Re: Color

[Jim Green <JMGreen@SISNA.COM>]

Ah, Michael, you give evidence to give wonder to my point exactly.

You show "white" light through a monochrome purple filter.  You say dear
beloved wife let us agree to call this color "purple."   She says ok.  You
now project the white light beam through a prism.  You say see the "purple"
on the spectrum - it looks bluish like the adjacent blue on the
spectrum.  She says no it looks more reddish like the red on the other end
of the spectrum.  She does not perceive the purple the same as you do.

You have demonstrated that your wife sees the same wavelengths as you do
but not that she has the same visual experience that you do.   She sees
what you call cyan as bluish and you see it as greenish.  Or maybe she is
just a woman.

Larry says Good Grief, the physiology, biology, chemistry, and physics of
humans is not all that different from individual to individual -- at least
on the average --  thus we all must have the same visual experience -- we
can argue about language but we see the same thing.

I am still wondering.

Jim Green

> I have an ongoing argument with my wife about the color blue.  She wants to
> call cyan blue.  The color I call blue she wants to call violet.  I can take
> a cyan filter, run the light through a diffraction grating, and show her
> beyond doubt that there is just as much green in the light as there is blue.
> She agrees.  When we look at the projection screen she sees the band of
> color start the same place I do and end the same place I do.  See agrees the
> green part looks the same brightness or even a bit brighter than the "blue"
> part.  I show her another filter (I call blue) and run it through the
> diffraction grating and she admits it looks the same as the cyan filter with
> the green removed.  Have I made my point?  No, she still says the cyan is
> what she calls blue and my "blue" is what she calls violet.
>
> I am totally convinced we see the same thing.  We just describe it
> differently.
>
> Related topic.  John Denker is certainly correct that brightness is
> important.  That is why so many astronomy students are disappointed when
> they look through the telescope and see Orion's Nebula in black-and-white
> when they were expecting to see it in color.  All the pictures they've seen
> of neat astronomical objects are in color.  Why doesn't it really look that
> way?  Too dim for the eye to perceive the color... that's why.
>
> Also when I have talked about star colors with students, and have examined
> stars both with naked eyes and with telescopes, they often disagree on
> whether it is red or orange or yellow.  I assume this is partly a brightness
> issue, but also partly the "descriptive issue" I've described above.  I
> personally don't describe Betelgeuse as a red star, I think it is more
> orange than red.  Some students don't even think it is orange, and they call
> it yellow.  I have indeed observed some carbon stars with the telescope that
> I would definitely describe as red.  Some of my students don't even see
> these at all.  For the real faint stuff they don't have the patience and
> they also have a hard time trying to look at things through the telescope
> with peripheral vision rather than direct view.  Peripheral vision is often
> better at picking out faint stuff.  That's another reason people might
> disagree about what they see.  When I am looking in an eyepiece of a
> telescope I try to use both direct and peripheral vision (back and forth) to
> see everything I can see.  It took me a while to train myself to do that.
>
>
> Michael D. Edmiston, Ph.D.              Phone/voice-mail:       419-358-3270
> Professor of Chemistry & Physics        FAX:                    419-358-3323
> Chairman, Science
> Department            E-Mail                  edmiston@bluffton.edu
> Bluffton College
> 280 West College Avenue
> Bluffton, OH 45817


Jim Green
mailto:JMGreen@sisna.com
http://users.sisna.com/jmgreen