Misplaced Pages

#145854

130-435: Augustin-Jean Fresnel (10 May 1788 – 14 July 1827) was a French civil engineer and physicist whose research in optics led to the almost unanimous acceptance of the wave theory of light , excluding any remnant of Newton 's corpuscular theory , from the late 1830s  until the end of the 19th century. He is perhaps better known for inventing the catadioptric (reflective/refractive) Fresnel lens and for pioneering

260-700: A master's degree like MSc, MPhil, MPhys or MSci. For research-oriented careers, students work toward a doctoral degree specializing in a particular field. Fields of specialization include experimental and theoretical astrophysics , atomic physics , biological physics , chemical physics , condensed matter physics , cosmology , geophysics , gravitational physics , material science , medical physics , microelectronics , molecular physics , nuclear physics , optics , particle physics , plasma physics , quantum information science , and radiophysics . The three major employers of career physicists are academic institutions, laboratories, and private industries, with

390-556: A Jansenist. He regarded his intellectual talents as gifts from God, and considered it his duty to use them for the benefit of others. According to his fellow engineer Alphonse Duleau, who helped to nurse him through his final illness, Fresnel saw the study of nature as part of the study of the power and goodness of God. He placed virtue above science and genius. In his last days he prayed for "strength of soul," not against death alone, but against "the interruption of discoveries… of which he hoped to derive useful applications."  Jansenism

520-427: A chance to acquire the items on his reading lists, with the apparent exception of "Young's book", which he could not understand without his brother's help.  Not surprisingly, he had retraced many of Young's steps. In a memoir sent to the institute on 15 October 1815, Fresnel mapped the external and internal fringes in the shadow of a wire. He noticed, like Young before him, that the internal fringes disappeared when

650-595: A characteristic shared with the Channel Islands. The Channel Islands are considered culturally and historically a part of Normandy. However, they are British Crown Dependencies , and are not part of the modern French administrative region of Normandy . Although the British surrendered claims to mainland Normandy, France, and other French possessions in 1801, the monarch of the United Kingdom retains

780-619: A constant use of Old Norse during four or five generations in certain parts of Normandy. They then became the Normans – a Norman French -speaking mixture of Norsemen and indigenous Gallo-Franks. Rollo's descendant William became king of England in 1066 after defeating Harold Godwinson , the last of the Anglo-Saxon kings , at the Battle of Hastings , while retaining the fiefdom of Normandy for himself and his descendants. Aside from

910-412: A frequency proportional to that of Newton's "fits", due to forces depending on the alignment. This theory became known as mobile polarization . To reconcile his results with a sinusoidal oscillation, Biot had to suppose that the corpuscles emerged with one of two permitted orientations, namely the extremes of the oscillation, with probabilities depending on the phase of the oscillation. Corpuscular optics

1040-450: A manner rather analogous to the one you have adopted. But what neither he nor anyone had seen before you is that the external colored bands do not travel in a straight line as one moves away from the opaque body. The results you have achieved in this regard seem to me very important; perhaps they can serve to prove the truth of the undulatory system, so often and so feebly combated by physicists who have not bothered to understand it. Fresnel

1170-452: A minimum, the owner must possess a three-year bachelors or equivalent degree in physics or a related field and an additional minimum of six years' experience in a physics-related activity; or an Honor or equivalent degree in physics or a related field and an additional minimum of five years' experience in a physics-related activity; or master or equivalent degree in physics or a related field and an additional minimum of three years' experience in

1300-565: A physics-related activity; a Doctorate or equivalent degree in Physics or a related field; or training or experience which, in the opinion of the Council, is equivalent to any of the above. Physicists may be a member of a physical society of a country or region. Physical societies commonly publish scientific journals, organize physics conferences and award prizes for contributions to the field of physics. Some examples of physical societies are

1430-416: A professional practice examination must also be passed. An exemption can be granted to a candidate that has practiced physics for at least seven years and provide a detailed description of their professional accomplishments which clearly demonstrate that the exam is not necessary. Work experience will be considered physics-related if it uses physics directly or significantly uses the modes of thought (such as

SECTION 10

#1732766021146

1560-559: A public celebrity in his lifetime, he lived just long enough to receive due recognition from his peers, including (on his deathbed) the Rumford Medal of the Royal Society of London , and his name is ubiquitous in the modern terminology of optics and waves. After the wave theory of light was subsumed by Maxwell 's electromagnetic theory in the 1860s, some attention was diverted from the magnitude of Fresnel's contribution. In

1690-421: A ray of light is reflected off a non-metallic surface at the appropriate angle, it behaves like one of the two rays emerging from a calcite crystal. It was Malus who coined the term polarization to describe this behavior, although the polarizing angle became known as Brewster's angle after its dependence on the refractive index was determined experimentally by David Brewster in 1815. Malus also introduced

1820-467: A separate phenomenon, and produced evidence that diffraction fringes inside the shadow of a narrow obstacle were due to interference: when the light from one side was blocked, the internal fringes disappeared. But Young was alone in such efforts until Fresnel entered the field. Huygens, in his investigation of double refraction, noticed something that he could not explain: when light passes through two similarly oriented calcite crystals at normal incidence,

1950-422: A time. Only the corpuscular theory gave even a vague insight into Brewster's angle, Malus's law, or optical rotation. Concerning chromatic polarization, the wave theory explained the periodicity far better than the corpuscular theory, but had nothing to say about the role of polarization; and its explanation of the periodicity was largely ignored. And Arago had founded the study of chromatic polarization, only to lose

2080-410: Is Charles III and each have an appointed Lieutenant-Governor . The Bailiwick of Guernsey comprises three separate jurisdictions: Guernsey , Alderney and Sark . Administratively, Herm forms part of Guernsey . Much of Normandy is predominantly agricultural in character, with cattle breeding the most important sector (although in decline from the peak levels of the 1970s and 1980s). The bocage

2210-655: Is a patchwork of small fields with high hedges, typical of western areas. Areas near the Seine (the former Upper Normandy region) contain a higher concentration of industry. Normandy is a significant cider -producing region, and also produces calvados , a distilled cider or apple brandy . Other activities of economic importance are dairy produce, flax (60% of production in France), horse breeding (including two French national stud farms), fishing, seafood, and tourism. The region contains three French nuclear power stations . There

