What is redshift?

  • (noun): (astronomy) a shift in the spectra of very distant galaxies toward longer wavelengths (toward the red end of the spectrum); generally interpreted as evidence that the universe is expanding.

Redshift

In physics (especially astrophysics), redshift happens when light seen coming from an object that is moving away is proportionally increased in wavelength, or shifted to the red end of the spectrum. More generally, where an observer detects electromagnetic radiation outside the visible spectrum, "redder" amounts to a technical shorthand for "increase in electromagnetic wavelength" — which also implies lower frequency and photon energy in accord with, respectively, the wave and quantum theories of light.

Read more about Redshift.

Some articles on redshift:

The Hubble Constant - Interpretation - Redshift Velocity and Recessional Velocity
... Redshift can be measured by determining the wavelength of a known transition, such as hydrogen α-lines for distant quasars, and finding the fractional shift compared to a stationary reference ... Thus redshift is a quantity unambiguous for experimental observation ... The relation of redshift to recessional velocity is another matter ...
Lyman-alpha Emitter
... which may be interpreted as their redshift where z is the redshift, is the observed wavelength, and 1215.67 Å is the wavelength of Lyman-alpha emission ... Experimental observations of the redshift of LAEs are important in cosmology because they trace dark matter halos and subsequently the evolution of matter distribution in the ...
Redshift - Effects Due To Physical Optics or Radiative Transfer
... phenomena are sometimes referred to as "redshifts" and "blueshifts", in astrophysics light-matter interactions that result in energy shifts in the radiation field are ...
Blue Shift
... (increase in frequency) the opposite effect is referred to as redshift ... by General Relativity in the same way as gravitational redshift ... cosmological blueshift would be observed the expanding universe gives a cosmological redshift, and the expansion is observed to be accelerating ...
William G. Tifft
... main interests are in galaxies, superclusters and what Tifft calls redshift problems (see redshift quantization) ... He was influential in the development of the first redshift surveys and was an early proponent of manned space astronomy, conducted at a proposed moon base for example ...