” of quantum mechanics (named after Bohr’s home city) continued to deny the possibility of fundamental causality, though opponents such as Einstein would assert that “God does not play dice with the universe”.[44] Also in the 1920s, Satyendra Nath Bose's work on photons and quantum mechanics provided the foundation for Bose-Einstein statistics, the theory of the Bose-Einstein condensate, and the discovery of the boson.

Constructing a new fundamental physics

A “Feynman diagram” of a renormalized vertex in quantum electrodynamics.

As the philosophically inclined continued to debate the fundamental nature of the universe, quantum theories continued to be produced, beginning with Paul Dirac’s formulation of a relativistic quantum theory in 1927. However, attempts to quantize electromagnetic theory entirely were stymied throughout the 1930s by theoretical formulations yielding infinite energies. This situation was not considered adequately resolved until after World War II ended, when Julian Schwinger, Richard Feynman, and Sin-Itiro Tomonaga independently posited the technique of “renormalization”, which allowed for an establishment of a robust quantum electrodynamics (Q.E.D.).[45]

Meanwhile, new theories of fundamental particles proliferated with the rise of the idea of the quantization of fields through “exchange forces” regulated by an exchange of short-lived “virtual” particles, which were allowed to exist according to the laws governing the uncertainties inherent in the quantum world. Notably, Hideki Yukawa proposed that the positive charges of the nucleus were kept together courtesy of a powerful but short-range force mediated by a particle intermediate in mass between the size of an electron and a proton. This particle, called the “pion”, was identified in 1947, but it was part of a slew of particle discoveries beginning with the neutron, the “positron” (a positively-charged “antimatter” version of the electron), and the “muon” (a heavier relative to the electron) in the 1930s, and continuing after the war with a wide variety of other particles detected in various kinds of apparatus: cloud chambers, nuclear emulsions, bubble chambers, and coincidence counters. At first these particles were found primarily by the ionized trails left by cosmic rays, but were increasingly produced in newer and more powerful particle accelerators.[46]

File:First Gold Beam-Beam Collision Events at RHIC at 100 100 GeV c per beam recorded by STAR.jpg
Thousands of particles explode from the collision point of two relativistic (100 GeV per ion) gold ions in the STAR detector of the Relativistic Heavy Ion Collider; an experiment done in order to investigate the properties of a quark gluon plasma such as the one thought to exist in the ultrahot first few microseconds after the big bang

The interaction of these particles by “scattering” and “decay” provided a key to new fundamental quantum theories. Murray Gell-Mann and Yuval Ne'eman brought some order to these new particles by classifying them according to certain qualities, beginning with what Gell-Mann referred to as the “Eightfold Way”, but proceeding into several different “octets” and “decuplets” which could predict new particles, most famously the
Ω
, which was detected at Brookhaven National Laboratory in 1964, and which gave rise to the “quark” model of hadron composition. While the quark model at first seemed inadequate to describe strong nuclear forces, allowing the temporary rise of competing theories such as the S-Matrix, the establishment of quantum chromodynamics in the 1970s finalized a set of fundamental and exchange particles, which allowed for the establishment of a “standard model” based on the mathematics of gauge invariance, which successfully described all forces except for gravity, and which remains generally accepted within the domain to which it is designed to be applied.[47]

The “standard model” groups the electroweak interaction theory and quantum chromodynamics into a structure denoted by the gauge group SU(3)×SU(2)×U(1). The formulation of the unification of the electromagnetic and weak interactions in the standard model is due to Abdus Salam, Steven Weinberg and, subsequently, Sheldon Glashow. After the discovery, made at CERN, of the existence of neutral weak currents,[48][49][50][51] mediated by the
Z
boson
foreseen in the standard model, the physicists Salam, Glashow and Weinberg received the 1979 Nobel Prize in Physics for their electroweak theory.[52]

While accelerators have confirmed most aspects of the standard model by detecting expected particle interactions at various collision energies, no theory reconciling the general theory of relativity with the standard model has yet been found, although “string theory” has provided one promising avenue forward. Since the 1970s, fundamental particle physics has provided insights into early universe cosmology, particularly the “big bang” theory proposed as a consequence of Einstein’s general theory. However, starting from the 1990s, astronomical observations have also provided new challenges, such as the need for new explanations of galactic stability (the problem of dark matter), and accelerating expansion of the universe (the problem of dark energy).

