# If the color black absorbs all wavelengths, how can I see it? **URL:** \ **Category:** Factual Questions\ **Created:** [February 7, 2004, 6:22am UTC](https://boards.straightdope.com/t/if-the-color-black-absorbs-all-wavelengths-how-can-i-see-it/227955 "2004-02-07T06:22:20Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![Bob55](https://avatars.discourse-cdn.com/v4/letter/b/e9c0ed/32.png) [@Bob55](https://boards.straightdope.com/u/Bob55)\ **Post date:** [February 7, 2004, 6:22am UTC](https://boards.straightdope.com/t/if-the-color-black-absorbs-all-wavelengths-how-can-i-see-it/227955/1 "2004-02-07T06:22:20Z")
As most people know everything we see is due to a reflection of certain wavelengths - something green absorbs everything but reflects green, and something white reflects everything. But what about black? If black absorbs all wavelengths, how can I see something that is black if no light is hitting my eye? I assume most black things I see have hints of other colors embedded, but what if something is perfectly black? Do we only see black objects by their masking of color objects behind them? ---
**Author:** ![RM\_Mentock](https://avatars.discourse-cdn.com/v4/letter/r/e274bd/32.png) [@RM\_Mentock](https://boards.straightdope.com/u/RM_Mentock)\ **Post date:** [February 7, 2004, 6:38am UTC](https://boards.straightdope.com/t/if-the-color-black-absorbs-all-wavelengths-how-can-i-see-it/227955/2 "2004-02-07T06:38:50Z")
> [@Bob55](#): > > Do we only see black objects by their masking of color objects behind them? In the sense of your OP, yes. However, the human brain is very good at filling in the blanks. ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [February 7, 2004, 6:40am UTC](https://boards.straightdope.com/t/if-the-color-black-absorbs-all-wavelengths-how-can-i-see-it/227955/3 "2004-02-07T06:40:09Z")
You see black things because black is the absence of light. Your brain knows that the absence of light means black. ---
**Author:** ![Bob55](https://avatars.discourse-cdn.com/v4/letter/b/e9c0ed/32.png) [@Bob55](https://boards.straightdope.com/u/Bob55)\ **Post date:** [February 7, 2004, 6:54am UTC](https://boards.straightdope.com/t/if-the-color-black-absorbs-all-wavelengths-how-can-i-see-it/227955/4 "2004-02-07T06:54:27Z")
> [@friedo](#): > > You see black things because black is the absence of light. Your brain knows that the absence of light means black. Interesting, it almost makes me question the reality of what I see when I think about it like that. My brain can determine the color and distance of any object by the wavelengths it emits, but in the absence of this data it “fills in the blanks”. ---
**Author:** ![John\_Kentzel-Griffin](https://avatars.discourse-cdn.com/v4/letter/j/ccd318/32.png) [@John\_Kentzel-Griffin](https://boards.straightdope.com/u/John_Kentzel-Griffin)\ **Post date:** [February 7, 2004, 6:55am UTC](https://boards.straightdope.com/t/if-the-color-black-absorbs-all-wavelengths-how-can-i-see-it/227955/5 "2004-02-07T06:55:08Z")
You see black things because nothing is perfectly black. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [February 7, 2004, 8:05am UTC](https://boards.straightdope.com/t/if-the-color-black-absorbs-all-wavelengths-how-can-i-see-it/227955/6 "2004-02-07T08:05:10Z")
> [@DrMatrix](#): > > You see black things because nothing is perfectly black. Excpet a Black Hole, of course. But then, we can’t actually see them, so you are right! ---
**Author:** ![Charlie\_Tan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/charlie_tan/32/12582_2.png) [@Charlie\_Tan](https://boards.straightdope.com/u/Charlie_Tan)\ **Post date:** [February 7, 2004, 8:35am UTC](https://boards.straightdope.com/t/if-the-color-black-absorbs-all-wavelengths-how-can-i-see-it/227955/7 "2004-02-07T08:35:35Z")
> [@Bob55](#): > > Interesting, it almost makes me question the reality of what I see when I think about it like that. My brain can determine the color and distance of any object by the wavelengths it emits, but in the absence of this data it “fills in the blanks”. Oh yes. You have a blind spot on the retina, where the visual nerve is attached. That blind spot is roughly the equivalent of 150 full moons in area. May I suggest [this book](http://www.amazon.com/exec/obidos/tg/detail/-/0521571553/qid=1076142729//ref=sr_8_xs_ap_i1_xgl14/104-7519831-5431110?v=glance&s=books&n=507846) which explains these things in depth. In short - your brain has a mind of its own. ---
