WootBot


quality posts: 14 Private Messages WootBot

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Is January a bleak, colorless time of the year where you live? To brighten your gray winter days, we’ve asked Jeopardy! phenom Ken Jennings to poke holes in four of your most embarrassing misconceptions about color. After all, there are plenty of colorful anniversaries to observe this month. The first color TV broadcast was the Rose Bowl of January 1953, and in January 1993, Crayola added sixteen new colors to its crayon boxes, including “Tickle Me Pink” and “Macaroni and Cheese.” The political novel Primary Colors was a January release; so was Radiohead’s album In Rainbows. Could there be a better time of year for a kaleidoscope of facts that—however colorful—are completely wrong?

Color Myth #3: The Deoxygenated Blood in Your Veins Is Blue.

When I was little, I asked my parents once (as I assume most kids do) why the veins in my wrist look blue when the blood inside them is clearly red. I was told, quite straight-facedly, that veins return deoxygenated blood back to the heart and lungs, and deoxygenated blood is actually blue, and not red. This blew my little mind. I asked why I’d never seen blue, deoxygenated blood emerging from any of my various cuts and scrapes, and was told that contact with the air immediately turned blue blood red again. Blue blood was coursing through my body at all times, but I could never see it. I just had to believe in it. It was the circulatory equivalent of the existence of God.

Many children are given this same odd-sounding explanation, which probably comes from anatomical textbook diagrams showing red blood moving away from the heart, and blue blood moving back toward it. But those diagrams are just colored that way for schematic clarity: all blood is red. Deoxygenated blood is a slightly darker red—call it maroon, maybe—but it’s by no means blue. So why do the veins under your skin look blue? It’s not the veins themselves, which are pale and fairly colorless when they’re not filled with blood.

This age-old question was finally answered definitively by a 1996 paper published in the Applied Optics journal, because it turns out that a fairly complicated optical phenomenon is the cause. As red blood vessels get deeper under your skin, their reflectance of red light decreases much faster than their reflectance of blue light, due to the fact that the translucent overlying skin does a very good job at filtering out most of the blue light before it even gets to the vein. If a vein is deep enough (more than half a millimeter), the color that gets bounced back to your eye from its red surface is actually a fairly neutral one, and that neutral color looks bluish to you in comparison to the warmer-colored skin around it. But that explanation is so complex that I’ll probably just tell my kids the same lie I got fed. Think of all the time I’ll save.

Quick Quiz: What veins bring blood from your head back to your heart?

Ken Jennings is the author of Brainiac, Ken Jennings's Trivia Almanac, and Maphead, out now. He's also the proud owner of an underwhelming Bag o' Crap. Follow him at ken-jennings.com or on Twitter as @KenJennings.

 

Woodpecker


quality posts: 15 Private Messages Woodpecker

Jugular?

everclear823


quality posts: 0 Private Messages everclear823

What happened to color myth #2?

kdccrosby


quality posts: 7 Private Messages kdccrosby

I rather liked the idea of being a blue blood.

*sigh* I'll head back to my shack now.

lipophilia


quality posts: 11 Private Messages lipophilia

Actually, crabs and their ilk (e.g. lobsters) have blue blood. Some other critters - mollusks - have green blood.
The reason theirs is differently colored is because they have no hemoglobin. Instead, they have a copper-based oxygen carying protein called hemocyanin. It does change color from oxygenated to deoxygenated, but it is definitely a bright blue color. (Don't go killing a crab to find out - look up hemocyanin images.)

lipophilia


quality posts: 11 Private Messages lipophilia
lipophilia wrote:Actually, crabs and their ilk (e.g. lobsters) have blue blood. ... (Don't go killing a crab to find out - look up hemocyanin images.)



http://www.campbellscience.com/ah.html

radetski


quality posts: 0 Private Messages radetski
everclear823 wrote:What happened to color myth #2?



Yes, I was thinking the exact same thing. Typo? Or perhaps Ken revealed something that "THEY" didn't want us to know and forced Woot to "disappear" it????

