Redshift - Revision history

FredericBernard: Wikify

2019-04-02T17:55:46Z

Wikify

FredericBernard: Add a section giving formulae relevant to redshift

2019-04-02T16:50:21Z

Add a section giving formulae relevant to redshift

FredericBernard: Fix broken link, tidy up math, wikify

2019-03-27T14:30:54Z

Fix broken link, tidy up math, wikify

FredericBernard: Fix broken link

2019-03-27T14:21:26Z

Fix broken link

DavidB4-bot: /* See also */clean up & uniformity

2016-07-13T18:17:40Z

AK: adding text on alternative interpretations -to be continued

2013-06-23T17:04:37Z

adding text on alternative interpretations -to be continued

AK: internal links

2013-06-19T06:15:03Z

internal links

AK: Fixing dead link and adding See also section

2013-06-09T09:55:02Z

Fixing dead link and adding See also section

DavidZa: That sort of claim requires a citation

2011-09-29T21:21:14Z

That sort of claim requires a citation

JimJast: /* Support for the Big Bang theory */

2011-09-29T20:52:50Z

Support for the Big Bang theory

← Older revision		Revision as of 17:55, April 2, 2019
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−	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.	+	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 [[visible light\|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==		==Mathematics==

← Older revision		Revision as of 16:50, April 2, 2019
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−	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 ==

@@ Line 5: / Line 5: @@
 The Hubble redshift in absorption and emission lines in the spectra of distant cosmic objects, discovered by [[Edwin Hubble]] in 1929, is claimed as a source of evidence for the [[Big Bang theory]].<ref>{{cite web |title=A relation between distance and radial velocity among extra-galactic nebulae |author=Edwin Hubble |date=January 17, 1929 |publisher=Proceedings of the National Academy of Sciences |pages=15: 168–173|url=http://www.pnas.org/content/15/3/168.short |accessdate=June 9, 2013}}</ref> The redshift, the expanded wavelength of light, suggests that these objects are moving away from Earth due to the [[Expanding universe|expansion of the universe]]. It also suggests that the universe is undergoing accelerating expansion for an unknown reason.
-Actually the reason is known and confirmed by Supernova Cosmology Project team in 1998 with accuracy to one standard deviation (the second term of Taylor series of Hubble "constant" as function of time is causing the illusion of accelerating expansion of space with
+Actually the reason is known and confirmed by Supernova Cosmology Project team in 1998 with accuracy to one standard deviation (the second term of [[Taylor series]] of Hubble "constant" as function of time is causing the illusion of accelerating expansion of space with
-:<math>dH/dt=-H_o^2/2</math>,
+:<math>\frac{\mathrm{d}H}{\mathrm{d}t}=-\frac{H_o^2}{2}</math>,
-where <math>dH/dt</math> is apparent acceleration of expansion of space,
+where <math>{\mathrm{d}H} / {\mathrm{d}t}</math> is apparent acceleration of expansion of space,
-:<math>H_o=c/R_E</math>,
+:<math>H_o=\frac{c}{R_E}</math>,
-is Hubble constant, <math>c</math> is speed of light in [[vacuum]], and <math>R_E</math> is "Einstein radius", or radius of [[curvature of space]], about 13 billion light years).
+is Hubble constant, ''c'' is [[speed of light]] in [[vacuum]], and ''R''<sub>E</sub> is "Einstein radius", or radius of [[curvature of space]], about 13 billion light years).
 ==Alternative Interpretations of the Redshift==
 The redshift phenomenon pertains to observation of spectra of [[light]] emitted from luminous bodies such as [[nebulae]] (stellar systems). The true nature of light is however still uncertain. With current body of knowledge, the light can be portrayed as out-spreading electromagnetic wave or as travelling in bullet-like parcels of energy called quanta. Waves have various wavelengths; quanta carry different amounts of energy. Since the same phenomenon can be described by both concepts, it is regarded as evidence that there is some underlying connection between them. This connection is expressed in the very fundamental relation between the energy-content of a quantum and the equivalent wavelength:
 :''energy x wavelength = constant''
-:<math>E{\lambda} = constant</math>
+:<math>E{\lambda} = \mathrm{constant}</math>
 Because of this relation, two possible effects can be identified:
-*a.) Increase of wavelength <math>{\lambda}</math> implies => a decrease in Energy E; If the primary change is in wavelength, then the red-shifts are probably velocity-shifts, what is nowadays prevailing interpretation.
+*a.) Increase of wavelength <math style="vertical-align:-10%;">{\lambda}</math> implies a decrease in Energy ''E''; If the primary change is in wavelength, then the red-shifts are probably velocity-shifts, what is nowadays prevailing interpretation.
-*b.) Reduction of Energy E implies => an increase of wavelength <math>{\lambda}</math>; The primary change might be also a loss of energy, which would be observed as redshift.
+*b.) Reduction of Energy ''E'' implies an increase of wavelength <math style="vertical-align:-10%;">{\lambda}</math>; The primary change might be also a loss of energy, which would be observed as redshift.
 As in either case it is only increased wavelength what is observed, there is no direct way of determining which of the two above effects is fundamental.
 In order to be able to distinguish between two alternatives, a critical empirical test is needed that would establish whether or not a luminous body is receding.<ref name="Observational Approach">{{cite web
@@ Line 41: / Line 41: @@
 [[Category:Astronomy]]

← Older revision		Revision as of 14:21, March 27, 2019
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−	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 ~~shift~~]]~~ing~~ 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. 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.

