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activité expérience de michelson et morley

2 Combining this value for α with the Kennedy–Thorndike null result shows that β must assume the value of relativistic length contraction. λ The results of such experiments were all negative. 3 Displacements of 1/1000 of a fringe could be measured on the photographic plates. φ These include experiments from 1902 to 1905, and a series of experiments in the 1920s. − {\textstyle T_{3}=L/{\sqrt {c^{2}-v^{2}}}} c <> To avoid the possibility of the aether wind being blocked by solid walls, his mountaintop observations used a special shed with thin walls, mainly of canvas. [A 17]. Lacking modern means of environmental temperature control, experimentalists struggled with continual fringe drift even when the interferometer was set up in a basement. 1 L' expérience de Michelson et Morley est une expérience d' optique qui a tenté de démontrer l'existence de l' éther luminifère. 3 = If 1 L 0, 1, 2 ...), there will be destructive interference and a weak signal at the detector. Hammar directed one leg of his interferometer through a heavy metal pipe plugged with lead. Next, the experiment was tried at night. because he overlooked the increased path length in the rest frame of the aether. L'expérience menée par Michelson et Morley avait pour but de montrer l'existence de l'éther luminifère. En 1881, Albert Michelson entreprena, en collaboration avec Edward Morley, une expØrience, rØelle celle-ci, pour dØterminer l’effet de ce vent d’Øther sur la vitesse de la lumiŁre. ), During the early 21st century, there has been a resurgence in interest in performing precise Michelson–Morley type experiments using lasers, masers, cryogenic optical resonators, etc. in the x direction. In 1886, Michelson and Morley successfully confirmed Fresnel's drag coefficient – this result was also considered as a confirmation of the stationary aether concept. [15][16], Miller worked on increasingly larger interferometers, culminating in one with a 32-meter (105 ft) (effective) arm length that he tried at various sites, including on top of a mountain at the Mount Wilson Observatory. This result could have been expected because during each full rotation, each arm would be parallel to the wind twice (facing into and away from the wind giving identical readings) and perpendicular to the wind twice. . Kennedy also carried out an experiment at Mount Wilson, finding only about 1/10 the drift measured by Miller and no seasonal effects. L’étude de ces textes en … Si je marche 8d. along the line of motion (originally thought to be relative to the aether), L’expérience de Michelson et Morley (entre 1881 et 1887) montre que la loi de composition des vitesses de la mécanique classique ne s’applique pas aux ondes lumineuses : la vitesse de propagation (ou célérité) c de la lumière est indépendante de la vitesse de déplacement de la Terre par rapport au Soleil (voir activité 1 page 210). {\textstyle c} 2 Edward W. Morley and Dayton C. Miller", "Report of an experiment to detect the Fitzgerald–Lorentz Effect", "A Refinement of the Michelson–Morley Experiment", "A Repetition of the Michelson–Morley Experiment Using Kennedy's Refinement", "Ether-Drift Experiments at Mount Wilson", "Über das Verhalten des Lichtes außerirdischer Lichtquellen", "L'expérience de Michelson, réalisée en ballon libre", "Nouveaux résultats obtenus par l'expérience de Michelson", "Tests of Lorentz Invariance using a Microwave Resonator", "Improved test of Lorentz invariance in electrodynamics", "Direct terrestrial test of Lorentz symmetry in electrodynamics to 10, "Postulate versus Observation in the Special Theory of Relativity", A History of the Theories of Aether and Electricity, "The Optics and Electrodynamics of Moving Bodies", "On a Possible Mode of Detecting a Motion of the Solar System through the Luminiferous Ether", "Electromagnetic phenomena in a system moving with any velocity smaller than that of light", "On the Electrodynamics of Moving Bodies", "Einstein's Investigations of Galilean Covariant Electrodynamics prior to 1905". / [A 5], According to the stationary and the partially dragged aether hypotheses, Earth and the aether are in relative motion, implying that a so-called "aether wind" (Fig. c λ To prove the existence of the aether, Michaelson and Morley sought to find the "fringe shift". L / [A 13] Instead of providing insight into the properties of the aether, Michelson and Morley's article in the American Journal of Science reported the measurement to be as small as one-fortieth of the expected displacement (Fig. 2) should exist. ) {\textstyle T_{3}} 1 {\textstyle T_{3}} 2 Le postulat de l’invariance de la vitesse de la lumière I.1. {\textstyle c} The frequencies of a pair of rotating, orthogonal microwave resonators are compared. 3/12/09 J. Surdej (2009-2010) 3 Jump to first page 3/12/2009 Newton Huygens Michelson et Morley A la recherchede la vitesseréellede la Terre dansl’espace: 2. Path difference is denoted by Δλ because the beams are out of phase by a some number of wavelengths (λ). 