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  2. Prism correction - Wikipedia

    en.wikipedia.org/wiki/Prism_correction

    Prism correction is commonly specified in prism dioptres, a unit of angular measurement that is loosely related to the dioptre. Prism dioptres are represented by the Greek symbol delta (Δ) in superscript. A prism of power 1 Δ would produce 1 unit of displacement for an object held 100 units from the prism. [2]

  3. Perturbation theory (quantum mechanics) - Wikipedia

    en.wikipedia.org/wiki/Perturbation_theory...

    In quantum mechanics, perturbation theory is a set of approximation schemes directly related to mathematical perturbation for describing a complicated quantum system in terms of a simpler one. The idea is to start with a simple system for which a mathematical solution is known, and add an additional "perturbing" Hamiltonian representing a weak ...

  4. Bethe–Salpeter equation - Wikipedia

    en.wikipedia.org/wiki/Bethe–Salpeter_equation

    The equation was first published in 1950 at the end of a paper by Yoichiro Nambu, but without derivation. A graphical representation of the Bethe–Salpeter equation, showing its recursive definition. Due to its generality and its application in many branches of theoretical physics, the Bethe–Salpeter equation appears in many different forms.

  5. Quantum electrodynamics - Wikipedia

    en.wikipedia.org/wiki/Quantum_electrodynamics

    e. In particle physics, quantum electrodynamics ( QED) is the relativistic quantum field theory of electrodynamics. [1] [2] [3] In essence, it describes how light and matter interact and is the first theory where full agreement between quantum mechanics and special relativity is achieved. [2]

  6. Fine structure - Wikipedia

    en.wikipedia.org/wiki/Fine_structure

    Fine structure. Interference fringes, showing fine structure (splitting) of a cooled deuterium source, viewed through a Fabry–Pérot interferometer. In atomic physics, the fine structure describes the splitting of the spectral lines of atoms due to electron spin and relativistic corrections to the non-relativistic Schrödinger equation.

  7. Two-body problem in general relativity - Wikipedia

    en.wikipedia.org/wiki/Two-body_problem_in...

    v. t. e. The two-body problem in general relativity (or relativistic two-body problem) is the determination of the motion and gravitational field of two bodies as described by the field equations of general relativity. Solving the Kepler problem is essential to calculate the bending of light by gravity and the motion of a planet orbiting its sun.

  8. Geometrical optics - Wikipedia

    en.wikipedia.org/wiki/Geometrical_optics

    Geometrical optics, or ray optics, is a model of optics that describes light propagation in terms of rays. The ray in geometrical optics is an abstraction useful for approximating the paths along which light propagates under certain circumstances. The simplifying assumptions of geometrical optics include that light rays: propagate in straight ...

  9. Achromatic lens - Wikipedia

    en.wikipedia.org/wiki/Achromatic_lens

    In an achromatic lens, two wavelengths are brought into the same focus, here red and blue. An achromatic lens or achromat is a lens that is designed to limit the effects of chromatic and spherical aberration. Achromatic lenses are corrected to bring two wavelengths (typically red and blue) into focus on the same plane.