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> This is a hard question to answer. [...] Oh, nice - I'd forgotten how the brief version of the question sends conversations in unexpected directions, and tur

> This is a hard question to answer. [...] Oh, nice - I'd forgotten how the brief version of the question sends conversations in unexpected directions, and turns up a wide variety of conceptions. Long ago, to narrow the diversity of responses, I switched to asking longer versions, like "A 5-year old asks you: 'I'm told the Sun is a big hot ball! Awesome, I love balls! What color is the ball?' What color is the Sun?" Which has gotten a bit boring - same old failure modes grown familiar. Diverse could be useful again, for thinking about teaching color, and more fun. > “intense pain followed by blindness”. :-) Sooo... one can't tell what color a light is, unless you can look at it directly...? :P > sunlight is “white”, because it excites all of our cone cells So does my red shirt, no? Necessary but not sufficient. I'd love to find some content which tells a K-6 accessible story of spectra being convolved with L/M/S response curves. Related common misconceptions from textbooks include "white means a mix of all colors" or "all colors equally". > remain “white”, because our visual system adapts. IIRC, the range of colors for which you can't tell there's a tint, rather than merely ignoring it, isn't very large. You get used to 5000K incandescent, but can still tell it's "warm" (ie, cooler/redder than white). Hmm, I suppose that's an increasingly less-than-wonderfully-accessible exemplar... maybe tablet/display night mode? > diffraction grating glasses Nifty. I wonder how they might be tweaked to be better for education. Maybe increase clarity, by using a strip of one-axis grating, cutting across a neutral-density filter background - so you still get the bright spectra, but can more easily switch between seeing source and spectra. Maybe bend the grating to spread the spectra out more?? Thanks!

jacobolus 5y ago
> So does my red shirt, no? No, the light reflected by your red shirt is not like the light from the sun, because it is nowhere near the brightest object in view. But you are right that if you made a lamp with the same spectral power distribution as light reflected by your red shirt but several orders of magnitude brighter, it would still probably be outside the range considered “white”, even after adaptation. > how they might be tweaked to be better for education. I think the current disposable cardboard ones which cost like 50¢ each (maybe less?) when bought in bulk are pretty good for education. If you walk around at night with diffraction grating glasses looking at different kinds of lamps, you can learn a lot about what kind of light they produce.

jacobolus 5y ago

> So does my red shirt, no? No, the light reflected by your red shirt is not like the light from the sun, because it is nowhere near the brightest object in view. But you are right that if you made a lamp with the same spectral power distribution as light reflected by your red shirt but several orders of magnitude brighter, it would still probably be outside the range considered “white”, even after adaptation. > how they might be tweaked to be better for education. I think the current disposable cardboard ones which cost like 50¢ each (maybe less?) when bought in bulk are pretty good for education. If you walk around at night with diffraction grating glasses looking at different kinds of lamps, you can learn a lot about what kind of light they produce.