What you see and what exists
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As you studied in a physics class light is wave and its wave length determines its color. Light with a wave length of about 700 nanometers is red while one with 400 nanometers is violet. Usually light contains many waves of various wave lengths. For example a ray of sunlight contains waves of all wave lengths which human eyes can perceive. In this case we do not feel a specific color and we feel white color. A ray of sunlight can be decomposed by its wave lengths with a prism. Then we can get a spectrum where the color changes continuously from red to violet like a rainbow.
When light contains waves of one wave length (to be precise within a very narrow range of wave length) we feel a color from such light. We call it a pure spectral color. For example we feel yellow from light whose wave length is about 580 nanometers. When we feel a yellow color under the sunlight there must exist a light of about 580 nanometers wave length.
What is interesting here is that even if we feel a yellow color it does not necessarily mean there exists a light of 580 nanometer wave length. When we see a yellow color on a computer display it does not come from a light of 580 nanometer wave length. All Colors on a computer display are made of three primary colors, i.e. red, green, and blue. When we feel a yellow color it is actually a combination of lights of red and green.
We can not distinguish a light of 580 nanometers from a combination of lights of red and green. It is a kind of illusion in our brain. We strongly feel that there exists a yellow color on a computer display and there exist a pure yellow light but it is actually a combination of lights of red and green.
More interestingly, a rainbow does not include a magenta color. This means there is no pure light corresponding to a magenta color. We feel a magenta color only from a combination of lights of red and blue. We feel there is a magenta color and therefore there is a magenta light but in reality there are red and blue lights.
What you see does not always equal what exists.
When light contains waves of one wave length (to be precise within a very narrow range of wave length) we feel a color from such light. We call it a pure spectral color. For example we feel yellow from light whose wave length is about 580 nanometers. When we feel a yellow color under the sunlight there must exist a light of about 580 nanometers wave length.
What is interesting here is that even if we feel a yellow color it does not necessarily mean there exists a light of 580 nanometer wave length. When we see a yellow color on a computer display it does not come from a light of 580 nanometer wave length. All Colors on a computer display are made of three primary colors, i.e. red, green, and blue. When we feel a yellow color it is actually a combination of lights of red and green.
We can not distinguish a light of 580 nanometers from a combination of lights of red and green. It is a kind of illusion in our brain. We strongly feel that there exists a yellow color on a computer display and there exist a pure yellow light but it is actually a combination of lights of red and green.
More interestingly, a rainbow does not include a magenta color. This means there is no pure light corresponding to a magenta color. We feel a magenta color only from a combination of lights of red and blue. We feel there is a magenta color and therefore there is a magenta light but in reality there are red and blue lights.
What you see does not always equal what exists.
As you studied in a physics class, light is wave and its wave length determines its color.
Light with a wavelength of about 700 nanometers is red while one with 400 nanometers is violet.
For example, a ray of sunlight contains all the waves with lengths that the human eye can perceive.
In this case, we do not perceive a specific color. Rather, we perceive a white color.
A ray of sunlight can be deconstructed into its wave lengths with a prism.
Then, we can form a spectrum where the color changes continuously from red to violet like a rainbow.
When light contains waves of one wave length (to be precise within a very narrow range of wave lengths), we perceive color from such light.
For example, we feel yellow from light whose wavelength is about 580 nanometers.
When we perceive a yellow color in sunlight, there must exist a light with a wavelength of about 580 nanometers wave length.
What is interesting here is that even if we feel a yellow color, it does not necessarily mean there exists a light of 580 nanometer wavelength.
When we see a yellow color on a computer display, it does not come from a light with a 580 nanometer wavelength.
All colors on a computer display are made of three primary colors, i.
When we perceive a yellow color, it is actually a combination of lights of red and green.
We can not distinguish a light of 580 nanometers from a combination of lights of red and green.
We strongly feel that there is a yellow color on the computer display and that there is a pure yellow light. But, it is actually a combination of lights of red and green.
We feel a magenta color only from a combination of lights of red and blue.
We feel there is a magenta color and therefore there is a magenta light but, in reality, there are just red and blue lights.
I know the word "perceive" (actually I used it in this entry) but I thought that "perceive" is too technical and I wanted to use a simpler word because people do not think technically when they saw an imaginary color. So I used the word "feel" but you said that it was inappropriate and should be replaced with "perceive".
Are there any words which are simple and suitable for this context? Do you have any suggestions?
"When we observe what looks like yellow light...."
"When we discern the appearance of yellow light..."
"When we detect possible shades of yellow..."
That is the best that I can think of.
I was thinking that the word "perceive" was not used in everyday conversation. Is that right?
As you studied in a physics class, light is a wave and its wavelength determines its color. [correction]
The reason, when mixing paints or markers or things like that you are always taught that the three primary colors are red blue and yellow. Not green. And, that you can't mix yellow. So, I always wondered how you could have yellow or orange colors on a screen.
Mixing red and yellow yields orange. Yellow and blue yields green. And nothing yields yellow.
However, obviously somehow screens do. And, you say it is by mixing red and green.
I wonder if it is because it's projected light rather than reflected light(e.g from paint, fabric, markers, etc.)?
hmmmm....^^
Red, green, and blue are primary colors for additive combination used for projected light.
On the other hand cyan, magenta, and yellow are ones for subtractive combination used for reflected light.
That makes a lot of sense!