SESteve


quality posts: 15 Private Messages SESteve
lipophilia wrote:Actually, crabs and their ilk (e.g. lobsters) have blue blood. Some other critters - mollusks - have green blood.
The reason theirs is differently colored is because they have no hemoglobin. Instead, they have a copper-based oxygen carying protein called hemocyanin.



Which is the same reason that Vulcans have green blood, as we all know.

swankgd


quality posts: 0 Private Messages swankgd

Part 2: http://www.woot.com/Forums/ViewPost.aspx?PostID=4798033

agingdragqueen


quality posts: 125 Private Messages agingdragqueen

Staff

swankgd wrote:Part 2: http://www.woot.com/Forums/ViewPost.aspx?PostID=4798033



Yeah, we mistagged it somehow- but we'll fix it so it appears with the rest of them. Sorry!


s0medude


quality posts: 0 Private Messages s0medude

So... Barely any blue light gets to the blood-filled vein.

If there is such little blue light reaching the vein, why is it seeming to reflect blue light?

Is it really just gray and not even blue?

The part that I hate is: veins seem to reflect blue light; that means that they are actually red -- since if they were truly blue, they would absorb most of the blue light.
(i.e. Red stop signs can't be truly red, or they would absorb all of the red light and appear blue!)

or my view is incorrect. I ain't no physicist.

elezar


quality posts: 4 Private Messages elezar
s0medude wrote:So... Barely any blue light gets to the blood-filled vein.

If there is such little blue light reaching the vein, why is it seeming to reflect blue light?

Is it really just gray and not even blue?

The part that I hate is: veins seem to reflect blue light; that means that they are actually red -- since if they were truly blue, they would absorb most of the blue light.
(i.e. Red stop signs can't be truly red, or they would absorb all of the red light and appear blue!)

or my view is incorrect. I ain't no physicist.



First, you do seem to have a slight misunderstanding on color. In the case of a stop sign, it's considered to be red BECAUSE it reflects the red light, but absorbs the other colors of the spectrum. If it also absorbed the red light, then it would appear black, because it wouldn't be reflecting any color.

However, I do think that Ken's explanation could have been a little more in depth, as I found it a little confusing, too. In general, caucasian skin reflects all colors of light, which is why it appears whitish. However, it's also slightly translucent, so even while some light is being reflected, some keeps penetrating it, until a certain depth when it will reflect all the light. The kicker is that the depth that the light can penetrate is different for the different wavelengths. The reason that not much blue light gets to the veins is because most of the blue light is reflected by the skin above the vein. The veins themselves reflect what red light gets to them. This red light mixes with the blue light reflected from the skin. This combination is actually still more red than blue, but just barely, and as Ken said, it's the unconscious comparison to the skin around it that makes it appear bluish.

BTW, arteries would also appear blue, if any of them were close enough to see through the skin.

MeshColour


quality posts: 2 Private Messages MeshColour

I thought this was the best post for a while, keep it up Ken. The colorblind bulls and rainbow ones seem like fairly common sense to me anyway, for this one the myth was logical enough for me and I didn't worry about it.
And glad the Part 2 thing got sorted out, I was worried this series quit running.


Note: I'm not a physicist either, and mostly going off memory here, so the following is more trying to be a good way to explain it to laymen than be 100% accurate.

s0medude wrote:So...
If there is such little blue light reaching the vein, why is it seeming to reflect blue light?

Is it really just gray and not even blue?


Yeah I think its reflecting gray light, but in comparison with normal skin tone it is blue. So I believe if you had a gray marker and drew on a tan surface it would appear to have a blue tint, if you draw on a light blue surface it would appear to have a red tint.

s0medude wrote:(i.e. Red stop signs can't be truly red, or they would absorb all of the red light and appear blue!)