2340-573: Is also easy access to and from the UK using the ports of Cherbourg , Caen ( Ouistreham ), Le Havre and Dieppe . Jersey and Guernsey are often considered to be tax havens, due to having large financial services sectors and low tax rates. In January 2006 the population of French Normandy (including the part of Perche which lies inside the Orne département but excluding the Channel Islands )

2470-705: Is based on an intellectual ladder of discoveries and insights from ancient times to the present. Many mathematical and physical ideas used today found their earliest expression in the work of ancient civilizations, such as the Babylonian astronomers and Egyptian engineers , the Greek philosophers of science and mathematicians such as Thales of Miletus , Euclid in Ptolemaic Egypt , Archimedes of Syracuse and Aristarchus of Samos . Roots also emerged in ancient Asian cultures such as India and China, and particularly

2600-623: Is considered heretical by the Roman Catholic Church, and Grattan-Guinness suggests this is why Fresnel never gained a permanent academic teaching post; his only teaching appointment was at the Athénée in the winter of 1819–20. The article on Fresnel in the Catholic Encyclopedia does not mention his Jansenism, but describes him as "a deeply religious man and remarkable for his keen sense of duty."  Fresnel

2730-584: Is regardless still sometimes informally referred to by the title "Duke of Normandy". The historical Duchy of Normandy was a formerly independent duchy occupying the lower Seine area, the Pays de Caux and the region to the west through the Pays d'Auge as far as the Cotentin Peninsula and Channel Islands. Western Normandy belongs to the Armorican Massif , while most of the region lies in

SECTION 20

#1732766021146

2860-615: Is the Nobel Prize in Physics , awarded since 1901 by the Royal Swedish Academy of Sciences . National physical societies have many prizes and awards for professional recognition. In the case of the American Physical Society , as of 2023, there are 25 separate prizes and 33 separate awards in the field. Chartered Physicist (CPhys) is a chartered status and a professional qualification awarded by

2990-578: The American Physical Society , the Institute of Physics , with the oldest physical society being the German Physical Society . Normandy Normandy (French: Normandie ; Norman : Normaundie or Nouormandie ) is a geographical and cultural region in northwestern Europe, roughly coextensive with the historical Duchy of Normandy . Normandy comprises mainland Normandy (a part of France) and insular Normandy (mostly

3120-643: The British Isles , and often turned the women into frilla , a Scandinavian tradition which became known as more Danico , medieval Latin meaning "Danish marriage". The first counts of Rouen and the dukes of Normandy had concubines too. While very little archeological excavations about the Vikings were done in Normandy, the Norman toponymy retains a large Scandinavian and Anglo-Scandinavian heritage, due to

3250-696: The Bronze Age . When Julius Caesar invaded Gaul (58–50 BC), there were nine different Celtic tribes living in this part of Gaul. The Romanisation of this region partly included in the Gallia Celtica and in the Gallia Belgica (the Seine being more or less the limit between them) was achieved by the usual methods: Roman roads and a policy of urbanisation. Classicists mention many Gallo-Roman villas and archeology found their traces in

3380-608: The French Revolutionary Wars and the Napoleonic Wars (1792–1815), there was an economic revival that included the mechanization of textile manufacturing and the introduction of the first trains. Also, with seaside tourism in the 19th century came the advent of the first beach resorts. During the Second World War, following the armistice of 22 June 1940 , continental Normandy was part of

3510-564: The German occupied zone of France . The Channel Islands were occupied by German forces between 30 June 1940 and 9 May 1945. The town of Dieppe was the site of the unsuccessful Dieppe Raid by Allied forces. The Allies coordinated a massive build-up of troops and supplies to support a large-scale invasion of Normandy in the D-Day landings on 6 June 1944 under the code name Operation Overlord . German forces dug into fortified emplacements above

3640-697: The Institute of Physics . It is denoted by the postnominals "CPhys". Achieving chartered status in any profession denotes to the wider community a high level of specialised subject knowledge and professional competence. According to the Institute of Physics, holders of the award of the Chartered Physicist (CPhys) demonstrate the "highest standards of professionalism, up-to-date expertise, quality and safety" along with "the capacity to undertake independent practice and exercise leadership" as well as "commitment to keep pace with advancing knowledge and with

3770-548: The Islamic medieval period , which saw the development of scientific methodology emphasising experimentation , such as the work of Ibn al-Haytham (Alhazen) in the 11th century. The modern scientific worldview and the bulk of physics education can be said to flow from the scientific revolution in Europe, starting with the work of astronomer Nicolaus Copernicus leading to the physics of Galileo Galilei and Johannes Kepler in

3900-545: The Jansenist sect, characterized by an extreme Augustinian view of original sin . Religion took first place in the boys' home-schooling. In 1802, his mother said: I pray God to give my son the grace to employ the great talents, which he has received, for his own benefit, and for the God of all. Much will be asked from him to whom much has been given, and most will be required of him who has received most. Augustin remained

4030-559: The Mississippi Delta were opened up to establish Canada and Louisiana . Colonists from Normandy were among the most active in New France , comprising Acadia , Canada, and Louisiana. Honfleur and Le Havre were two of the principal slave trade ports of France. Although agriculture remained important, industries such as weaving, metallurgy, sugar refining, ceramics, and shipbuilding were introduced and developed. In

Augustin-Jean Fresnel - Misplaced Pages Continue

4160-670: The Paris Basin . France's oldest rocks are exposed in Jobourg, on the Cotentin peninsula. The region is bounded to the north and west by the English Channel . There are granite cliffs in the west and limestone cliffs in the east. There are also long stretches of beach in the centre of the region. The bocage typical of the western areas caused problems for the invading forces in the Battle of Normandy . A notable feature of

4290-692: The Wars of Religion . When many Norman towns ( Alençon , Rouen, Caen , Coutances , Bayeux ) joined the Protestant Reformation , battles ensued throughout the province. In the Channel Islands, a period of Calvinism following the Reformation was suppressed when Anglicanism was imposed following the Stuart Restoration . Samuel de Champlain left the port of Honfleur in 1604 and founded Acadia . Four years later, he founded

