redshiftn.
/ˈrɛdʃɪft/, U.S. /ˈrɛdˌʃɪft/ Chiefly Astronomy.
The lengthening of the observed wavelength of light from celestial objects, as discerned from the displacement of spectral lines towards longer wavelengths relative to their position at the time of emission; an instance of this; the ratio of the observed increase in wavelength to the original wavelength, as a measure of this displacement. More widely: any displacement of spectral lines towards longer wavelengths in a spectroscopic context. Cf. blueshift n.In Astronomy the term refers to increases in wavelength due to (a) the Doppler effect when a source is moving away from the observer, (b) the expansion of the universe, and (c) the effect of gravity. The amount of redshift can be used as a measure of the speed of recession of the source (cf. Hubble law n. at Hubble n.) and hence of its distance.In the case of lines in the visible spectrum, an increase in wavelength corresponds to a displacement towards the red, but in the case of wavelengths longer than that of red light, such as microwaves, an increase in wavelength corresponds to displacement away from the red.The concept was described by W. S. Adams in 1908 in connection with the effect of the rotation of the sun on its spectral lines ( Astrophysical Jrnl. 27 213–18), but the term redshift was not used. A ‘shift towards the red’ is mentioned in Astrophysical Jrnl. (1897) 5 210.
ΘΚΠ
the world > the universe > star > star-matter > [noun] > spectrum
spectral type1890
redshift1923
space reddening1931
profile1933
1923 A. S. Eddington Math. Theory Relativity v. 164 The red shift in the spiral nebulae.
1939 Physical Rev. 56 456/1 All energy emitted outward from the surface of the star will be reduced very much in escaping..by the large gravitational red-shift.
1958 Listener 11 Dec. 971/2 As far as we can see, the red shift of the most distant nebulae is still increasing linearly with distance.
1966 D. H. Williams & I. Fleming Spectrosc. Methods in Org. Chem. ii. 38 The absorption maximum of the nitroaniline..is at 385 mμ..showing a red shift and marked reduction in intensity from that of the parent compound..at 375 mμ.
1977 J. Narlikar Struct. Universe vii. 215 When quasi-stellar objects were first discovered, some with red-shifts close to z = 2, it was hoped that they would settle the cosmological issue once for all.
1989 J. Silk Big Bang (rev. ed.) xii. 266 (caption) The cluster is Abell 370 at a redshift of 0.17.
1990 Astronomy Mar. 10/1 The quasar's..redshift is 4.73, which corresponds to a recessional velocity of 94 percent of the speed of light.
1998 Mod. Astronomer Mar. 26/2 The cosmological redshift of galaxies, associated with the expansion of the Universe..is caused by space itself stretching, not by galaxies moving through space.
2007 Tetrahedron 63 2218/2 In water, the formation of solute–solvent hydrogen bonds may explain the significant red shift in emission.
This entry has been updated (OED Third Edition, September 2009; most recently modified version published online March 2022).
redshiftv.
/ˈrɛdʃɪft/, U.S. /ˈrɛdˌʃɪft/ Chiefly Astronomy.
transitive. To displace towards the red end of the spectrum; to cause (electromagnetic radiation) to increase in wavelength. Usually in passive.
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the world > the universe > star > star-matter > [verb (transitive)] > red shift
redshift1959
1959 R. D. Davies & H. P. Palmer Radio Stud. Universe v. 88 Eventually the red-shift becomes so large that most of the energy is red-shifted out of the ultra-violet and visible parts of the spectrum.
1971 Sci. Amer. May 69/1 Light emitted from such an object would have to overcome an immense gravitational potential and would be red-shifted just as it is in quasars.
1988 J. D. Barrow & F. J. Tipler Anthropic Cosmol. Princ. (rev. ed.) iv. 240 His hypothesis..would have observational consequences through redshifting the absorption spectra of distant quasi-stellar radio sources.
2006 J. Lisle Taking back Astron. ii. 30/2 Expansion of the universe can also cause light to be redshifted.
This entry has been updated (OED Third Edition, September 2009; most recently modified version published online March 2022).
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