Classical mechanics and geometric optics are the most common and extreme high frequency approximation, where the wave or field properties of, respectively, quantum mechanics and electromagnetism are neglected entirely. Classical mechanics is a branch of physics which studies the deterministic motion of objects. ... See also list of optical topics. ... Fig. ... Electromagnetism is the physics of the electromagnetic field; a field encompassing all of space which exerts a force on particles that possess the property of electric charge, and is in turn affected by the presence and motion of those particles. ...
Less extreme approximations include, the WKB approximation, physical optics, the geometric theory of diffraction, the uniform theory of diffraction, and the physical theory of diffraction. When these are used to approximate quantum mechanics are called semiclassical. In physics, the WKB (Wentzel-Kramers-Brillouin) approximation, also known as WKBJ approximation, is the most familiar example of a semiclassical calculation in quantum mechanics in which the wavefunction is recast as an exponential function, semiclassically expanded, and then either the amplitude or the phase is taken to be slowly... Physical Optics is the name of a high frequency approximation (short wavelength approximation) used in the electromagnetism of optics and radio. ... In numerical analysis, the Uniform Theory of Diffraction or UTD is a high frequency method for solving Electromagnetic scattering problems from electrically small discontinuities or discontinuities in more that one dimension at the same point. ... Fig. ... In physics, the adjective semiclassical has different precise meanings depending on the context. ...
A highfrequencyapproximation (or "high energy approximation") for scattering or other wave propagation problems, in physics or engineering, is an approximation whose accuracy increases with the size of features on the scatterer or medium relative to the wavelength of the scattered particles.
Classical mechanics and geometric optics are the most common and extreme highfrequencyapproximation, where the wave or field properties of, respectively, quantum mechanics and electromagnetism are neglected entirely.
Less extreme approximations include, the WKB approximation, physical optics, the geometric theory of diffraction, the uniform theory of diffraction, and the physical theory of diffraction.
First, semiclassical approximation may refer to quantum-mechanical calculations that are obtained by considering a small perturbation of a classical calculation, for example the WKB approximation in non-relativistic quantum mechanics or the loop expansion or the instanton methods in quantum field theory.
Third, semiclassical gravity is the approximation to the yet unknown theory of quantum gravity in which one treats matter fields as being quantum and the gravitational field as being classical.
A semiclassical approximation is any highfrequencyapproximation (or "high energy approximation"), less extreme than classical mechanics, that is used to approximate quantum mechanics.
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