The physical sciences

With increased accessibility to and elaboration upon advanced analytical techniques in the 19th century, physics was defined as much, if not more, by those techniques than by the search for universal principles of motion and energy, and the fundamental nature of matter. Fields such as acoustics, geophysics, astrophysics, aerodynamics, plasma physics, low-temperature physics, and solid-state physics joined optics, fluid dynamics, electromagnetism, and mechanics as areas of physical research. In the 20th century, physics also became closely allied with such fields as electrical, aerospace, and materials engineering, and physicists began to work in government and industrial laboratories as much as in academic settings. Following World War II, the population of physicists increased dramatically, and came to be centered on the United States, while, in more recent decades, physics has become a more international pursuit than at any time in its previous history.

See also

Further reading

  • “Selected Works about Isaac Newton and His Thought” from The Newton Project.
  • Dear, Peter (2001), Revolutionizing the Sciences: European Knowledge and Its Ambitions, 1500-1700, Princeton: Princeton University Press, ISBN 0691088594, OCLC 46622656.
  • Nye, Mary Jo (1996), Before Big Science: The Pursuit of Modern Chemistry and Physics, 1800-1940, New York: Twayne, ISBN 080579512X, OCLC 185866968 34878783 {{citation}}: Check |oclc= value (help).
  • Segrè, Emilio (1984), From Falling Bodies to Radio Waves: Classical Physicists and Their Discoveries, New York: W. H. Freeman, ISBN 0-7167-1482-5, OCLC 9943504.
  • Segrè, Emilio (1980), From X-Rays to Quarks: Modern Physicists and Their Discoveries, San Francisco: W. H. Freeman, ISBN 0-7167-1147-8, OCLC 237246197 56100286 5946636 {{citation}}: Check |oclc= value (help).
  • Nina Byers and Gary Williams, ed., OUT OF THE SHADOWS:Contributions of 20th Century Women to Physics Cambridge University Press, 2006 ISBN 0-5218-2197-1

Notes

  1. ^ Dear (1995)
  2. ^ Glick, Livesey & Wallis (2005, p. 89-90)
  3. ^ Mariam Rozhanskaya and I. S. Levinova (1996), "Statics", p. 642, in Rashed & Morelon (1996, pp. 614–642):

    "Using a whole body of mathematical methods (not only those inherited from the antique theory of ratios and infinitesimal techniques, but also the methods of the contemporary algebra and fine calculation techniques), Arabic scientists raised statics to a new, higher level. The classical results of Archimedes in the theory of the centre of gravity were generalized and applied to three-dimensional bodies, the theory of ponderable lever was founded and the 'science of gravity' was created and later further developed in medieval Europe. The phenomena of statics were studied by using the dynamic approach so that two trends - statics and dynamics - turned out to be inter-related within a single science, mechanics."

    "The combination of the dynamic approach with Archimedean hydrostatics gave birth to a direction in science which may be called medieval hydrodynamics."

    "Archimedean statics formed the basis for creating the fundamentals of the science on specific weight. Numerous fine experimental methods were developed for determining the specific weight, which were based, in particular, on the theory of balances and weighing. The classical works of al-Biruni and al-Khazini can by right be considered as the beginning of the application of experimental methods in medieval science."

    "Arabic statics was an essential link in the progress of world science. It played an important part in the prehistory of classical mechanics in medieval Europe. Without it classical mechanics proper could probably not have been created."

  4. ^ Smith (1996, p. x)
  5. ^ Smith (1996, p. 18)
  6. ^ Smith (1996, p. 19)
  7. ^ Tybjerg (2002, p. 350)
  8. ^ a b Thiele (2005a):

    “Through a closer examination of Ibn al-Haytham's conceptions of mathematical models and of the role they play in his theory of sense perception, it becomes evident that he was the true founder of physics in the modern sense of the word; in fact he anticipated by six centuries the fertile ideas that were to mark the beginning of this new branch of science.”