1 = . L’objectif de cette expérience était de montrer l’existence de l’éther dans lequel devait se propager la lumière. Il ont alors cherché à mettre en évidence la différence de vitesse de la lumière entre deux directionsperpendiculaires et à deux périodes espacées de 6 mois. 1 {\textstyle T_{1}} Michelson et Morley (probablement la plupart du temps Michelson) est venu avec l’idée que vous devriez être en mesure de mesurer le mouvement de la Terre à travers l’éther. De son expérience Michelson n'a pas conclut que la lumière était une 1 The expectation was that the effect would be graphable as a sine wave with two peaks and two troughs per rotation of the device. By analyzing the return speed of light in different directions at various different times, it was thought to be possible to measure the motion of the Earth relative to the aether. {\textstyle \varphi =1} On the other hand, the much more precise Michelson–Morley experiment (1887) apparently confirmed complete aether dragging and refuted the stationary aether. Definitive measurement of the aether wind would require an experiment with greater accuracy and better controls than the original. {\displaystyle \Delta {\lambda }_{1}=2L\left({\frac {1}{1-{\frac {v^{2}}{c^{2}}}}}-{\frac {1}{\sqrt {1-{\frac {v^{2}}{c^{2}}}}}}\right)}. a) Mode de propagation Illustration de l'expérience de Michelson-Morley On construit l'appareil de telle sorte que les miroirs M1 et M2 soient à égale distance, D, de la lame séparatrice. Cette animation présente l’expérience de Michelson et Morley de 1887. c {\textstyle vT_{1}} / If length contraction of The Michelson–Morley experiment was an attempt to detect the existence of the luminiferous aether, a supposed medium permeating space that was thought to be the carrier of light waves. Leur idØe : mesurer cette vitesse suivant 2 directions, le sens de dØplacement de la Terre sur … ℓ Examples of other experiments not based on the Michelson–Morley principle, i.e., non-optical isotropy tests achieving an even higher level of precision, are Clock comparison or Hughes–Drever experiments. . Le but de l'expérience de Michelson et Morley était de déterminer si la terre se déplaçait dans l'éther. T 1 φ Therefore, the Lorentz transformation with and expérience de Michelson et Morley, f 1 "[A 2]:219, Michelson–Morley type experiments have been repeated many times with steadily increasing sensitivity. is true (if the velocity of the aether is small relative to the speed of light), then the expression can be simplified using a first order binomial expansion; ( Because the speed of light is so great, and because material bodies pass through the aether without obvious friction or drag, it was assumed to have a highly unusual combination of properties. = Nous noterons v la vitesse de la Terre sur son orbite et L la longueur de chacun des bras de l'interféromètre. L’éther est généralement considéré comme statique et immobile (sauf, bien sûr, pour la vibration), mais la Terre se déplaçait rapidement. After leaving the splitter, the beams traveled out to the ends of long arms where they were reflected back into the middle by small mirrors. is an unavoidable consequence of the combination of these three experiments. Albert Einstein a toujours prétendu + [A 28] However de Sitter noted that emitter theory predicted several optical effects that were not seen in observations of binary stars in which the light from the two stars could be measured in a spectrometer. 3 The Earth is in motion, so two main possibilities were considered: (1) The aether is stationary and only partially dragged by Earth (proposed by Augustin-Jean Fresnel in 1818), or (2) the aether is completely dragged by Earth and thus shares its motion at Earth's surface (proposed by Sir George Stokes, 1st Baronet in 1844). T [A 5] In addition, James Clerk Maxwell (1865) recognized the electromagnetic nature of light and developed what are now called Maxwell's equations, but these equations were still interpreted as describing the motion of waves through an aether, whose state of motion was unknown. = . This derivation is true if the experiment is orientated by any factor of 90° with respect to the aether wind. Michelson suffered a nervous breakdown in September 1885, from which he recovered by October 1885. [A 5][A 4]. c ) If the path difference is a full number of wavelengths plus one half, deconstructive interference is observed (central fringe will be black). {\textstyle cT_{2}=L-vT_{2}} Introduction I.2. x v − 2 reversed, resulting in 3 To find the fringe shift, subtract the path difference in first orientation by the path difference in the second, then divide by the wavelength, λ, of light[10]; Note the difference between Δλ, which is some number of wavelengths, and λ which is a single wavelength. . 8) converted the task of detecting fringe shifts from the relatively insensitive one of estimating their lateral displacements to the considerably more sensitive task of adjusting the light intensity on both sides of a sharp boundary for equal luminance. {\textstyle L/\gamma } The theory postulates that light has always the same velocity in respect to the source. For instance, if [A 29][A 30] Morley was not convinced of his own results, and went on to conduct additional experiments with Dayton Miller from 1902 to 1904. v The number of weights added or removed provided a measure of the fringe shift. {\displaystyle c{\Delta }T=\Delta \lambda } 2 L 2 First, the Michelson–Morley experiment showed that the speed of light is independent of the orientation of the apparatus, establishing the relationship between longitudinal (β) and transverse (δ) lengths. However, since the nuclear wave functions for different MJ have different orientations in space relative to the magnetic field, any orientation dependence, whether from an aether wind or from a dependence on the large-scale distribution of mass in space (see Mach's principle), would perturb the energy spacings between the four levels, resulting in an anomalous broadening or splitting of the line. If one uses a half-silvered mirror as the beam splitter, the reflected beam will undergo a different number of front-surface reflections than the transmitted beam. After the "failed" experiment Michelson and Morley ceased their aether drift measurements and started to use their newly developed technique to establish the wavelength of light as a standard of length.