4420-492: The chemistry of painting. He became the Permanent Secretary of the École des Beaux-Arts and (until 1814) a professor at the École Polytechnique, and was the initial point of contact between Augustin and the leading optical physicists of the day (see below ) . The Fresnel brothers were initially home-schooled by their mother. The sickly Augustin was considered the slow one, not inclined to memorization; but

4550-415: The external fringes of a shadow; but, as he later explained, that was because Newton had already done so. Newton evidently thought the fringes were caustics . Thus Arago erred in his belief that the curved paths of the fringes were fundamentally incompatible with the corpuscular theory. Arago's letter went on to request more data on the external fringes. Fresnel complied, until he exhausted his leave and

4680-688: The regional elections in December 2015 . The Regional Council has 102 members who are elected under a system of proportional representation . The executive consists of a president and vice-presidents. Hervé Morin from the Centre party was elected president of the council in January 2016. The Channel Islands are not part of French territory, but are instead British Crown Dependencies . They are self-governing, each having its own parliament, government and legal system. The head of state of both territories

4810-527: The saturation (not the hue) of the colors. This phenomenon became known as chromatic polarization . Replacing the mica with a much thicker plate of quartz , with its faces perpendicular to the optic axis (the axis of Huygens's spheroid or Malus's velocity function), produced a similar effect, except that rotating the quartz made no difference. Arago tried to explain his observations in corpuscular terms. In 1812, as Arago pursued further qualitative experiments and other commitments, Jean-Baptiste Biot reworked

4940-496: The École Nationale des Ponts et Chaussées (National School of Bridges and Roads, also known as "ENPC" or "École des Ponts"), from which he graduated in 1809, entering the service of the Corps des Ponts et Chaussées as an ingénieur ordinaire aspirant (ordinary engineer in training). Directly or indirectly, he was to remain in the employment of the "Corps des Ponts" for the rest of his life. Fresnel's parents were Roman Catholics of

5070-578: The 10th century between King Charles III of France and the Viking jarl Rollo . For almost 150 years following the Norman conquest of England in 1066, Normandy and England were linked by having the same person reign as both Duke of Normandy and King of England . Archaeological finds, such as cave paintings , prove that humans were present in the region in prehistoric times. Normandy also has many megalithic monuments . Celts (also known as Belgae and Gauls ) have populated Normandy since at least

5200-591: The 1780s, the economic crisis and the crisis of the Ancien Régime struck Normandy as well as other parts of the nation, leading to the French Revolution . Bad harvests, technical progress and the effects of the Eden Agreement signed in 1786 affected employment and the economy of the province. Normans laboured under a heavy fiscal burden. In 1790, the five departments of Normandy replaced

5330-579: The 19th century. Many physicists contributed to the development of quantum mechanics in the early-to-mid 20th century. New knowledge in the early 21st century includes a large increase in understanding physical cosmology . The broad and general study of nature, natural philosophy , was divided into several fields in the 19th century, when the concept of "science" received its modern shape. Specific categories emerged, such as "biology" and "biologist", "physics" and "physicist", "chemistry" and "chemist", among other technical fields and titles. The term physicist

Augustin-Jean Fresnel - Misplaced Pages Continue

5460-522: The British Channel Islands ). It covers 30,627 square kilometres (11,825 sq mi). Its population in 2017 was 3,499,280. The inhabitants of Normandy are known as Normans ; the region is the historic homeland of the Norman language . Large settlements include Rouen , Caen , Le Havre and Cherbourg . The cultural region of Normandy is roughly similar to the historical Duchy of Normandy, which includes small areas now part of

5590-400: The Channel Islands and England. Jersey and Guernsey use three leopards in their national symbols. The leopards represents the strength and courage Normandy has towards the neighbouring provinces. The unofficial anthem of the region is the song " Ma Normandie ". The Norman language, including its insular variations Jèrriais and Guernésiais , is a regional language , spoken by a minority of

5720-748: The City of Québec. From then onwards, Normans engaged in a policy of expansion in North America. They continued the exploration of the New World: René-Robert Cavelier de La Salle travelled in the area of the Great Lakes , then on the Mississippi River . Pierre Le Moyne d'Iberville and his brother Lemoyne de Bienville founded Louisiana , Biloxi , Mobile and New Orleans. Territories located between Québec and

5850-521: The French Académie des Sciences and other académies in 1795. In 1816 the Académie des Sciences regained its name and autonomy, but remained part of the institute.) In March 1815, perceiving Napoleon's return from Elba as "an attack on civilization", Fresnel departed without leave, hastened to Toulouse and offered his services to the royalist resistance, but soon found himself on

5980-892: The Great Count progressively claimed territories in southern Italy until founding the Kingdom of Sicily in 1130. They also carved out a place for themselves and their descendants in the Crusader states of Asia Minor and the Holy Land . The 14th-century explorer Jean de Béthencourt established a kingdom in the Canary Islands in 1404. He received the title King of the Canary Islands from Pope Innocent VII but recognized Henry III of Castile as his overlord, who had provided him with military and financial aid during

6110-552: The Lighthouse Commission, and helped to edit his collected works. The fourth, Fulgence Fresnel , became a linguist, diplomat, and orientalist, and occasionally assisted Augustin with negotiations. Fulgence died in Bagdad in 1855 having led a mission to explore Babylon. Madame Fresnel's younger brother, Jean François "Léonor" Mérimée , father of the writer Prosper Mérimée , was a painter who turned his attention to

6240-503: The advocates of the undulatory theory than any other facts with which we are acquainted."  Malus died in February 1812, at the age of 36, shortly after receiving the Rumford Medal for his work on polarization. In August 1811, François Arago reported that if a thin plate of mica was viewed against a white polarized backlight through a calcite crystal, the two images of the mica were of complementary colors (the overlap having

6370-399: The approach to problem-solving) developed in your education or experience as a physicist, in all cases regardless of whether the experience is in academia, industry, government, or elsewhere. Management of physics-related work qualifies, and so does appropriate graduate student work. The South African Institute of Physics also delivers a certification of Professional Physicist (Pr.Phys). At