**Author:** ![Achernar](https://avatars.discourse-cdn.com/v4/letter/a/e274bd/32.png) [@Achernar](https://boards.straightdope.com/u/Achernar)\ **Post date:** [February 7, 2004, 9:06am UTC](https://boards.straightdope.com/t/if-the-color-black-absorbs-all-wavelengths-how-can-i-see-it/227955/8 "2004-02-07T09:06:21Z")
> [@John Mace](#): > > Excpet a Black Hole, of course. But then, we can’t actually see them, so you are right! That’s only because the thing about space, your basic space color, the color of space, is black. What if a black hole were in front of an emission nebula or a companion star or a huge pink modern art sculpture. Wouldn’t we “see” it as a black object then? ---
**Author:** ![GuanoLad](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/guanolad/32/42_2.png) [@GuanoLad](https://boards.straightdope.com/u/GuanoLad)\ **Post date:** [February 7, 2004, 10:44am UTC](https://boards.straightdope.com/t/if-the-color-black-absorbs-all-wavelengths-how-can-i-see-it/227955/9 "2004-02-07T10:44:45Z")
It isn’t an absence of object - it’s an absence of colour. The thing is still there, but instead of red or green or puce or magenta, it’s no colour; that is - black. ---
**Author:** ![RM\_Mentock](https://avatars.discourse-cdn.com/v4/letter/r/e274bd/32.png) [@RM\_Mentock](https://boards.straightdope.com/u/RM_Mentock)\ **Post date:** [February 7, 2004, 3:26pm UTC](https://boards.straightdope.com/t/if-the-color-black-absorbs-all-wavelengths-how-can-i-see-it/227955/10 "2004-02-07T15:26:33Z")
> [@The Gaspode](#): > > Oh yes. You have a blind spot on the retina, where the visual nerve is attached. That blind spot is roughly the equivalent of 150 full moons in area. The blind spot and how the brain treats it is what I was thinking of when I said it is good at filling in the blanks. Is it really that large? The full moon is about 3/8 inch at arm’s length, so 150 of them would be 12 times that, or 4 1/2 inches in diameter, at arm’s length. That’s not been my experience. ---
**Author:** ![Futile\_Gesture](https://avatars.discourse-cdn.com/v4/letter/f/f05b48/32.png) [@Futile\_Gesture](https://boards.straightdope.com/u/Futile_Gesture)\ **Post date:** [February 7, 2004, 3:34pm UTC](https://boards.straightdope.com/t/if-the-color-black-absorbs-all-wavelengths-how-can-i-see-it/227955/11 "2004-02-07T15:34:16Z")
All matter reflects light to one degree or another. [But here’s the blackest black so far.](http://news.bbc.co.uk/1/hi/sci/tech/2732487.stm) ---
**Author:** ![Uncivil](https://avatars.discourse-cdn.com/v4/letter/u/ccd318/32.png) [@Uncivil](https://boards.straightdope.com/u/Uncivil)\ **Post date:** [February 7, 2004, 3:37pm UTC](https://boards.straightdope.com/t/if-the-color-black-absorbs-all-wavelengths-how-can-i-see-it/227955/12 "2004-02-07T15:37:48Z")
> [@Bob55](#): > > As most people know everything we see is due to a reflection of certain wavelengths - something green absorbs everything but reflects green, and something white reflects everything. But what about black? If black absorbs all wavelengths, how can I see something that is black if no light is hitting my eye? I assume most black things I see have hints of other colors embedded, but what if something is perfectly black? Do we only see black objects by their masking of color objects behind them? When you look at a black object, it reflects only a very small amount of light, not no light at all. This stimulates only a small number of nerves in your eye, and your brain interprets this as blackness. Only black holes and completely empty space are truely black (reflect no light). But the human eye can’t detect light levels below a certain level, so we percieve many things as being black in colour. ---
