Talk:List of refractive indices

message: How does a pair of two different physical properties--refractive index and absorptivity--constitute a complex number?  Was this concept taken from scientific literature, or from the mind of a creative contributor?  It reminds me of Hawking's "complex time".  I would rewrite this myself, but I see the person who added it is a professor of Applied Math and has a background in Physics, so I'll leave it up to him.
:It is completely standard; look in any textbook.  Because Maxwell's equations are linear (for linear materials), it is correct and convenient to write oscillatory fields with a time-dependence exp(-iωt) instead of with cos or sin (with the understanding that the "physical" solution is the real part of this).  Then, in a uniform medium, the spatial dependence becomes exp(iωx * n/c), where n is the index.  Thus, the real part of n gives an oscillatory term, and the imaginary part gives an exponential decay.  Equivalently, if you look at how the conductivity σ of a material enters Maxwell's equations, it can be equated with an imaginary dielectric constant ε=iσ/ω for  time-harmonic exp(-iωt) fields. —Steven G. Johnson 17:22, Apr 7, 2005 (UTC)
: Stevnj is correct. I'm more familiar with the complex representation manifesting itself as complex permittivity or a complex impedance, but not of free space, here is the reference article. Impedance of free space. Gfutia 22:39, 6 October 2007 (UTC)
thread_title: Complex Number?

message: Someone said that through refraction, it is the speed (so the wavelength) which modifies, not the frequency.
If that's so, I think it would be more accurate to give the frequency of the wave as related value, not the wavelength.
:When people give a wavelength associated with an index of refraction, they normally mean the frequency associated with that wavelength in vacuum.  (You're right that the wavelength changes inside a material, whereas the frequency is preserved.  However, the vacuum wavelength is much more conventional to give at infrared and higher frequencies.  A note about this in the article would be nice, or perhaps just a link to vacuum wavelength.) —Steven G. Johnson 21:50, Jun 10, 2005 (UTC)
:: Are you sure about this statement. "The wavelength changes in side of the material, where as the frequency is preserved?" I agree that wavelengths should also be given for each measurements since due to dispersion (optics) the index of refraction is dependent of the frequency/wavelength of the light. Gfutia 22:34, 6 October 2007 (UTC)
replies: text:  Yea. Wavelength means wavelength in vacuum. It does change in media but in terms of light wavelength(in vacuum) is what everyone uses this to discuss light frequencies. Everyone knows 500 (nm) light is green light, no one coverts this to frequency, f = c/lambda and calls it 600,000,000,000,000 Hz = 600 PHz light. Gfutia (talk) 06:33, 20 February 2013 (UTC)
thread_title:  wavelength or frequency ? 

message: Could someone add information to this page and to lead crystal about the index of leaded glass? —Ben FrantzDale 20:31, 5 June 2006 (UTC)
replies: text: If your think the information belongs on this page, you should find a source for the information and add it. Gfutia 22:34, 6 October 2007 (UTC)
thread_title: Crystal

message: After reading the discussion page for this article, I searched for a better source of information regarding refractive indices. I found a site that gave a few formulas to calculate the index of refraction. I recommend including the formulas in the article or listing the site under 'external links'
http://emtoolbox.nist.gov/Wavelength/Documentation.asp
Smithg86 19:25, 22 September 2007 (UTC)
replies: text: If you think this is of value, you should include it in the article. Gfutia 22:34, 6 October 2007 (UTC)

text: External links are not references. Gfutia 22:34, 6 October 2007 (UTC)
thread_title:  A better source of information? 

message: === Addition of the wavelength columns ===
The refractive index of materials is dependent on the wavelength used for measurement due to dispersion. A claim was made that the Sodium D light at 589 nm is the standard used for measurement. Although this is likely true, I still feel that the wavelength column should be added to the table. The column would force the adder to confirm that measurement was made at the standard wavelength, and if it was not, the material could be specified for an alternative wavelength. The column would also reinforce to the reader the dependence between wavelength and refractive index.Gfutia 23:04, 6 October 2007 (UTC)
thread_title:  Column Additions 

message: The refractive index of materials is dependent on the wavelength used for measurement due to dispersion. A claim was made that the Sodium D light at 589 nm is the standard used for measurement. Although this is likely true, I still feel that the wavelength column should be added to the table. The column would force the adder to confirm that measurement was made at the standard wavelength, and if it was not, the material could be specified for an alternative wavelength. The column would also reinforce to the reader the dependence between wavelength and refractive index.Gfutia 23:04, 6 October 2007 (UTC)
thread_title:  Addition of the wavelength columns 

message: It is not the job of the reader to verify the information source. I think all people on the talk page agree that each item in the table needs to have a verifiable source. Source citation is essential to the credibility of the information. Since each item needs a source, a good way to do this would be to add a reference column to the table.  Also, External links are not references, they are just place for the reader to turn to for additional information. External webpages are fine sources, but just adding it as a link is lazy, a well known referencing standard such as one from IEEE or Harvard referencing should be used. I recommend just going the simple route and using the Wikipedia:Citation templates.Gfutia 23:04, 6 October 2007 (UTC)
thread_title:  Addition of the reference column 

message: I would like to suggest to add an external link to RefractiveIndex.INFO. This website contains dispersion formulas for many materials and has a simple interface for finding a refractive index value for a specified wavelength. Wikipedia's policy does not allow me to add the link myself as I am the author of this site. Please, add a link if you find this site appropriate. Thanks! Mpolyanskiy (talk) 00:32, 1 September 2008 (UTC)
thread_title:  External link suggestion 

message: The refractive index column seems to sort Silicon carbide and diamond the wrong side of each other. - Rod57 (talk) 12:59, 1 December 2020 (UTC)
thread_title:  Table sort sequence error 

message: eg Cinnabar, Sapphire, cubic zirconia. - Rod57 (talk) 13:29, 1 December 2020 (UTC)
thread_title:  Many of the ''Other materials'' should be under ''Solids at room temp''