6500-466: The area between the rivers Somme and Loire came under the control of the Frankish lord Clovis . Vikings started to raid along the river Seine during the middle of the 9th century. As early as 841, a Viking fleet appeared at the mouth of the Seine, the principal route by which they entered the kingdom. After attacking and destroying monasteries, including one at Jumièges , they took advantage of

6630-507: The area during this period and Rouen already had a metropolitan bishop by the 4th century. The ecclesiastical province of Rouen was based on the frame of the Roman Lugdunensis Secunda , whose limits corresponded almost exactly to the future duchy of Normandy. In 406, Germanic tribes began invading from the east, followed by dispersed settlements mainly in the Pays de Bray , Pays de Caux and Vexin . As early as 487,

SECTION 50

#1732766021146

6760-400: The assumption that each point crossed by a traveling wavefront becomes the source of a secondary wavefront. Given the initial position of a traveling wavefront, any later position (according to Huygens) was the common tangent surface ( envelope ) of the secondary wavefronts emitted from the earlier position. As the extent of the common tangent was limited by the extent of the initial wavefront,

6890-482: The beaches. Caen , Cherbourg , Carentan , Falaise and other Norman towns endured many casualties in the Battle of Normandy , which continued until the closing of the so-called Falaise gap between Chambois and Mont Ormel . The liberation of Le Havre followed. This was a significant turning point in the war in western Europe and led to the restoration of the French Republic. The remainder of Normandy

7020-570: The collection of the Philosophical Transactions . Fresnel would not have ready access to these works outside Paris, and could not read English. But, in Mathieu—with a point-source of light made by focusing sunlight with a drop of honey, a crude micrometer of his own construction, and supporting apparatus made by a local locksmith—he began his own experiments. His technique was novel: whereas earlier investigators had projected

7150-414: The colors of " thin plates " (e.g., " Newton's rings ", and the colors of skylight reflected in soap bubbles), on the assumption that light consists of periodic waves, with the lowest frequencies (longest wavelengths ) at the red end of the spectrum, and the highest frequencies (shortest wavelengths) at the violet end. In 1672 he published a heavy hint to that effect, but contemporary supporters of

7280-732: The colors of a thin plate as the combined effect of the front and back reflections, which reinforce or cancel each other according to the wavelength and the thickness. Young similarly explained the colors of "striated surfaces" (e.g., gratings ) as the wavelength-dependent reinforcement or cancellation of reflections from adjacent lines. He described this reinforcement or cancellation as interference . Neither Newton nor Huygens satisfactorily explained diffraction —the blurring and fringing of shadows where, according to rectilinear propagation, they ought to be sharp. Newton, who called diffraction "inflexion", supposed that rays of light passing close to obstacles were bent ("inflected"); but his explanation

7410-451: The conditions of Maupertuis's principle. In contrast, Young proceeded to show that "a medium more easily compressible in one direction than in any direction perpendicular to it, as if it consisted of an infinite number of parallel plates connected by a substance somewhat less elastic" admits spheroidal longitudinal wavefronts, as Huygens supposed. But Malus, in the midst of his experiments on double refraction, noticed something else: when

7540-523: The conquest of England and the subsequent invasions of Wales and Ireland, the Normans expanded into other areas. Norman families, such as that of Tancred of Hauteville , Rainulf Drengot and Guimond de Moulins played important parts in the conquest of southern Italy and the Crusades . The Drengot lineage, de Hauteville's sons William Iron Arm , Drogo , and Humphrey , Robert Guiscard and Roger

7670-613: The conquest. In 1204, during the reign of John, King of England , mainland Normandy was captured from the English by the forces of Philip II of France , ending some 293 years of relative Norman independence from the French crown. Insular Normandy (the Channel Islands) remained under control of the English, though still attached to the ecclesiastical province of Rouen. In the 1259 Treaty of Paris , Henry III of England recognized

7800-429: The departments of Mayenne and Sarthe . The Channel Islands (French: Îles Anglo-Normandes ) are also historically part of Normandy; they cover 194 square kilometres (75 sq mi) and comprise two bailiwicks : Guernsey and Jersey , which are British Crown Dependencies. Normandy's name comes from the settlement of the territory by Vikings (" Northmen ") starting in the 9th century, and confirmed by treaty in

7930-520: The designation of Professional Engineer (P. Eng.). This designation was unveiled at the CAP congress in 1999 and already more than 200 people carry this distinction. To get the certification, at minimum proof of honours bachelor or higher degree in physics or a closely related discipline must be provided. Also, the physicist must have completed, or be about to complete, three years of recent physics-related work experience after graduation. And, unless exempted,

SECTION 60

#1732766021146

8060-505: The distance between like "fits" depending on the color and the medium  and, awkwardly, on the angle of refraction or reflection into that medium. More awkwardly still, this theory required thin plates to reflect only at the back surface, although thick plates manifestly reflected also at the front surface. It was not until 1801 that Thomas Young , in the Bakerian Lecture for that year, cited Newton's hint, and accounted for

8190-459: The early 1600s. The work on mechanics , along with a mathematical treatment of physical systems, was further developed by Christiaan Huygens and culminated in Newton's laws of motion and Newton's law of universal gravitation by the end of the 17th century. The experimental discoveries of Faraday and the theory of Maxwell's equations of electromagnetism were developmental high points during

8320-524: The earth was not disturbed by the motion of the earth. The outstanding strength of Huygens's theory was his explanation of the birefringence (double refraction) of " Iceland crystal " (transparent calcite ), on the assumption that the secondary waves are spherical for the ordinary refraction (which satisfies Snell's law) and spheroidal for the extraordinary refraction (which does not). In general, Huygens's common-tangent construction implies that rays are paths of least time between successive positions of

8450-470: The end of his life, that if light consisted of waves it would "bend and spread every way" into the shadows. Huygens's theory neatly explained the law of ordinary reflection and the law of ordinary refraction ("Snell's law"), provided that the secondary waves traveled slower in denser media (those of higher refractive index ). The corpuscular theory, with the hypothesis that the corpuscles were subject to forces acting perpendicular to surfaces, explained