**Author:** ![mnemosyne](https://avatars.discourse-cdn.com/v4/letter/m/c4cdca/32.png) [@mnemosyne](https://boards.straightdope.com/u/mnemosyne)\ **Post date:** [February 7, 2004, 7:27pm UTC](https://boards.straightdope.com/t/if-the-color-black-absorbs-all-wavelengths-how-can-i-see-it/227955/13 "2004-02-07T19:27:27Z")
A slight hijack, but relevant to the idea of the brain “filling in the blanks”: Ever notice how you can tell what colour something is, even in dim or tinted lighting (assuming the tint isn’t overwhelming). I’m thinking along the lines of the yellowishness of a halogen light versus the bluishness of fluorescent lighting. If you were to take a picture of a person wearing a white t-shirt, then isolate the colour, it wouldn’t look at all whte, but under those lighting conditions, your brain selects the object that is MOST white, defines it as “white”, and all your other colour determinations are done relative to it. I don’t know that I could find a cite for this - the was the result of a class discussion last year, so I don’t really know what the research out there states, but I thought it was pretty neat nonetheless. Your brain does amazing things in order to make sense of the world! ---
**Author:** ![Charlie\_Tan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/charlie_tan/32/12582_2.png) [@Charlie\_Tan](https://boards.straightdope.com/u/Charlie_Tan)\ **Post date:** [February 7, 2004, 10:05pm UTC](https://boards.straightdope.com/t/if-the-color-black-absorbs-all-wavelengths-how-can-i-see-it/227955/14 "2004-02-07T22:05:33Z")
> [@RM Mentock](#): > > Is it really that large? The full moon is about 3/8 inch at arm’s length, so 150 of them would be 12 times that, or 4 1/2 inches in diameter, at arm’s length. That’s not been my experience. I can only go by what I read in that book (which is fascinating, BTW), but the authors make the argument that our brains fool us in believing that we see things, that we can’t see. > [@](#): > > Our colour sense derives from three different types of light-sensing organs known as cones, which responds selectively to light in different ranges of frequencies (roughly red, green, and blue). However, it would be taking far too literal a view to describe our colour sense as a frequency detector. It does not analyse incoming light, “read off” its frequency, and consult a look up table to determine that it is red. What happens is rather the other way around: light of that frequency affects the ‘red’ connes more strongly, than the other two types, and our brain is set up so that it then ‘sees’ red. \ > While the eye may be like a camera in many respects, its essence is quite different. Without a brain to interpret its signal, there are no pictures. In fact, an animal’s eye-brain system has to be fine tuned during development before the animal can see properly. Experiments have shown that unless kittens are exposed to horizontal lines att the appropriate stage of early development, they grow up into adults that can never ‘see’ horizontal lines. This tells us that the eye can be picking up the input signals, but the eye-brain system may not know how to interpet them: it cannot drape the appropriate figments over its perceptions of reality, because it never got the appropriate training. (pp. 139-140) I know this doesn’t say anything about that figure of 150, but I couldn’t find it right away and I hope the passage above shows that the things that we see are not the things that really are, but rather an interpratation, suitable for our needs. ---
**Author:** ![RM\_Mentock](https://avatars.discourse-cdn.com/v4/letter/r/e274bd/32.png) [@RM\_Mentock](https://boards.straightdope.com/u/RM_Mentock)\ **Post date:** [February 8, 2004, 11:57am UTC](https://boards.straightdope.com/t/if-the-color-black-absorbs-all-wavelengths-how-can-i-see-it/227955/15 "2004-02-08T11:57:00Z")
> [@The Gaspode](#): > > I can only go by what I read in that book (which is fascinating, BTW), but the authors make the argument that our brains fool us in believing that we see things, that we can’t see. Only? 🙂 You have one other option, at least! Or, I’d guess, two…