Redshift

:This article is about the light phenomenon. For other uses of the phrase "Red Shift", see Red Shift

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Redshift describes a change in the wavelength of light, in which the wavelength is longer, or redder, than when it was emitted at the source. This can happen when the source moves away from the observer, known as the Doppler effect. It is also observed when light emitted by distant galaxies is shifted to longer wavelengths than the spectrum of closer galaxies. This is taken as evidence that the universe is expanding and that it started in a Big Bang.

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In general, redshift (and blueshift, the observation of shorter wavelength light than emitted) is quantified by

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z = rac{f_{mathrm{emitted}} - f_{mathrm{observed}}}{f_{mathrm{observed}}} = rac{lambda_{mathrm{observed}} - lambda_{mathrm{emitted}}}{lambda_{mathrm{emitted}}}

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where f is frequency and λ is wavelength.

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Light: Light is electromagnetic radiation with a wavelength that is visible to the eye (visible light) or, in a technical or scientific setting, electromagnetic radiation of any wavelength. The three basic dimensions of light (i.e., all electromagnetic radiation) are:...

Doppler effect: The Doppler effect, named after Christian Andreas Doppler, is the apparent change in frequency or wavelength of a wave that is perceived by an observer moving relative to the source of the waves. For waves, such as sound waves, that propagate in a wave medium, the velocity of the observer and the s...

Galaxies: REDIRECT Galaxy...