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physical phenomena > process > physical process > optical process > radiation modification > wavelength shift

wavelength shift
subject			fact

wavelength shift	changes property frequency (and wavelength)
	has definition The alteration in frequency of electromagnetic radiation
	is a kind of radiation modification
optical process	has domain optics

Kinds of wavelength shift :

• cosmological redshift (8 facts) (z) - The redshift due to the expansion of the Universe. Contrary to popular belief, this is not a Doppler shift. Most galaxies move away from us, but this is not the cause of their redshifts. Instead, as a light wave travels through the fabric of space, the universe expands and the light wave gets stretched and therefore redshifted.
• Doppler shift (2 kinds, 17 facts) - The alteration in frequency of electromagnetic radiation due to relative motion between the source and observer., The apparent change of frequency or wavelength of radiation from an object due to its motion toward or away from us. If the object is receding the frequency is decreased and the wavelength is increased, i.e. becomes red-shifted., Displacement of spectral lines in the radiation received from a source due to its relative motion along the line of sight. A motion of approach results in a blueshift; a motion of recession results in a redshift., Effect on the wavelengths of light (or sound) emitted by a source at a distance that is increasing or decreasing in relation to the observer. If the distance is increasing, the wavelengths are "stretched" (the light received shifts towards the red end of the spectrum; sound received goes down in pitch). If the distance is increasing, the wavelengths are "squeezed" (the light received shifts towards the blue end of the spectrum; sound received goes up in pitch)., The alteration in frequency of electromagnetic radiation due to relative motion between the source and observer., The change in frequency of a wave (light, sound, etc.) due to the relative motion of source and receiver., The blueshift or redshift produced by an object's motion toward or away from us. If a star moves toward us, its light waves get compressed and its spectrum is blueshifted; if a star moves away from us, its light waves get stretched and its spectrum is redshifted. The Doppler shift allows astronomers to measure the radial velocities of stars. The Doppler shift is not responsible for the redshifts that most galaxies exhibit; that is a cosmological redshift., Change in the apparent wavelength of radiation (e.g., light or sound) emitted by a moving body. A star moving away from the observer will appear to be radiating light at a lower frequency than if at rest; consequently, lines in the star's spectrum will be shifted toward the red (lower frequency) end of the spectrum. The existence of a direct relationship between the redshift of light from galaxies and their distances is the fundamental evidence for the expansion of the universe., Displacement of spectral lines in the radiation received from a source due to its relative motion in the line of sight. Sources approaching (-) the observer are shifted toward the blue; those receding (+), toward the red. The Doppler shift makes it possible to determine the radial velocity and the rotation of stars., The shift in the received frequency and wavelength of a sound wave or electromagnetic wave that occurs when either the source or the observer are in motion. Approach causes a shift toward shorter wavelengths and higher frequencies, called a blueshift. Recession has the opposite effect, called a redshift.
• gravitational redshift (6 facts) (Einstein effect) - The rate at which a clock keeps time when it is in a gravitational field is slower than the rate at which it will keep time in the absence of a gravitational field. (The gravitational redshift was experimentally verified by Pound and Rebka in 1960.) The amount of redshift is directly proportional to the mass of the emitting body and inversely proportional to its radius., Light is emitted at a lower frequency and longer (or redder) wavelength in a gravitational field than in the absence of a gravitational field., Displacement of spectral lines toward longer wavelengths due to the effects of gravity.
• isomer shift (2 facts) - Displacement of an absorption line due to the fact that the absorbing nuclei have a different s-electron density from that of the emitting nuclei.
• Lamb shift (3 facts) - The difference in energy levels of the H atom between 2S_1/2 and 2P₄., A tiny change in the energy of an electron orbiting the nucleus of an atom, caused by the interaction of the electron with other particles that appear and quickly disappear in "quantum fluctuations". (See quantum fluctuations.)