gravitational redshift


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gravitational redshift

(Einstein shift) The redshift of spectral lines that occurs when radiation, including light, is emitted from a massive body. In order to ‘climb out’ of the body's gravitational field, the radiation must lose energy. The radiation frequency must therefore decrease and its wavelength λ, shift by δλ toward a greater value. The redshift is given by
δλ/λ = Gm /c 2r

G is the gravitational constant, m and r the mass and radius of the massive body, and c is the speed of light. Gravitational redshift was predicted by Einstein's general theory of relativity and although extremely small has been detected, for example, in the spectra of the Sun and several white dwarfs. The redshift of the Earth's gravitational field has been determined very accurately using beams of radiation traveling upward through a tall building. Predicted and measured values agree very closely.

gravitational redshift

[‚grav·ə′tā·shən·əl ′red ‚shift]
(relativity)
A displacement of spectral lines toward the red when the gravitational potential at the observer of the light is greater than at its source.
References in periodicals archive ?
he phenomenon is often called the gravitational redshift because the oscillations of light waves slow down or become redder when tugged by gravity.
In the case of MCG-6-30-15, the gravitational redshift is so extreme, says Fabian, that most of the emission must be coming from the gas and dust extremely close to the black hole.
Calculating the work done by this mass-radiation force on a photon, we can derive the Einsteinian gravitational redshift without using the Einsteinian general relativity
13], which is much smaller than the gravitational redshift [Z.
21) also confirms the use of the constant h in the expression for gravitational redshift,
This, for example, determines the gravitational redshift.
This leads to an expression for gravitational redshift,
An expression for gravitational redshift is derived by accepting the local validity of special relativity at all points in space.
which, to first approximation in exp(-R/2r), gives the observed gravitational redshift.
Calculating the work done by the mass-radiation interaction on a photon, we can derive the Einsteinian gravitational redshift.
The observed redshift from distant sources can be interpreted as (1) a velocity redshift called the Doppler Effect, (2) a cosmological redshift in which space itself is expanding during the transit time of the photons, and/or (3) a gravitational redshift as introduced by the General Theory of Relativity (GTR).
They are: (1) the expanding universe; (2) Doppler redshifts; and (3) gravitational redshifts.