  9. ^ a b Thiele (2005b):

    "Schramm showed that already some centuries before Galileo, experimental physics had its roots in Ibn al-Haytham."

  10. ^ a b c Toomer (1964)
  11. ^ a b Sabra (2003, pp. 91–2)
  12. ^ Rashed & Armstrong (1994, pp. 345–6)
  13. ^ a b Smith (1996, p. 57)
  14. ^ Rashed (2007, p. 19):

    "In reforming optics he as it were adopted ‘‘positivism’’ (before the term was invented): we do not go beyond experience, and we cannot be content to use pure concepts in investigating natural phenomena. Understanding of these cannot be acquired without mathematics. Thus, once he has assumed light is a material substance, Ibn al-Haytham does not discuss its nature further, but confines himself to considering its propagation and diffusion. In his optics ‘‘the smallest parts of light’’, as he calls them, retain only properties that can be treated by geometry and verified by experiment; they lack all sensible qualities except energy."

  15. ^ Sabra (1998, p. 300)
  16. ^ a b Gorini (2003):

    "According to the majority of the historians al-Haytham was the pioneer of the modern scientific method. With his book he changed the meaning of the term optics and established experiments as the norm of proof in the field. His investigations are based not on abstract theories, but on experimental evidences and his experiments were systematic and repeatable."

  17. ^ G. A. Russell, "Emergence of Physiological Optics", pp. 686-7, in Rashed & Morelon (1996)
  18. ^ Sabra (1989)
  19. ^ (Dijksterhuis 2004, pp. 113–5):

    "Through the influential work of Alhacen the onset of a physico-mathematical conception of optics was established at a much earlier time than would be the case in the other mathematical sciences."

  20. ^ Drake (1978)
  21. ^ Biagioli (1993)
  22. ^ Shea (1991)
  23. ^ Garber (1992)
  24. ^ Gaukroger (2002)
  25. ^ Hall (1980)
  26. ^ Bertolini Meli (1993)
  27. ^ Guicciardini (1999)
  28. ^ Darrigol (2005)
  29. ^ Bos (1980)
  30. ^ Greenberg (1986)
  31. ^ Guicciardini (1989)
  32. ^ Guicciardini (1999)
  33. ^ Garber (1999)
  34. ^ Ben-Chaim (2004)
  35. ^ Heilbron (1979)
  36. ^ Buchwald (1989)
  37. ^ Golinski (1999)
  38. ^ Smith & Wise (1989)
  39. ^ Smith (1998)
  40. ^ Buchwald (1985)
  41. ^ Jungnickel and McCormmanch (1986)
  42. ^ Hunt (1991)
  43. ^ Buchwald (1994)
  44. ^ Kragh (1999)
  45. ^ Schweber (1994)
  46. ^ Galison (1997)
  47. ^ Kragh (1999)
  48. ^ F. J. Hasert et al. Phys. Lett. 46B 121 (1973).
  49. ^ F. J. Hasert et al. Phys. Lett. 46B 138 (1973).
  50. ^ F. J. Hasert et al. Nucl. Phys. B73 1(1974).
  51. ^ "The discovery of the weak neutral currents". CERN courier. 2004-10-04. Retrieved 2008-05-08.
  52. ^ "The Nobel Prize in Physics 1979". Nobel Foundation. Retrieved 2008-09-10.

References

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  • Bertolini Meli, Domenico (1993), Equivalence and Priority: Newton versus Leibniz, New York: Oxford University Press.
  • Biagioli, Mario (1993), Galileo, Courtier: The Practice of Science in the Culture of Absolutism, Chicago: University of Chicago Press, ISBN 0226045595, OCLC 185632037 26767743 {{citation}}: Check |oclc= value (help).
  • Bos, Henk (1980), "Mathematics and Rational Mechanics", in Rousseau, G. S.; Porter, Roy (eds.), The Ferment of Knowledge: Studies in the Historiography of Eighteenth Century Science, New York: Cambridge University Press.
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