The definition of a color of an object is the frequency of light it reflects. So yeah the color of something is the colors its surface doesn't absorb.
I'm thinking at the level to measure what color it would 'truly' be, it would be smaller distance than the color wavelengths so is meaningless.

whoiskenjennings


quality posts: 7 Private Messages whoiskenjennings

Guest Blogger

Yeah, I read the full paper from Applied Optics and the way the phenomenon works is so counter-intuitive, you might as well wave your hands as try to summarize it. This was the best I could do in just a paragraph.

My guess is that the "surrounding-pink-makes-gray-veins-look-blue" is a bigger part of the illusion than the complicated skin-refraction mumbo-jumbo anyway.

I was a little annoyed that the paper only covered Cauciasian skin...surely all skin colors are warm enough that the "blue veins" illusion holds for other races too?

Josephus


quality posts: 25 Private Messages Josephus

There are people who live high in the Andes who do look blue all of the time. Their hemoglobin is never saturated because of the small amount of oxygen in the air. The only way that they can get enough oxygen is to have blood that is kind of sludgy- it has a very high hematocrit. Since every hemoglobin molecule has 4 sites that hold oxygen, and there isn't enough oxygen available to saturate the hemoglobin, the body just makes more, so the partially oxygenated hemoglobin is available enough to make up for its lack of saturation.

Deoxygenated hemoglobin is a lot less bright red than oxygenated, so these people who live at extreme altitude end up looking a lot more blue to those who don't, for the same reasons Ken described.

unixrab


quality posts: 10 Private Messages unixrab

So... Mr Jennings I would like to ask a followup question from afacebook comment by Eric S Law:

"So it's the same phenomenon seen by divers as they do deeper... most things look blue because the other colors are blocked/scattered sooner?"

What saith the debunker?

edit: But isn't 'color' what our brain says it is based on context: As in: there's only one color red in this picture: http://www.psy.ritsumei.ac.jp/~akitaoka/redspiral.gif

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Bags of Crap = 3 ------> woot 3.0 is DEAD!!!!
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bsmith1


quality posts: 103 Private Messages bsmith1

What I want to know is, how do we know what I see as red is the same as what you see as red? What if the color I see on a "red" stop sign is actually the color you know as "blue"? Since you can't look through someone else's eyes, there's no way to tell. Right?

elezar


quality posts: 4 Private Messages elezar
unixrab wrote:So... Mr Jennings I would like to ask a followup question from afacebook comment by Eric S Law:

"So it's the same phenomenon seen by divers as they do deeper... most things look blue because the other colors are blocked/scattered sooner?"

What saith the debunker?


Actually, it's sort of the opposite. In the case of veins under the skin, there's actually MORE red light than blue hitting them. However, the light that makes it back to your eyes has a higher ratio of blue:red, than if the vein wasn't in the skin. For divers, since their eyes are also below the point where red light would reach, there's no red light hitting their eyes, so everything appears blue.

unixrab wrote:edit: But isn't 'color' what our brain says it is based on context: As in: there's only one color red in this picture: http://www.psy.ritsumei.ac.jp/~akitaoka/redspiral.gif


Yeah, that's why Ken said "and that neutral color looks bluish to you in comparison to the warmer-colored skin around it"

bsmith1 wrote:What I want to know is, how do we know what I see as red is the same as what you see as red? What if the color I see on a "red" stop sign is actually the color you know as "blue"? Since you can't look through someone else's eyes, there's no way to tell. Right?


That's why definitions for colors are based on wavelengths/frequencies, and not subjective appearance. The way the human eye reacts to various colors is pretty much the same for most people, although obviously slight differences in physiology from one person to another can affect that. Also, like all of our senses, the perception of color is affected at least as much by our brain's input, as the physical input on the eye. So yes, it's quite possible that everyone sees colors a little differently.

satish70


quality posts: 0 Private Messages satish70

Answer to the quiz: superior vena cava?

epobirs


quality posts: 3 Private Messages epobirs

Interesting. The Qualcomm Mirasol technology for reflective color displays, aimed at devices like e-readers, was inspired by butterfly wings that derive their colored appearance in a similar fashion.