8580-506: The explanation and the law of colored fringes which one notices in the shadows of bodies illuminated by a luminous point." In the same paragraph, however, Fresnel implicitly acknowledged doubt about the novelty of his work: noting that he would need to incur some expense in order to improve his measurements, he wanted to know "whether this is not useless, and whether the law of diffraction has not already been established by sufficiently exact experiments."  He explained that he had not yet had

8710-525: The extraordinary refraction, which rode on his authority through the 18th century, although he made "no known attempt to deduce it from any principles of optics, corpuscular or otherwise."  In 1808, the extraordinary refraction of calcite was investigated experimentally, with unprecedented accuracy, by Étienne-Louis Malus , and found to be consistent with Huygens's spheroid construction, not Newton's "Rule". Malus, encouraged by Pierre-Simon Laplace , then sought to explain this law in corpuscular terms: from

8840-427: The first publication of his pure-transverse-wave hypothesis, and the submission of his first correct solution to the biaxial problem, was less than a year. Later, he coined the terms linear polarization , circular polarization , and elliptical polarization , explained how optical rotation could be understood as a difference in propagation speeds for the two directions of circular polarization, and (by allowing

8970-421: The first satisfactory explanation of diffraction by straight edges, including the first satisfactory wave-based explanation of rectilinear propagation. Part of his argument was a proof that the addition of sinusoidal functions of the same frequency but different phases is analogous to the addition of forces with different directions. By further supposing that light waves are purely transverse , Fresnel explained

9100-480: The former province. On 13 July 1793, the Norman Charlotte Corday assassinated Jean-Paul Marat . The Normans reacted little to the many political upheavals which characterized the 19th century. Overall, they warily accepted the changes of régime ( First French Empire , Bourbon Restoration , July Monarchy , French Second Republic , Second French Empire , French Third Republic ). Following

9230-568: The fringes onto a screen, Fresnel soon abandoned the screen and observed the fringes in space, through a lens with the micrometer at its focus, allowing more accurate measurements while requiring less light. Later in July, after Napoleon's final defeat, Fresnel was reinstated with the advantage of having backed the winning side. He requested a two-month leave of absence, which was readily granted because roadworks were in abeyance. On 23 September he wrote to Arago, beginning "I think I have found

9360-443: The fringes were hyperbolic. In the part of the memoir that most clearly surpassed Young, Fresnel explained the ordinary laws of reflection and refraction in terms of interference, noting that if two parallel rays were reflected or refracted at other than the prescribed angle, they would no longer have the same phase in a common perpendicular plane, and every vibration would be cancelled by a nearby vibration. He noted that his explanation

9490-708: The increasing expectations and requirements for which any profession must take responsibility". Chartered Physicist is considered to be equal in status to Chartered Engineer, which the IoP also awards as a member of the Engineering Council UK, and other chartered statuses in the UK. It is also considered a "regulated profession" under the European professional qualification directives. The Canadian Association of Physicists can appoint an official designation called Professional Physicist ( P. Phys. ), similar to

9620-416: The internal fringes by considering the intersections of circular wavefronts emitted from the two edges of the obstruction, and the external fringes by considering the intersections between direct waves and waves reflected off the nearer edge. For the external fringes, to obtain tolerable agreement with observation, he had to suppose that the reflected wave was inverted ; and he noted that the predicted paths of

9750-399: The known relation between the incident and refracted ray directions, Malus derived the corpuscular velocity (as a function of direction) that would satisfy Maupertuis 's "least action" principle. But, as Young pointed out, the existence of such a velocity law was guaranteed by Huygens's spheroid, because Huygens's construction leads to Fermat's principle, which becomes Maupertuis's principle if

9880-519: The landscape is created by the meanders of the Seine as it approaches its estuary. The highest point is the Signal d'Écouves (417 m), in the Armorican Massif. Normandy is sparsely forested: 12.8% of the territory is wooded, compared to a French average of 23.6%, although the proportion varies between the departments. Eure has the most cover, at 21%, while Manche has the least, at 4%,

10010-1180: The largest employer being the last. Physicists in academia or government labs tend to have titles such as Assistants, Professors , Sr./Jr. Scientist, or postdocs . As per the American Institute of Physics , some 20% of new physics Ph.D.s holds jobs in engineering development programs, while 14% turn to computer software and about 11% are in business/education. A majority of physicists employed apply their skills and training to interdisciplinary sectors (e.g. finance ). Job titles for graduate physicists include Agricultural Scientist , Air Traffic Controller , Biophysicist , Computer Programmer , Electrical Engineer , Environmental Analyst , Geophysicist , Medical Physicist , Meteorologist , Oceanographer , Physics Teacher / Professor / Researcher , Research Scientist , Reactor Physicist , Engineering Physicist , Satellite Missions Analyst, Science Writer , Stratigrapher , Software Engineer , Systems Engineer , Microelectronics Engineer , Radar Developer, Technical Consultant, etc. The majority of Physics terminal bachelor's degree holders are employed in

10140-590: The late 3rd century AD, Germanic raids devastated "Lugdunensis Secunda", as the modern area of Normandy was known at the time. The Romans built a system of coastal defences known as Saxon Shore on both sides of the English Channel. Coastal settlements were raided by Saxon pirates that finally settled mainly in the Bessin region. Modern archeology reveals their presence in different Merovingian cemeteries excavated east of Caen. Christianity also began to enter

10270-571: The lead, controversially, to Biot. Such were the circumstances in which Arago first heard of Fresnel's interest in optics. Fresnel's letters from later in 1814 reveal his interest in the wave theory, including his awareness that it explained the constancy of the speed of light and was at least compatible with stellar aberration. Eventually he compiled what he called his rêveries (musings) into an essay and submitted it via Léonor Mérimée to André-Marie Ampère , who did not respond directly. But on 19 December, Mérimée dined with Ampère and Arago, with whom he

10400-459: The legitimacy of the French possession of mainland Normandy. His successors, however, often fought to regain control of their ancient fiefdom. The Charte aux Normands granted by Louis X of France in 1315 (and later re-confirmed in 1339) – like the analogous Magna Carta granted in England in the aftermath of 1204 – guaranteed the liberties and privileges of the province of Normandy. Normandy

