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Time-Varying Fields
Published in Ahmad Shahid Khan, Saurabh Kumar Mukerji, Electromagnetic Fields, 2020
Ahmad Shahid Khan, Saurabh Kumar Mukerji
The Michelson–Morley experiment was designed to detect second order effects of the “ether wind”, i.e. the motion of the ether relative to the Earth. Michelson designed an instrument called the Michelson interferometer to accomplish this. The apparatus was more than accurate enough to detect the expected effects, but he obtained a null result when the first experiment was conducted in 1881,11 and again in 1887.12 Although the failure to detect an ether wind was a disappointment, the results were accepted by the scientific community.13 In an attempt to salvage the ether paradigm, Fitzgerald and Lorentz independently proposed that the length of material bodies changes according to their motion through the ether,13 as given below: l=lo⋅1−β2
Consolidation and skills development
Published in Andrew Norton, Dynamic Fields and Waves, 2019
The Doppler effect describes the change in frequency which occurs when there is motion of either the wave source or the observer. For sound waves, motion of either the source or the observer, relative to the air through which the wave propagates, leads to such a frequency shift, as derived in Chapter 2. The speed of light c arises naturally in Maxwell’s equations, leading to the nineteenth-century idea that light propagates with speed c through a hypothetical medium called the ether. The Michelson-Morley experiment tried to measure the motion of the Earth relative to this ether, and arrived instead at the conclusion that there is no stationary ether through which light propagates. Contrary to nineteenth-century expectations, the speed of light is a fundamental constant: all observers will always measure the speed of light in a vacuum to have the value c = 3.00 × 108 m s−1.
Optical Interference
Published in Rajpal S. Sirohi, Optical Methods of Measurement, 2018
Two-beam interferometers using division of wavefront have been used for the determination of the refractive index (Rayleigh interferometer), determination of the angular size of distant objects (Michelson stellar interferometer), deformation studies (speckle interferometers), and so on. Interferometers based on division of amplitude are used for the determination of wavelength (Michelson interferometer), the testing of optical components (Twyman–Green interferometer, Zygo interferometer, Wyco interferometer, and shear interferometers), the study of microscopic objects (Mirau interferometer), the study of birefringent objects (polarization interferometers), distance measurement (modified Michelson interferometer), and so on. The Michelson interferometer is also used in spectroscopy, particularly in the infrared region, and offers Fellgett’s advantage. The Michelson–Morley experiment, which used a Michelson interferometer to show the absence of the ether, played a great part in the advancement of science. Gratings are also used as beam-splitters and beam-combiners. Because of their dispersive nature, they are used in the construction of achromatic interferometers.
Travelling light
Published in Journal of Modern Optics, 2021
If this explanation is correct, the Michelson-Morley experiment and others like it will never reveal the absolute velocity of the earth, because the light that they depend on has been velocity-adjusted by the earth’s gravitational field. However, an experiment of this sort could reveal the absolute velocity of the experimental apparatus if the experiment were done somewhere in outer space where the gravitational environment is friendlier. I am being intentionally vague here because I have no idea what the criterion for a friendly gravitational environment would be.
A hypothesis for the architecture of plant secondary cell walls, involving liquid crystalline arrays of microtubules in the cortex of the cell
Published in Liquid Crystals, 2021
The remarkable optical properties of this iridescent phase (i.e. the colour and the selective reflection of circularly polarised light) were found to be the same as those of iridescent insect cuticles, which had been previously studied by Michelson [17] (of Michelson / Morley experiment fame [18] and were identified as being produced by a helicoidal structure as sketched in Figure 6.