	== Support for the Big Bang theory ==		== Support for the Big Bang theory ==

@@ Line 27: / Line 27: @@
 |access date=27.09.2012}}</ref>
-==See Also==
+==See also==
 *[[Expanding universe]]
 *[[Cosmological constant]]
 *[[Hubble Law]]
-[[Category: Astronomy]]
+[[Category:Astronomy]]
-[[Category: Cosmology]]
+[[Category:Cosmology]]
-[[Category: Physics]]
+[[Category:Physics]]
 ==References==

@@ Line 1: / Line 1: @@
-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 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 shift]]ing 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. 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 shift]]ing 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.
 == Support for the Big Bang theory ==
@@ Line 11: / Line 11: @@
 is Hubble constant, <math>c</math> is speed of light in [[vacuum]], and <math>R_E</math> is "Einstein radius", or radius of [[curvature of space]], about 13 billion light years).
 ==See Also==
 *[[Expanding universe]]

@@ Line 3: / Line 3: @@
 == Support for the Big Bang theory ==
-The Hubble redshift in absorption and emission lines in the spectra of distant cosmic objects, discovered by Edwin Hubble in 1929, is claimed as a source of evidence for the [[Big Bang theory]].<ref>Edwin Hubble (1929). [http://www.pnas.org/cgi/reprint/15/3/168/ "A relation between distance and radial velocity among extra-galactic nebulae"]. Proceedings of the National Academy of Sciences 15: 168–173.</ref> The redshift, the expanded wavelength of light, suggests that these objects are moving away from Earth due to the expansion of the universe. It also suggests that the universe is undergoing accelerating expansion for an unknown reason.
+The Hubble redshift in absorption and emission lines in the spectra of distant cosmic objects, discovered by Edwin Hubble in 1929, is claimed as a source of evidence for the [[Big Bang theory]].<ref>{{cite web |title=A relation between distance and radial velocity among extra-galactic nebulae |author=Edwin Hubble |date=January 17, 1929 |publisher=Proceedings of the National Academy of Sciences |pages=15: 168–173|url=http://www.pnas.org/content/15/3/168.short |accessdate=June 9, 2013}}</ref> The redshift, the expanded wavelength of light, suggests that these objects are moving away from Earth due to the expansion of the universe. It also suggests that the universe is undergoing accelerating expansion for an unknown reason.
 Actually the reason is known and confirmed by Supernova Cosmology Project team in 1998 with accuracy to one standard deviation (the second term of Taylor series of Hubble "constant" as function of time is causing the illusion of accelerating expansion of space with
@@ Line 10: / Line 10: @@
 :<math>H_o=c/R_E</math>,
 is Hubble constant, <math>c</math> is speed of light in vacuum, and <math>R_E</math> is "Einstein radius", or radius of curvature of space, about 13 billion light years).
 [[Category: Astronomy]]

← Older revision		Revision as of 20:52, September 29, 2011
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	The Hubble redshift in absorption and emission lines in the spectra of distant cosmic objects, discovered by Edwin Hubble in 1929, is claimed as a source of evidence for the [[Big Bang theory]].<ref>Edwin Hubble (1929). [http://www.pnas.org/cgi/reprint/15/3/168/ "A relation between distance and radial velocity among extra-galactic nebulae"]. Proceedings of the National Academy of Sciences 15: 168–173.</ref> The redshift, the expanded wavelength of light, suggests that these objects are moving away from Earth due to the expansion of the universe. It also suggests that the universe is undergoing accelerating expansion for an unknown reason.		The Hubble redshift in absorption and emission lines in the spectra of distant cosmic objects, discovered by Edwin Hubble in 1929, is claimed as a source of evidence for the [[Big Bang theory]].<ref>Edwin Hubble (1929). [http://www.pnas.org/cgi/reprint/15/3/168/ "A relation between distance and radial velocity among extra-galactic nebulae"]. Proceedings of the National Academy of Sciences 15: 168–173.</ref> The redshift, the expanded wavelength of light, suggests that these objects are moving away from Earth due to the expansion of the universe. It also suggests that the universe is undergoing accelerating expansion for an unknown reason.
		+
		+	Actually the reason is known and confirmed by Supernova Cosmology Project team in 1998 with accuracy to one standard deviation (the second term of Taylor series of Hubble "constant" as function of time is causing the illusion of accelerating expansion of space with
		+	:<math>dH/dt=-H_o^2/2</math>,
		+	where <math>dH/dt</math> is apparent acceleration of expansion of space,
		+	:<math>H_o=c/R_E</math>,
		+	is Hubble constant, <math>c</math> is speed of light in vacuum, and <math>R_E</math> is "Einstein radius", or radius of curvature of space, about 13 billion light years). Scientific journals are niether publishing it nor allow to put it through peer review process. If they did then the Big Bang hypothesis would collapse which might harm [[relativists]].

	[[Category: Astronomy]]		[[Category: Astronomy]]