10530-437: The light from one side was blocked, and concluded that "the vibrations of two rays that cross each other under a very small angle can contradict each other…"  But, whereas Young took the disappearance of the internal fringes as confirmation of the principle of interference, Fresnel reported that it was the internal fringes that first drew his attention to the principle. To explain the diffraction pattern, Fresnel constructed

10660-535: The metropolitan area) and formerly the capital of Lower Normandy; Le Havre (296,773 in the metropolitan area); and Cherbourg (117,855 in the metropolitan area). The traditional provincial flag of Normandy , gules, two leopards passant or , is used in the region and its predecessors. The three-leopard version (known in the Norman language as les treis cats , "the three cats") is used by some associations and individuals, especially those who support cultural links with

10790-636: The middle of the year. Meanwhile, in an experiment reported on 26 February 1816, Arago verified Fresnel's prediction that the internal fringes were shifted if the rays on one side of the obstacle passed through a thin glass lamina. Fresnel correctly attributed this phenomenon to the lower wave velocity in the glass. Arago later used a similar argument to explain the colors in the scintillation of stars. Physicist Physicists can apply their knowledge towards solving practical problems or to developing new technologies (also known as applied physics or engineering physics ). The study and practice of physics

10920-483: The nature of polarization , the mechanism of chromatic polarization, and the transmission and reflection coefficients at the interface between two transparent isotropic media. Then, by generalizing the direction-speed-polarization relation for calcite , he accounted for the directions and polarizations of the refracted rays in doubly-refractive crystals of the biaxial class (those for which Huygens's secondary wavefronts are not axisymmetric ). The period between

11050-407: The ordinary ray emerging from the first crystal suffers only the ordinary refraction in the second, while the extraordinary ray emerging from the first suffers only the extraordinary refraction in the second; but when the second crystal is rotated 90° about the incident rays, the roles are interchanged, so that the ordinary ray emerging from the first crystal suffers only the extraordinary refraction in

11180-608: The past 30 years. In the Late Roman Empire a new province was created and called Lugdunensis Secunda , it sketched the later ecclesiastical province of Rouen , with the Metropolis civitas Rotomagensium ( Rouen ), Civitas Baiocassium ( Augustodorum , Bayeux), Civitas Abrincatum ( Ingena , Avranches), Civitas Ebroicorum ( Mediolanum , Évreux), Civitas Saiorum (Sées), Civitas Lexoviorum ( Noviomagus , Lisieux / Lieuvin) and Civitas Constantia (Coutances). In

11310-536: The period between Fresnel's unification of physical optics and Maxwell's wider unification, a contemporary authority, Humphrey Lloyd , described Fresnel's transverse-wave theory as "the noblest fabric which has ever adorned the domain of physical science, Newton's system of the universe alone excepted."  Augustin-Jean Fresnel (also called Augustin Jean or simply Augustin), born in Broglie, Normandy , on 10 May 1788,

11440-418: The periodicity of the color as a function of the plate thickness—including the factor by which the period exceeded that for a reflective thin plate, and even the effect of obliquity of the plate (but not the role of polarization)—could be explained by the wave theory in terms of the different propagation times of the ordinary and extraordinary waves through the plate. But Young was then the only public defender of

11570-466: The polarization of light. I saw in the Moniteur of a few months ago that Biot had read to the Institute a very interesting memoir on the polarization of light . Though I break my head, I cannot guess what that is. As late as 28 December he was still waiting for information, but by 10 February 1815 he had received Biot's memoir. (The Institut de France had taken over the functions of

11700-413: The polarizers work by reflection or double refraction, and that all birefringent crystals produce both extraordinary refraction and polarization. As the corpuscularists started trying to explain these things in terms of polar "molecules" of light, the wave-theorists had no working hypothesis on the nature of polarization, prompting Young to remark that Malus's observations "present greater difficulties to

11830-493: The popular story that he hardly began to read until the age of eight is disputed. At the age of nine or ten he was undistinguished except for his ability to turn tree-branches into toy bows and guns that worked far too well, earning himself the title l'homme de génie (the man of genius) from his accomplices, and a united crackdown from their elders. In 1801, Augustin was sent to the École Centrale at Caen , as company for Louis. But Augustin lifted his performance: in late 1804 he

11960-656: The power vacuum created by the disintegration of Charlemagne 's empire to take Northern France. The fiefdom of Normandy was created for the Viking leader Hrólfr , known in Medieval Latin as Rollo . Rollo had besieged Paris but in 911 entered vassalage to the king of the West Franks , Charles the Simple , through the Treaty of Saint-Clair-sur-Epte . In exchange for his homage and fealty , Rollo legally gained

12090-433: The private sector. Other fields are academia, government and military service, nonprofit entities, labs and teaching. Typical duties of physicists with master's and doctoral degrees working in their domain involve research, observation and analysis, data preparation, instrumentation, design and development of industrial or medical equipment, computing and software development, etc. The highest honor awarded to physicists

12220-399: The ray speed is replaced by the reciprocal of the particle speed! The corpuscularists had not found a force law that would yield the alleged velocity law, except by a circular argument in which a force acting at the surface of the crystal inexplicably depended on the direction of the (possibly subsequent) velocity within the crystal. Worse, it was doubtful that any such force would satisfy

12350-470: The reflection coefficient to be complex ) accounted for the change in polarization due to total internal reflection , as exploited in the Fresnel rhomb . Defenders of the established corpuscular theory could not match his quantitative explanations of so many phenomena on so few assumptions. Fresnel had a lifelong battle with tuberculosis , to which he succumbed at the age of 39. Although he did not become

12480-415: The repeated application of Huygens's construction to a plane wavefront of limited extent (in a uniform medium) gave a straight, parallel beam. While this construction indeed predicted rectilinear propagation, it was difficult to reconcile with the common observation that wavefronts on the surface of water can bend around obstructions, and with the similar behavior of sound waves—causing Newton to maintain, to

12610-406: The same color as the background). The light emerging from the mica was " de polarized" in the sense that there was no orientation of the calcite that made one image disappear; yet it was not ordinary (" un polarized") light, for which the two images would be of the same color. Rotating the calcite around the line of sight changed the colors, though they remained complementary. Rotating the mica changed

