Calculating Wavelengths of Redshift in Cosmology

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Discussion Overview

The discussion centers on the calculations of wavelengths associated with cosmological redshift, exploring the relationship between emitted and received wavelengths in the context of the universe's expansion. Participants seek to clarify the specific wavelengths that correspond to different redshift values and the underlying principles governing these calculations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant inquires about the precise wavelengths that determine various redshift values, indicating a desire for comprehensive information on the topic.
  • Another participant suggests that the calculation of redshift is straightforward and applies uniformly across all wavelengths, depending on the ratio of wavelengths received to emitted.
  • The formula for redshift is presented as z+1 = (wavelength received)/(wavelength emitted), which is linked to the expansion of the universe during the light's transit.
  • There is a mention of specific spectral lines from chemical elements, such as hydrogen and sodium, as potentially relevant to the discussion of redshift.
  • A later reply expresses a desire for more information on the different spectral lines of various chemical elements, indicating an interest in the specifics of how these relate to redshift.

Areas of Agreement / Disagreement

Participants appear to have differing levels of understanding regarding the specifics of redshift calculations and the relevance of spectral lines, but there is no clear consensus on the exact details or implications of these calculations.

Contextual Notes

Some assumptions about the nature of the scalefactor and its role in redshift calculations are present, but these are not fully explored or defined in the discussion.

Paul_Stone
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[i asked this question in my blog..but i know it would be better answered here]

what are the calculations of the wave lengths of a cosmological redshift?

(meaning them all)

i just wanted to know what precises wavelength determines which red shift..

thanks guys
 
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Paul_Stone said:
[i asked this question in my blog..but i know it would be better answered here]

what are the calculations of the wave lengths of a cosmological redshift?

(meaning them all)

i just wanted to know what precises wavelength determines which red shift..

thanks guys


I'm not sure what it is you want to find out. Do you want to know the various spectral lines of specific chemical elements (like hydrogen alpha line, or sodium yellow, or iron...)?

The calculation is very simple and is the same for every wavelength---every color.

The light's wavelength will be increased by a ratio (Z+1) that is the same for all colors and depends only on the time the light was emitted and the time it was received

The ratio z+1 = (wavelength received)/(wavelength emitted)
is always equal to the ratio by which the universe expanded during the time that the light was in transit.

z+1 = (size when light is received)/(size when light was emitted)

By "size" here I mean a quantity called the scalefactor which tracks the expansion of distances, the expansion of the universe. Think of it as the size of the universe if that were finite and we were able to determine it.
 
marcus said:
I'm not sure what it is you want to find out. Do you want to know the various spectral lines of specific chemical elements (like hydrogen alpha line, or sodium yellow, or iron...)?

The calculation is very simple and is the same for every wavelength---every color.

The light's wavelength will be increased by a ratio (Z+1) that is the same for all colors and depends only on the time the light was emitted and the time it was received

The ratio z+1 = (wavelength received)/(wavelength emitted)
is always equal to the ratio by which the universe expanded during the time that the light was in transit.

z+1 = (size when light is received)/(size when light was emitted)

By "size" here I mean a quantity called the scalefactor which tracks the expansion of distances, the expansion of the universe. Think of it as the size of the universe if that were finite and we were able to determine it.


oh yeah..i should have been a little more specific..yeah i wanted to know the different spectral lines of each different periodic chemical..

but what you just said helped..thanks

any more information..send it my way.

later
 

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