IlyaShpitser comments on A Fable of Science and Politics - Less Wrong

113 Post author: Eliezer_Yudkowsky 23 December 2006 04:50AM

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Comment author: Qiaochu_Yuan 05 January 2013 10:00:51AM 9 points [-]

No. No, no, no, no. Blue light is light that has a wavelength of approximately 450-495 mm and green light is light that has a wavelength of approximately 520-570 mm. If I had a device that measured the wavelength of light, the wavelength of the light coming from the sky is an empirical fact. It may not be constant, and if the wavelength is in between those ranges then it may look more bluish-green or greenish-blue depending on various factors, but I cannot socially construct the wavelength of light emitted by a given source.

What do you think this is a metaphor for?

Comment author: IlyaShpitser 05 January 2013 10:30:41AM *  3 points [-]

No, blue is what's perceived as blue. There are problems with physical definitions because of an endless list of exceptions involving perceptual disorders, optical illusions, lighting conditions, etc. etc. etc. People worked on this problem, and there is no objective definition of color that I am aware of.

Comment author: BlueAjah 12 January 2013 01:31:48PM 8 points [-]

No, blue is what is collectively perceived as blue, while also not being collectively perceived as any other colour (or color if you are a "gray"). That's how they came up with the objective, standard, scientific definition of blue above.

And the sky isn't pure blue, it's a quarter of the way between blue and green.

Comment author: Alicorn 12 January 2013 07:41:39PM 4 points [-]

colour (or color if you are a "gray")

This is a charming phrase.

Comment author: [deleted] 12 January 2013 04:33:02PM 0 points [-]

No, blue is what's perceived as blue.

Was Neptune not blue in 1400 because nobody had perceived it yet?

Comment author: deathpigeon 12 January 2013 05:34:51PM 1 point [-]

It was blue because its color was within the set of colors that were commonly perceived as blue. It's the color that is defined by human perception, not each individual instance of said color.