SkipCaptcha
1,279
edits
Changes
Jump to navigation
Jump to search
Line 1:
Line 1: − + + + + + + + + + + + + + + +
Add a section giving formulae relevant to redshift
The '''redshift''' of a given object is a measure of the amount that the wavelength of its emitted or reflected electromagnetic radiation has increased. This increase in wavelength is prevailingly interpreted as due to the relative motion of a source with respect to an [[Scientific observation|observer]]; a [[light]] emitting source moving away from an observer will have its spectrum shifted toward longer (in optical light, redder) wavelengths. In practice this is analogous to the [[Doppler effect|Doppler shifting]] of sound waves emitted from a moving source. Light emitted from a source moving towards an observer will experience a blueshift. In the case of redshift, however, most of the redshift is believed to be due not to the object moving through space, but to the expansion of space itself.
The '''redshift''' of a given object is a measure of the amount that the [[wavelength]] of its emitted or reflected electromagnetic radiation has increased.<ref name=britannica>{{cite web|url=https://www.britannica.com/science/redshift|title=Redshift|accessdate=2019-04-02}}</ref> This increase in wavelength is prevailingly interpreted as due to the relative motion of a source with respect to an [[Scientific observation|observer]]; a [[light]] emitting source moving away from an observer will have its spectrum shifted toward longer (in optical light, redder) wavelengths. In practice this is analogous to the [[Doppler effect|Doppler shifting]] of sound waves emitted from a moving source. Light emitted from a source moving towards an observer will experience a blueshift. In the case of redshift, however, most of the redshift is believed to be due not to the object moving through space, but to the expansion of space itself.
==Mathematics==
The redshift, ''Z'', of an object as measured by an observer is defined as,<ref name=swin>{{cite web|url=http://astronomy.swin.edu.au/cosmos/c/cosmological+redshift|title=Cosmological Redshift|accessdate=2019-04-02}}</ref>
:<math>
1 + Z \equiv \frac{\lambda_\mathrm{observed}}{\lambda_\mathrm{emitted}}
</math>
where the <math>\lambda_\mathrm{emitted}</math> is the wavelength of light emitted by the object and <math>\lambda_\mathrm{observed}</math> is the wavelength measured by the observed. The recessional velocity, ''v'', of an object can be determined from its redshift to be,<ref>{{cite web|url=http://hyperphysics.phy-astr.gsu.edu/hbase/Astro/redshf.html|title=Red shift|accessdate=2019-04-02}}</ref>
:<math>
\frac{v}{c} = \frac{(z+1)^2 - 1}{(z+1)^2 + 1}
</math>
where ''c'' is the [[speed of light]]. At small recessional velocities/redshifts, the formula can be simplified to,<ref name=swin/>
:<math>
z \approx \frac{v}{c}
</math>
== Support for the Big Bang theory ==
== Support for the Big Bang theory ==