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Brain Dump…

October 2, 2012

Some Common Ideas I Hear and Some Evidence to Support Them

When you shine “white” light on non-reflective colored surfaces, the light that comes off carries or takes on the color of those surfaces. That colored light goes off in many directions (not just one).

When a flashlight was aimed at a colored piece of construction paper, pieces of white paper and even our hands that were nearby would be illuminated with colored light”

Colors from objects outside get inside box theatre to not only form an image, but a colored image that matches the color of the objects.

The color that objects appear to be in sunlight (or artificial light engineered to be similar to sunlight) is what we typically call “the color of an object”. The perceived color of an object can vary from its “natural” color if the light is colored light.

When we shined red light on the rainbow fabric, we saw a dark band and a red band. In white light, what was the dark band was now green, blue, and purple. What was the red band was now red, yellow, and orange.

When we shined red light on the yellow jacket and the white wall, the perceived color was indistinguishable.

Sunlight seems to consist of many different colored light (ROYGBV), and artificial light made to be similar to light is made of many different colored light as well.

When sunlight passes through a prism, the colors can be seen separately

When sunlight shines on a CD, the color can be seen separately

When sunlight passes through water the right way, it can creates a rainbow that shows the colors separately

When an i-phone screen is examined under a microscope, white light is made up of tiny reds, greens, and blues.

Questions I’ve heard come up

Does light absorb color from surfaces, or is light absorbed by colored surfaces?

What is the ontology of color? Is color a property of objects, a property of light, or both? Or is color just a physiological / psychological response to light entering our eye and our brain interpreting it?

Is the color of an object determined by the colors that reflect off it, or determined by the colors that are absorbed into it?

Is black all of the colors or the absence of colors? Is white all of the colors or the absence of colors?

If surfaces absorb some colors and reflect others, how does the object “know” which ones to reflect and which ones to absorb? What’s the mechanism?

How is mixing paint and mixing light similar / different?

Is every image (including color images) made of up tiny glowing dots /pixels, even if they are too tiny for us to see?

What is grey? What is brown? (If the color of an object really is the rainbow colors that are not absorbed, how can these be made since gray and brown aren’t in the rainbow?)

In what ways are sunlight and artificial light similar / different?

Why is yellow on the computer screen made up of green and red dots?

How does our eye perceive color? What is color-blindness? What does world look like to color blind people?

How do animals have night vision? Can they see in pitch dark, or just see well even in really dim light? How does night vision technology work?

What are primary colors? Why doesn’t a computer use red, yellow, and blue?

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2 Comments leave one →
  1. ljatkins permalink
    October 2, 2012 3:12 pm

    Curious about this list — is it just yours, to keep ideas straight? Is it public?– do you students also have a sense of “these are the ideas about color and the observations that support them?” – I’ve been a little disappointed in the recent homework and work in class – there seems to be a sense that we all have our ideas and opinions (which aren’t reconciled) – and I’m thinking up ways to work on that.

    However, I do think many (most?) of my class could answer the questions you posed– I might share them with my class and see what they think.

    • October 2, 2012 3:46 pm

      This is just me processing class. One day we explicitly write up: what arguments/evidence support or refute each of our theories. And much of what I’ve written comes from that, and yesterday’s conversation about what happened when red light shined on fabric with all rainbow colors. Something like this needs to be public—whether from students or me giving a “state of union” address.

      Right now, we are certainly not in a place of anyone can have their opinion. Yesterday got a bit heated about the nature of color. A lot of it about ontology, so introduced the word.

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