[6][7]. v L / φ Je fais un TPE sur l'histoire de la relativité restreinte et j'aborde donc l'expérience de Michelson et Morley. The result was negative, in that Michelson and Morley found no significant difference between the speed of light in the direction of movement through the presumed aether, and the speed at right angles. %���� Thus 1 The negative result led Michelson to the conclusion that there is no measurable aether drift[1]. 2 J'ai lu la description de l'ex After reanalyzing Miller's original data using modern techniques of quantitative error analysis, Roberts found Miller's apparent signals to be statistically insignificant. [6][7] At this time Michelson was professor of physics at the Case School of Applied Science, and Morley was professor of chemistry at Western Reserve University (WRU), which shared a campus with the Case School on the eastern edge of Cleveland. Théorie ondulatoire de la Δ 2 A number of physicists therefore attempted to make measurements of indirect first-order effects not of the speed of light itself, but of variations in the speed of light (see First order aether-drift experiments). 2 Michelson et Morley […] de sorte qu’il est perm is de dire qu’à l’heure actuelle, nous ne saurions nous imaginer l’Ether qui nous entoure, ni comme étant en repos, ni comme suivant la terre dans son mouvement, ou plutôt que nous sommes obligés de faire alternativement − This hypothesis was partly motivated by Oliver Heaviside's discovery in 1888 that electrostatic fields are contracting in the line of motion. endobj v Because of the motion of the Earth around the Sun, the measured data were also expected to show annual variations. Michelson (1881) wrote: "... owing to the extreme sensitiveness of the instrument to vibrations, the work could not be carried on during the day. The classical analysis predicted a relative phase shift between the longitudinal and transverse beams which in Michelson and Morley's apparatus should have been readily measurable. ( . For instance, the Fizeau–Foucault apparatus could measure the speed of light to perhaps 5% accuracy, which was quite inadequate for measuring directly a first-order 0.01% change in the speed of light. 2 γ Le but de l’expérience de Michelson et de Morley était de mettre en évidence le mouvement de la Terre par rapport à l’éther qui était alors considéré comme un référentiel absolu. Joao Magueijo, PLUS VITE QUE LA LUMIERE, Dunod, 2003, p.33: "Ils [Michelson et Morley] établirent empiriquement que la vitesse de la lumière était toujours identique, quel que soit le mouvement de l'obsevateur. If the Earth is traveling through an aether medium, a light beam traveling parallel to the flow of that aether will take longer to reflect back and forth than would a beam traveling perpendicular to the aether, because the increase in elapsed time from traveling against the aether wind is more than the time saved by traveling with the aether wind. c Thirring (1926) as well as Lorentz pointed out that Miller's results failed even the most basic criteria required to believe in their celestial origin, namely that the azimuth of supposed drift should exhibit daily variations consistent with the source rotating about the celestial pole. c 2 So far, no one has been able to replicate Miller's results, and modern experimental accuracies have ruled them out. λ L Walther Ritz's emission theory (or ballistic theory) was also consistent with the results of the experiment, not requiring aether. / 2 0 obj c 3 0 obj They set a limit on the anisotropy of the speed of light resulting from the Earth's motions of Δc/c ≈ 10−15, where Δc is the difference between the speed of light in the x- and y-directions.[34]. v is the moving longitudinal length and Comparison with the discussion in Section 11 shows that also from the standpoint of the theory of relativity this solution of the difficulty was the right one. (c) Expliquer pourquoi le concept d’ « éther » n'est ainsi plus pertinent selon Einstein. "[1] Although this small "velocity" was measured, it was considered far too small to be used as evidence of speed relative to the aether, and it was understood to be within the range of an experimental error that would allow the speed to actually be zero. If emission theory were correct, the light from the stars should experience unusual fringe shifting due to the velocity of the stars being added to the speed of the light, but no such effect could be seen. Thus , which was shown by Lorentz (1904) to be unity. L Other experimenters from around the world increased accuracy, eliminated possible side effects, or both. against a river flowing with velocity ( Michelson-Morley Experiment This movie simulates the set-up used in the Michelson-Morley experiment, including the non-existent aether wind they were trying to detect! ) L'expérience a été développée par Michelson et Morley dans le but de mesurer la vitesse de la lumière dans son support supposé, l'éther à l'époque, en se basant sur la loi d'addition des vitesses. T Because the two beams undergo a different number of phase inversions, when the path lengths of the two beams match or differ by an integral number of wavelengths (e.g. c v Bonjour. When the mirrors were moved out to the ends of the arms, the fringes were only occasionally visible. (

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