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  2. Free-air gravity anomaly - Wikipedia

    en.wikipedia.org/wiki/Free-air_gravity_anomaly

    The free air correction is calculated from Newton's Law, as a rate of change of gravity with distance: g = G M R 2 d g d R = − 2 G M R 3 = − 2 g R {\displaystyle {\begin{aligned}g&={\frac {GM}{R^{2}}}\\{\frac {dg}{dR}}&=-{\frac {2GM}{R^{3}}}=-{\frac {2g}{R}}\end{aligned}}}

  3. Prism correction - Wikipedia

    en.wikipedia.org/wiki/Prism_correction

    Prentice's rule, named so after the optician Charles F. Prentice, is a formula used to determine the amount of induced prism in a lens: = where: P is the amount of prism correction (in prism dioptres) c is decentration (the distance between the pupil centre and the lens's optical centre, in millimetres)

  4. Dioptre - Wikipedia

    en.wikipedia.org/wiki/Dioptre

    A dioptre ( British spelling) or diopter ( American spelling ), symbol dpt, is a unit of measurement with dimension of reciprocal length, equivalent to one reciprocal metre, 1 dpt = 1 m−1. It is normally used to express the optical power of a lens or curved mirror, which is a physical quantity equal to the reciprocal of the focal length ...

  5. Gibbs paradox - Wikipedia

    en.wikipedia.org/wiki/Gibbs_paradox

    Removing or reinserting the wall is reversible, but the entropy increases when the barrier is removed by the amount. which is in contradiction to thermodynamics if you re-insert the barrier. This is the Gibbs paradox. The paradox is resolved by postulating that the gas particles are in fact indistinguishable.

  6. 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.

  7. 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 ...

  8. Einstein field equations - Wikipedia

    en.wikipedia.org/wiki/Einstein_field_equations

    v. t. e. In the general theory of relativity, the Einstein field equations ( EFE; also known as Einstein's equations) relate the geometry of spacetime to the distribution of matter within it. [1] The equations were published by Albert Einstein in 1915 in the form of a tensor equation [2] which related the local spacetime curvature (expressed by ...

  9. Aberration (astronomy) - Wikipedia

    en.wikipedia.org/wiki/Aberration_(astronomy)

    Aberration (astronomy) A diagram showing how the apparent position of a star viewed from the Earth can change depending on the Earth's velocity. The effect is typically much smaller than illustrated. In astronomy, aberration (also referred to as astronomical aberration, stellar aberration, or velocity aberration) is a phenomenon where celestial ...

  10. Debye model - Wikipedia

    en.wikipedia.org/wiki/Debye_model

    Combining this formula with the expected energy of a harmonic oscillator at temperature (already used by Einstein in his model) would give an energy of U = ∫ 0 ∞ h ν 3 V F e h ν / k T − 1 d ν , {\displaystyle U=\int _{0}^{\infty }\,{h u ^{3}VF \over e^{h u /kT}-1}\,d u \,,}

  11. Schrödinger equation - Wikipedia

    en.wikipedia.org/wiki/Schrödinger_equation

    Linearity. The Schrödinger equation is a linear differential equation, meaning that if two state vectors and are solutions, then so is any linear combination. of the two state vectors where a and b are any complex numbers. [13] : 25 Moreover, the sum can be extended for any number of state vectors.