this post was submitted on 29 May 2025
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I read this once before and it's one of those facts I find endlessly fascinating. It's simple and obvious why it wasn't normal before recent times...
It just scratches my nerd fact itch I guess.
It's right up there with
And
Oh and
-we see the color that is not absorbed by an object. So essentially we see every color the object ISNT.
Not to be too pedantic but that last one isn't quite correct. Color "happens" after the object is hit with light - it's defined by our perception of the wavelengths that bounce off.
Which I suppose raises the question... Is a blue box still blue in total darkness? Is its color defined by the light its reflecting or it's capacity to reflect? I think the latter but I don't really know
Plants are green, so which colors are used by the plant for photosynthesis?
Depends on the context of the question, but generally I'd argue it is still a blue box, since that's most likely a question about the property of the box, rather than its current state.
Technically it is an emergent property of the system composed of the light source, the box and our eyes.
Please be pedantic. I enjoy it. That isn't sarcasm, I love a good "technically...."
Yes you're right. It is fun to think about tho.
Well color requires light in the visible spectrum. So, imo, no in a pitch black room the box would not be blue
But if you took a box you know is blue into the pitch black room, nothing changes about the box. Would it not still have the same characteristics that cause us to perceive it as blue?
Likewise, is it still blue if you close your eyes?
The thing is, the box isn't blue, it just reflects blue light wavelengths much more than others.
When we say "the box is blue" we are either technically incorrect or we're using it as a shortcut for "the box reflects mainly blue light wavelengths".
In a dark room, that box will not reflect anything, so if our "the box is COLOR" is really just the shortcut for saying that the box mainly reflects that color, then it would make sense to say "the box is black" if you mean what it is reflecting at that moment or "the box is blue" if you mean its capability when it comes to reflecting colors.
It still retains the pigments which will reflect blue. We call pigments by the names of their colors even when they're in closed boxes in the dark, because we know their properties relative to white light.
I agree that when we say something IS a color, we mean "it reflects certain wavelengths" but I disagree with the conclusion.
Let's say you have a red box and a blue box. You put a brick in the blue box then put both boxes in the dark closet. Someone asks you the color of the box with the brick. What do you tell them?
If it makes sense that the blue box is no longer blue in the dark, we'd ask "what color will the box be when I open the door?"
Therefore, I'd argue that the color of an object is defined by it's capacity to reflect/emit light. After all, is a farmer not a farmer while they sleep?
As your own example illustrates, it boils down to whether one is talking about the present status of the box or the capabilities of the box.
In your example, the capabilities of the box are what maters because the other person can bring it to be under different lighting conditions were those capabilities are fully used. If however we're talking about boxes bolted to the floor of a dark room which cannot be lit, for all practical effects and purposes and as far as people know both boxes are black, which is why in such a situation the advice given to find the box would not at all be color but rather thing like shape and size.
That said, after thinking it some more, I think people do say "the OBJECT is COLOR" only when they're talking about color reflective capabilities and use "the OBJECT looks COLOR" specifically for the current status of reflecting color, even if sometimes they confuse status and capability and might say that something "is" COLOR having seen it only under lighting conditions which are not good enough to fully judge that object's color reflection capabilities and strictly speaking should have used "looks" instead (I only mention this because when it happens it can cause funny confusions if the person they're talking to actually saw that object under different lighting conditions and thus thinks of it as having a different color).
I feel like if someone locked in a dark room with a blue box was asked what color it was, they'd say "I don't know" as opposed to "black"
Interesting point about is vs looks. I was thinking about LEDs before (hence the "reflect/emit" part) but I think I want to walk that back a little...if an LED only emits blue light, we'd say the LED is blue. But an RGB LED? It definitely depends on what it's currently doing. In both cases, the reflective properties of the LED module while it's off are the same. So it's like there's a hierarchy to how we define color...color it's emitting > color it CAN emit > color it CAN reflect > color it's reflecting.
I'm just riffing here so I don't really have a conclusion for that but it's intersting to think about. There's probably other examples that go against my hierarchy idea.
Well the characteristics that cause us to perceive it as blue comes from the light reflecting off of it's surface. So without the light that characteristic goes away. But if you close your eyes (and stay in a lit room) I would say it's still blue, trees falling in the woods and all that.
I don't think "color" is an immutable property of an object
Well, technically your eyes (and the wavelengths they can perceive) are part of the system of light source, box and your eyes that make it blue. If the light source emitted a different spectrum of light the box would reflect other wave lengths, if the box was different it would and if our eyes perceived a different spectrum of light it would also likely be split up into named parts differently.
Your last point is more of a philosophical / semantical one. What does it even mean that something is a specific color?
It's like how blue butterflies actually don't have any blue pigments but rather have a nanostructure that interferes with light in a way that favors blue.
https://www.youtube.com/watch?v=29Ts7CsJDpg
Definitely philosophical! I don't think there's really a definite answer
Yes you're right. It's just something I like to think about.
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Relevant XKCD.