12740-422: The same discoveries but had not had time to write them up. In fact the overlap between Arago's work and Biot's was minimal, Arago's being only qualitative and wider in scope (attempting to include polarization by reflection). But the dispute triggered a notorious falling-out between the two men. Later that year, Biot tried to explain the observations as an oscillation of the alignment of the "affected" corpuscles at

12870-459: The same ground using a gypsum lamina in place of the mica, and found empirical formulae for the intensities of the ordinary and extraordinary images. The formulae contained two coefficients, supposedly representing colors of rays "affected" and "unaffected" by the plate—the "affected" rays being of the same color mix as those reflected by amorphous thin plates of proportional, but lesser, thickness. Arago protested, declaring that he had made some of

13000-400: The same laws equally well, albeit with the implication that light traveled faster in denser media; that implication was wrong, but could not be directly disproven with the technology of Newton's time or even Fresnel's time (see Foucault's measurements of the speed of light ) . Similarly inconclusive was stellar aberration —that is, the apparent change in the position of a star due to

13130-405: The second, and vice versa. This discovery gave Newton another reason to reject the wave theory: rays of light evidently had "sides". Corpuscles could have sides  (or poles , as they would later be called); but waves of light could not, because (so it seemed) any such waves would need to be longitudinal (with vibrations in the direction of propagation). Newton offered an alternative "Rule" for

13260-545: The sick list. Returning to Nyons in defeat, he was threatened and had his windows broken. During the Hundred Days he was placed on suspension, which he was eventually allowed to spend at his mother's house in Mathieu. There he used his enforced leisure to begin his optical experiments. The appreciation of Fresnel's reconstruction of physical optics might be assisted by an overview of the fragmented state in which he found

13390-414: The southern département of Drôme , to assist with the imperial highway that was to connect Spain and Italy. It is from Nyons that we have the first evidence of his interest in optics. On 15 May 1814, while work was slack due to Napoleon 's defeat, Fresnel wrote a " P.S. " to his brother Léonor, saying in part: I would also like to have papers that might tell me about the discoveries of French physicists on

13520-518: The subject. In this subsection, optical phenomena that were unexplained or whose explanations were disputed are named in bold type . The corpuscular theory of light , favored by Isaac Newton and accepted by nearly all of Fresnel's seniors, easily explained rectilinear propagation : the corpuscles obviously moved very fast, so that their paths were very nearly straight. The wave theory , as developed by Christiaan Huygens in his Treatise on Light (1690), explained rectilinear propagation on

13650-444: The surrender of French possessions in 1801, and the belief that the rights of succession to that title are subject to Salic Law which excludes inheritance through female heirs. Rivers in Normandy include: And many coastal rivers: The modern region of Normandy was created by the territorial reform of French Regions in 2014 by the merger of Lower Normandy , and Upper Normandy . The new region took effect on 1 January 2016, after

13780-444: The term plane of polarization . In the case of polarization by reflection, his "plane of polarization" was the plane of the incident and reflected rays; in modern terms, this is the plane normal to the electric vibration. In 1809, Malus further discovered that the intensity of light passing through two polarizers is proportional to the squared cosine of the angle between their planes of polarization ( Malus's law ), whether

13910-471: The territory that he and his Viking allies had previously conquered. The name "Normandy" reflects Rollo's Viking (" Norseman ") origins. The descendants of Rollo and his followers created an aristocracy that step by step adopted the local Gallo-Romance language , intermarried with the area's native Gallo-Frankish inhabitants, and adopted Christianity. Nevertheless, the first generations of Scandinavian and Anglo-Scandinavian settlers brought slaves, mainly from

14040-660: The title Duke of Normandy in respect to the Channel Islands. The Channel Islands (except for Chausey ) remain Crown Dependencies of the British Crown in the present era. Thus the Loyal Toast in the Channel Islands is Le Roi, notre Duc ("The King, our Duke"). The British monarch is understood to not be the Duke with regards to mainland Normandy described herein, by virtue of the Treaty of Paris of 1259 ,

14170-520: The use of "stepped" lenses to extend the visibility of lighthouses , saving countless lives at sea. The simpler dioptric (purely refractive) stepped lens, first proposed by Count Buffon   and independently reinvented by Fresnel, is used in screen magnifiers and in condenser lenses for overhead projectors . By expressing Huygens 's principle of secondary waves and Young 's principle of interference in quantitative terms, and supposing that simple colors consist of sinusoidal waves, Fresnel gave

14300-440: The velocity of the earth across the line of sight (not to be confused with stellar parallax , which is due to the displacement of the earth across the line of sight). Identified by James Bradley in 1728, stellar aberration was widely taken as confirmation of the corpuscular theory. But it was equally compatible with the wave theory, as Euler noted in 1746—tacitly assuming that the aether (the supposed wave-bearing medium) near

14430-411: The wave theory could not yet link it to polarization. The corpuscular theory was weak on thin plates and silent on gratings; the wave theory was strong on both, but under-appreciated. Concerning diffraction, the corpuscular theory did not yield quantitative predictions, while the wave theory had begun to do so by considering diffraction as a manifestation of interference, but had only considered two rays at

14560-486: The wave theory failed to act on it: Robert Hooke treated light as a periodic sequence of pulses but did not use frequency as the criterion of color, while Huygens treated the waves as individual pulses without any periodicity; and Pardies died young in 1673. Newton himself tried to explain colors of thin plates using the corpuscular theory, by supposing that his corpuscles had the wavelike property of alternating between "fits of easy transmission" and "fits of easy reflection",

14690-443: The wave theory. In summary, in the spring of 1814, as Fresnel tried in vain to guess what polarization was, the corpuscularists thought that they knew, while the wave-theorists (if we may use the plural) literally had no idea. Both theories claimed to explain rectilinear propagation, but the wave explanation was overwhelmingly regarded as unconvincing. The corpuscular theory could not rigorously link double refraction to surface forces;

14820-462: The wavefront, in accordance with Fermat's principle . In the special case of isotropic media, the secondary wavefronts must be spherical, and Huygens's construction then implies that the rays are perpendicular to the wavefront; indeed, the law of ordinary refraction can be separately derived from that premise, as Ignace-Gaston Pardies did before Huygens. Although Newton rejected the wave theory, he noticed its potential to explain colors, including

