In Young's Double Slit Experiment (YDE) and improved versions, waves causing interference travel different distances.As speed of light is constant, waves require different time spans to reach the point of interference.Thereby, if the waves are generated simultaneously at the slits/source, they cannot meet on the screen anywhere outside the mid-line.Formation of fringes is commonly interpreted as interference caused by the meeting (super-positioning) of two waves generated simultaneously.The reality is that fringes are formed by interference of waves generated at different times.However, unless impacted by other phenomena, two waves generated at different times converging to form fringes, as this paper shows, will mandatorily come in same phase to the interference point, producing constructive interference.Interference observed, however, is not only constructive.The effect on the phase of waves while bending (diffraction) is also to be considered.Consequently, it addresses three phenomena causing phase shifts: (1)different starting times,(2)bending at slits, and (3)distances traveled (In contrast, the first two are overlooked by the conventional approach).(Dirac and Feynman Path Integral methods on quantum particles have different approaches).The paper reveals the widespread misconception in the analysis of YDE and would impact the wave/particle and other YDE interpretations.
In Young's Double Slit Experiment (YDE) and improved versions, waves causing interference travel different distances.As speed of light is constant, waves require different time spans to reach the point of interference.Thereby, if the waves are generated simultaneously at the slits/source, they cannot meet on the screen anywhere outside the mid-line.Formation of fringes is commonly interpreted as interference caused by the meeting (super-positioning) of two waves generated simultaneously.The reality is that fringes are formed by interference of waves generated at different times.However, unless impacted by other phenomena, two waves generated at different times converging to form fringes, as this paper shows, will mandatorily come in same phase to the interference point, producing constructive interference.Interference observed, however, is not only constructive.The effect on the phase of waves while bending (diffraction) is also to be considered.Consequently, it addresses three phenomena causing phase shifts: (1)different starting times,(2)bending at slits, and (3)distances traveled (In contrast, the first two are overlooked by the conventional approach).(Dirac and Feynman Path Integral methods on quantum particles have different approaches).The paper reveals the widespread misconception in the analysis of YDE and would impact the wave/particle and other YDE interpretations.
Young's double slit experiments, which represent the mystery of quantum mechanics, have been described by either the classical wave, or quantum probability waves or pilot waves. Recently, the novel experiments show that the interference patterns of the double slit/cross-double slit experiments may be curved. The previous phenomena of the light bending contain the gravity bending and Airy beam curving transversely. The curved Airy beam is interpreted by the quantum Schrödinger's wave equation and electromagnetic wave theory. To study the curved interference patterns of the comprehensive double slit experiments, we study the underlying physics first, namely, to study whether the light beam/photons behave as wave or as particle before forming the curved interference pattern. In this article, the comprehensive double slit experiments are performed, which show: (1) the fringes of the curved interference pattern are created independently and may be create partially; (2) the longitudinal shield and the metal tube inserted between the slide and the detector has no effect on the interference pattern. The experimental observations suggest that, before forming the curved interference pattern on the detector, photons behave as particles, which can be referred as "wave-particle-coexistence". The phenomena provide the comprehensive information/data for the theoretical study.
3.1 Interference of a Single Photon The kinds of study originally conducted by Thomas Young - in particular, the celebrated "double slit" experiment that we briefly examined in Chapter 1 (see Fig. 1) - provide a capacity to reveal far more than the wave nature of light, important as that is. True enough, the observed characteristic fringe pattern, when monochromatic light passes through two closely spaced slits onto a screen, appears to be simply explicable on the basis of waves from each slit undergoing constructive and destructive interference at different positions on the screen. Yet, astonishingly, these patterns of interference are still exhibited when individual photons of a low-intensity input beam reach the screen one at a time, showing that it cannot in fact be a matter of different photons having to interfere with each other. Indeed, Dirac enunciated the general principle that photons can never directly interact with each other. The double slit and other such experiments indicate that each photon interacts in a delocalized, wave-like manner with both slits at the same time. Successive experiments build interference patterns that conform to an exact mathematical distribution formula, but the position at which an individual photon is detected in any particular instance cannot be predicted; this is a quintessential illustration of quantum uncertainty. Using the path integral approach of quantum theory, the phenomenon is more accurately represented by introducing a summation over all possible routes between the source and the screen on which the pattern appears, signifying an entire "lifetime" for each photon involved in the experiment. This relates to the fact that the actual trajectory is unknown without an observation, and thus we only obtain the probabilities of the photon striking the screen at different positions and times; all trajectories (potentialities) must be considered in a superposition. Each route is considered equally probable, and the variation in phase produces quantum interference. The differences in phase of each trajectory, at varying positions on the screen, generates the fringe pattern. An intriguing variation on this experiment involves "marking" the photons so that the actual route of each photon to the screen is known. Remarkably, in such a case, the fringe patterns do not appear because quantum interference cannot occur. A consequence of the observation of the photon route is an effect that, in other quantum mechanical connections, is known as a collapse of the wavefunction. However, it is possible for the fringe patterns to reappear when information on the route of the photons is lost; this is known as a quantum eraser.
