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  2. 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 ...

  3. Presbyopia - Wikipedia

    en.wikipedia.org/wiki/Presbyopia

    Presbyopia is a typical part of the aging process. [4] It occurs due to age related changes in the lens (decreased elasticity and increased hardness) and ciliary muscle (decreased strength and ability to move the lens), causing the eye to focus right behind rather than on the retina when looking at close objects. [4]

  4. List of equations in quantum mechanics - Wikipedia

    en.wikipedia.org/wiki/List_of_equations_in...

    Planck–Einstein equation and de Broglie wavelength relations. P = ( E/c, p) is the four-momentum, K = (ω/ c, k) is the four-wavevector, E = energy of particle. ω = 2π f is the angular frequency and frequency of the particle. ħ = h /2π are the Planck constants. c = speed of light. Schrödinger equation.

  5. Bohr–Sommerfeld model - Wikipedia

    en.wikipedia.org/wiki/Bohr–Sommerfeld_model

    The Bohr–Sommerfeld model (also known as the Sommerfeld model or Bohr–Sommerfeld theory) was an extension of the Bohr model to allow elliptical orbits of electrons around an atomic nucleus. Bohr–Sommerfeld theory is named after Danish physicist Niels Bohr and German physicist Arnold Sommerfeld. Sommerfeld argued that if electronic orbits ...

  6. Prism correction - Wikipedia

    en.wikipedia.org/wiki/Prism_correction

    Thus a prism of 1 Δ would produce 1 cm visible displacement at 100 cm, or 1 meter. This can be represented mathematically as: where is the amount of prism correction in prism dioptres, and is the angle of deviation of the light. For a prism with apex angle and refractive index , .

  7. Anisometropia - Wikipedia

    en.wikipedia.org/wiki/Anisometropia

    The formula for iseikonic lenses (without cylinder) is: = (()) where: t = center thickness (in metres); n = refractive index; P = front base curve (in 1/metres); h = vertex distance (in metres);

  8. Quantum tunnelling - Wikipedia

    en.wikipedia.org/wiki/Quantum_tunnelling

    Introduction to the concept. Quantum tunnelling falls under the domain of quantum mechanics. To understand the phenomenon, particles attempting to travel across a potential barrier can be compared to a ball trying to roll over a hill. Quantum mechanics and classical mechanics differ in their treatment of this scenario.

  9. List of unsolved problems in physics - Wikipedia

    en.wikipedia.org/wiki/List_of_unsolved_problems...

    List of unsolved problems in physics. The following is a list of notable unsolved problems grouped into broad areas of physics. [1] Some of the major unsolved problems in physics are theoretical, meaning that existing theories seem incapable of explaining a certain observed phenomenon or experimental result. The others are experimental, meaning ...

  10. Esophoria - Wikipedia

    en.wikipedia.org/wiki/Esophoria

    Esophoria is an eye condition involving inward deviation of the eye, usually due to extra-ocular muscle imbalance. It is a type of heterophoria. Cause. Causes include: Refractive errors; Divergence insufficiency; Convergence excess; this can be due to nerve, muscle, congenital or mechanical anomalies.

  11. Loop quantum gravity - Wikipedia

    en.wikipedia.org/wiki/Loop_quantum_gravity

    e. Loop quantum gravity ( LQG) is a theory of quantum gravity that incorporates matter of the Standard Model into the framework established for the intrinsic quantum gravity case. It is an attempt to develop a quantum theory of gravity based directly on Albert Einstein's geometric formulation rather than the treatment of gravity as a mysterious ...