Talk:Spectrum

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A conjecture: Is it because dispersed light that had passed through a prism looked ghostly that the word spectrum was introduced into the physical sciences? Michael Hardy 00:05, 18 Aug 2004 (UTC)

Page move[edit]

This is a very large dis-ambiguation page. Can anyone move this page to Spectrum (disambiguation) and Optical spectrum here?? 66.245.84.65 23:28, 16 Oct 2004 (UTC)

I don't think optical spectrum should be moved here. The optical spectrum is only the spectrum of visible light. The word spectrum is used far more generally than that even if one restrict discussion to electromagnetic waves. X-rays and radio waves also belong to the electromagnetic spectrum. Michael Hardy 00:09, 17 Oct 2004 (UTC)

Reverse page move[edit]

This page used to contain a nice article on the general concept of the spectrum. Someone seems to have overwritten that article by doing a copy-paste move of the former Spectrum (disambiguation) to this page. I propose to reverse have reversed this non-consensual copy/paste move and restored the original article. Comments?--Srleffler 20:17, 28 February 2007 (UTC)

TV industry[edit]

I was looking for Spectrum as used in the TV industry, "Following a simulcast period, analogue services are expected to be switched off around 2015. This will allow spectrum to be made available for new services on the DTT platform. HDTV is not expected to begin prior to analogue switch-off." I wanted to know if Specturm refers just to cable, or to Satellite at well. -C 16 Jan 2009 —Preceding unsigned comment added by 85.69.13.141 (talk) 10:30, 16 January 2009 (UTC)

You probably want Frequency allocation or Spectrum management, or perhaps Radio frequency if you're interested in the underlying physics.--Srleffler (talk) 13:19, 16 January 2009 (UTC)

Goethe and Schopenhauer[edit]

I have a couple concerns about the following text in the "Origins" section:

The word "spectrum" [Spektrum] was strictly used to designate a ghostly optical afterimage by Goethe in his Theory of Colors and Schopenhauer in On Vision and Colors.

First, the sentence is not really about the origins of the term, but rather is an example of a relatively late use of the term to mean "afterimage" rather than its more conventional meaning. Second, I don't believe either Goethe or Schopenhauer used the English word "spectrum", since both were writing in German. The sentence, as written, seems off-topic for this article, which is about "spectrum" in the sense of "a condition that is not limited to a specific set of values but can vary infinitely within a continuum." It could perhaps be mentioned in the next section as an example of a contrary use of the term, but at the least a citation is needed to a secondary source that discusses Goethe and Schopenhauer's odd usage and puts it in context. (Was this usage common among scientists at the time? Among artists? In English? In German? Is it totally unique to Goethe and Schopenhauer?)

The fact that the authors and their translators use "spektrum"/"spectrum" in an unusual way should definitely be noted in the article Theory of Colors. I notice the article itself seems to use the word in its modern sense.--Srleffler (talk) 06:29, 26 February 2010 (UTC)

Goethe's and Schopenhauer's use of the word "Spektrum" [spectrum] is more appropriate than Newton's use. An afterimage is ghostly. It is an appearance in which there is no material basis. Newton's band or series of colors is not ghostly in any way. Why is Newton's use of the word thoughtlessly assumed in the article as being correct?Lestrade (talk) 01:26, 25 October 2012 (UTC)Lestrade

Error in image?[edit]

There seems to be an error in image titled "The spectrum of a uniform light source rendered into the sRGB color space." (File:Rendered Spectrum.png)

If the numbers below the rendered rainbow colors stand for frequencies, then they are in the wrong order. Isn't red supposedly lower in frequency than ultraviolet?

Sirkkalap (talk) 15:39, 23 November 2013 (UTC)

The numbers are wavelength, measured in nanometers. Wavelength is inversely proportional to frequency, so red has longer wavelength than violet.--Srleffler (talk) 15:51, 23 November 2013 (UTC)