14950-400: Was about to leave Paris, Arago left him a note on a new topic: I do not know of any book that contains all the experiments that physicists are doing on the diffraction of light. M'sieur Fresnel will only be able to get to know this part of the optics by reading the work by Grimaldi , the one by Newton, the English treatise by Jordan, and the memoirs of Brougham and Young, which are part of

15080-455: Was accepted into the École Polytechnique, being placed 17th in the entrance examination. As the detailed records of the École Polytechnique begin in 1808, we know little of Augustin's time there, except that he made few if any friends and—in spite of continuing poor health—excelled in drawing and geometry: in his first year he took a prize for his solution to a geometry problem posed by Adrien-Marie Legendre . Graduating in 1806, he then enrolled at

15210-467: Was acquainted through the École Polytechnique; and Arago promised to look at Fresnel's essay. In mid 1815, on his way home to Mathieu to serve his suspension, Fresnel met Arago in Paris and spoke of the wave theory and stellar aberration. He was informed that he was trying to break down open doors (" il enfonçait des portes ouvertes "), and directed to classical works on optics. On 12 July 1815, as Fresnel

15340-523: Was assigned to Rennes in the département of Ille-et-Vilaine . At this point Arago interceded with Gaspard de Prony , head of the École des Ponts, who wrote to Louis-Mathieu Molé , head of the Corps des Ponts, suggesting that the progress of science and the prestige of the Corps would be enhanced if Fresnel could come to Paris for a time. He arrived in March 1816, and his leave was subsequently extended through

15470-458: Was becoming expensive on assumptions. But in 1813, Biot reported that the case of quartz was simpler: the observable phenomenon (now called optical rotation or optical activity or sometimes rotary polarization ) was a gradual rotation of the polarization direction with distance, and could be explained by a corresponding rotation ( not oscillation) of the corpuscles. Early in 1814, reviewing Biot's work on chromatic polarization, Young noted that

15600-401: Was caused by interference between two rays: one reflected off the edge, and the other inflected while passing near the edge. The latter ray would be undeviated if sufficiently far from the edge, but Young did not elaborate on that case. These were the earliest suggestions that the degree of diffraction depends on wavelength. Later, in the 1803 Bakerian Lecture, Young ceased to regard inflection as

15730-746: Was coined by William Whewell (also the originator of the term "scientist") in his 1840 book The Philosophy of the Inductive Sciences . A standard undergraduate physics curriculum consists of classical mechanics , electricity and magnetism , non-relativistic quantum mechanics , optics , statistical mechanics and thermodynamics , and laboratory experience. Physics students also need training in mathematics ( calculus , differential equations , linear algebra , complex analysis , etc.), and in computer science . Any physics-oriented career position requires at least an undergraduate degree in physics or applied physics, while career options widen with

15860-538: Was devastated by various civil wars and the Hundred Years' War . Between 1419 and 1450, the English controlled all of Normandy apart from Mont-Saint-Michel , and made Rouen the seat of their power in France. Normandy ultimately saw its population decline by three quarters as a result of the various conflicts which took place in the region during the late Middle Ages. Afterwards, prosperity returned to Normandy until

15990-438: Was estimated at 3,260,000 with an average population density of 109 inhabitants per km , just under the French national average, but rising to 147 for Upper Normandy . The population of the Channel Islands is estimated around 174,000 (2021). The main cities (population given from the 1999 census) are Rouen (518,316 in the metropolitan area), the capital since 2016 of the province and formerly of Upper Normandy; Caen (420,000 in

16120-460: Was initially posted to the western département of Vendée . There, in 1811, he anticipated what became known as the Solvay process for producing soda ash , except that recycling of the ammonia was not considered. That difference may explain why leading chemists, who learned of his discovery through his uncle Léonor, eventually thought it uneconomic. About 1812, Fresnel was sent to Nyons , in

16250-466: Was liberated by Allied forces only on 9 May 1945 at the end of the war, when the Channel Island occupation effectively ended. Despite the renunciation of the Duke of Normandy title by Henry III of England in the 1259 Treaty of Paris , and the extinction of the duchy itself in modern-day, republican France, in the Channel Islands the monarch of the United Kingdom (whether a king or queen)

16380-511: Was not a member of the institute, the fate of his memoir depended heavily on the report of a single member. The reporter for Fresnel's memoir turned out to be Arago (with Poinsot as the other reviewer). On 8 November, Arago wrote to Fresnel: I have been instructed by the Institute to examine your memoir on the diffraction of light; I have studied it carefully, and found many interesting experiments, some of which had already been done by Dr. Thomas Young, who in general regards this phenomenon in

16510-412: Was only qualitative. Huygens's common-tangent construction, without modifications, could not accommodate diffraction at all. Two such modifications were proposed by Young in the same 1801 Bakerian Lecture: first, that the secondary waves near the edge of an obstacle could diverge into the shadow, but only weakly, due to limited reinforcement from other secondary waves; and second, that diffraction by an edge

16640-522: Was the second of four sons of the architect Jacques Fresnel and his wife Augustine, née Mérimée. The family moved twice—in 1789/90 to Cherbourg , and in 1794  to Jacques's home town of Mathieu , where Augustine would spend 25 years as a widow, outliving two of her sons. The first son, Louis, was admitted to the École Polytechnique , became a lieutenant in the artillery, and was killed in action at Jaca , Spain. The third, Léonor, followed Augustin into civil engineering , succeeded him as secretary of

16770-417: Was troubled, wanting to know more precisely where he had collided with Young. Concerning the curved paths of the "colored bands", Young had noted the hyperbolic paths of the fringes in the two-source interference pattern, corresponding roughly to Fresnel's internal fringes, and had described the hyperbolic fringes that appear on the screen within rectangular shadows. He had not mentioned the curved paths of

16900-420: Was valid provided that the surface irregularities were much smaller than the wavelength. On 10 November, Fresnel sent a supplementary note dealing with Newton's rings and with gratings, including, for the first time, transmission gratings—although in that case the interfering rays were still assumed to be "inflected", and the experimental verification was inadequate because it used only two threads. As Fresnel

#145854