The double slit experiment was first conceived of by the English physician-physicist Thomas Young in 1801. It was the first demonstrative proof that light possesses a wave nature. In this experiment, light is made to pass through two very narrow slits that are spaced closely apart and a screen placed on the other side captures a pattern of alternating bright and dark stripes called fringes, formed as a result of the interference of ripples of light emanating from either slit. The relative positions and intensities of the fringes on the screen can be calculated by employing two assumptions that help simplify the geometry of the slit-screen arrangement. Firstly, the screen to slit distance is taken to be larger than the inter-slit distance (far field limit) and secondly, the inter-slit distance is taken to be larger than the wavelength of light. This conventional approach can account for the positions and intensities of the fringes located in the central portion of the screen with a fair degree of precision. It however, fails to account for those fringes located in the peripheral portions of the screen and also, is not applicable to the case wherein the screen to slit distance is made comparable to the inter-slit distance (near field limit). In this paper, the original analysis of Young’s Experiment is reformulated using an analytically derived hyperbola equation, which is formed from the locus of the points of intersections of two uniformly expanding circular wavefronts of light that emanate from either slit source. Additionally, the shape of the screen used to capture the interference pattern is varied (linear, semicircular, semielliptical) and the relative positions of the fringes is calculated for each case. This new approach bears the distinctive advantage that it is applicable in both the far field and the near field scenarios, and since no assumptions are made beyond the Huygens-Fresnel principle, it is therefore, a much more generalized approach. For these reasons, the author suggests that the new analysis ought to be introduced into the Wave Optics chapter of the undergraduate Physics curriculum.
In 1801, Thomas Young devised what is now known as the Classical Double Slit Experiment. In this experiment, light waves emanating from two separate sources, interfere to form a pattern of alternating bright and dark fringes on a distant screen. By measuring the position of individual fringe centers, the fringe widths and the variation of average light intensity on the screen, it is possible to compute the wavelength of light itself. The original theoretical analysis of the experiment employs a set of geometric assumptions which are collectively referred to here as the Parallel Ray Approximation. Accordingly, any two rays of light arising from either source and convergent on an arbitrary point on the screen, are considered very nearly parallel to each other in the vicinity of the sources. This approximation holds true only when the screen to source distance is very large and the inter-source distance is much larger than the wavelength of light. The predictions that naturally follow are valid only for fringes located near the center of the screen (e.g. the equal spacing of fringes). But for those fringes located further away from the screen center, the precision of these predictions rapidly wanes. Also when the screen to source distance is comparable to the inter-source separation or when the inter-source distance is comparable to the wavelength of light, the original analysis is no longer applicable. In this paper, the theoretical foundations of Young’s experiment are re-formulated using a newly derived analytical equation of a hyperbola, which forms the locus of the points of intersections of two expanding circular wavefronts (with sources located at the respective centers of expansion). The ensuing predictions of the new analysis are compared with those of the old. And finally, it is shown that the latter approach is just a special instance of the former, when the Parallel Ray Approximation can be said to hold true.
Young’s double slit experiments revived the wave theory of light. The standard interpretation is that the light behaves as waves before and after passing through the double slit. Feynman called the double slit experiment the only mystery in quantum mechanics. In this article, we experimentally show the novel universal phenomena: (1) each of the fringes of the interference patterns are produced independently and partially; (2) within macro-distance from a diaphragm, the light rays behave as photons and produces a non-interference pattern; while near the screen, the photons produce an orthogonal interference pattern; (3) The non-interference pattern evolves to the orthogonal interference pattern gradually in the same experiment; (4) The non-interference patterns and the orthogonal interference patterns can show on the screen simultaneously; (5) The convex lens stops the further evolution. The experiments: (1) challenge the wave theories of light; (2) violate both Bohr’s complementarity principle and wave particle duality; (3) provide profound phenomena for developing optics and for studying the nature of light; (4) suggest that a complete theory should be able to consistently interpret all phenomena, including the non-interference pattern, the interference pattern, and the evolution from the non-interference to the interference pattern in the same experiment.
Young’s double slit experiments revived the wave theory of light. The standard interpretation is that the light behaves as waves before and after passing through the double slit. Feynman called the double slit experiment the only mystery in quantum mechanics. By placing a convex lens at different positions, we have shown: (1) Near the diaphragm, light behaves as photons and produces a non-interference pattern; near the screen, the photons produce an interference pattern; (2) The non-interference pattern evolves to the orthogonal interference pattern gradually in the same experiment; (3) The convex lens stops the further evolution. It is heuristic for study the nature of light by showing all of three different kinds of patterns on the screen simultaneously. For this purpose, in this article, we setup three paths. The light is divided into three portions, each portion propagates along one path. Then inserting three lenses to different Zones of different paths. Experiments show that two non-interference patterns and interference pattern simultaneously emerge on the same screen. The experiments: (1) challenge the wave theories of light; (2) violate Bohr’s complementarity principle; (3) provide profound phenomena for further development of optics and for study of the nature of light; (4) suggest that a complete theory should be able to simultaneously interpret the non-interference pattern, the interference pattern, and the evolution from the non-interference to the interference pattern in the same experiment.