Satellite composite image of Western Hemisphere from NASA

Satellite composite image of Western Hemisphere from NASA

Ooh ooh ooh, Bad Astronomy posted (a while ago) a fabulous list of Ten Things You Didn’t Know about the Earth. If you dig my science myths, check this one out. Such gems as “The earth is smoother than a billiard ball,” “Destroying the earth is hard,” and “Mt. Everest isn’t the biggest mountain.”

See also his earlier Ten Things You Didn’t Know about the Milky Way.

Kyle Flood from Victoria, British Columbia, Canada Hey all,

I just posted a new episode to my Science Teaching Tips podcast… a bunch of fun activities having to do with taste, and debunking some common myths about taste. Check it out — Episode 41. It’s a matter of taste.
This activity is from the Exploratorium’s Human Body Explorations:

The Nose Knows activity:

More activities by Karen Kalumuck:

Image from Kyle Flood from Victoria, British Columbia, Canada

I saw this on a teachers’ listserv, and realized that I had been told the same myth as a child, and it was one of those many things that worms its way into your knowledge base and then you never question it again. It’s funny how this happens, because with any thought, you often realize that these don’t make sense (like the idea that polar bear fur is fiber optic, which just doesn’t stand up to scrutiny). There is a delightful episode of This American Life called “A little bit of knowledge” (and when that can be a dangerous thing). One of the stories is about a woman who believed until very late in life that unicorns actually exist. She wasn’t naive or stupid, it was just one of those beliefs that never got questioned, but when confronted with defending the idea, she realized that it was ludicrous. Anyone else got any weird things like this that have cropped up?

So, here’s the myth that was stuck in my brain since I was a kid: Blood in our veins is blue! Here’s the question the teacher posed.

Can someone please clarify for me why blood is blue–or red? What
are the current misconceptions as well as understanding? I would appreciate any
insights or updates. Thanks so much!

Another teacher agrees:

Many of my students–amd adults–categorically state that blood is
really blue. After my years of training as a health care
professional and many biology and physiology courses, the only
‘blue blood’ I’d heard about, were tales recounted by long-
deceased family relatives, waxing nostagically about their royal,
geneological, family tree.

I know that for me, the explanation was that after blood left the heart, it was deoxygenated, and thus blue. That’s why the veins in my wrists look blue. But the arteries were red. Here’s the real story from the Exploratorium’s physicist:

Flesh proteins scatter light, like the sky they scatter slightly more
blue than red light.

The slight blue is lightly pastel when seen against white flesh,
however against a dark background it is a clearer blue. Thus against
the dark background of an artery or vein the skin between the artery
and the surface will be seen to be blue.

This is similar to a blue feather. A feather is blue not because of
pigment but because the physical structure of the feather scatters
blue light. The back of the feather is black with melanin so the blue
scattered light stands out against the dark background. Bleach will
destroy the melanin but not the blue scattering structure. So by
bleaching the feather it still scatters blue but without the black
background the feather looks white. Paint the back of the feather
black again and once again it appears blue.

This same effect gives some pasty faced men with black beard hair the
look of blue skin. The dark hair follicles beneath the skin provide a
dark background against which the blue scattering of the skin can be

So once again understanding perception is important to
science…someone has got to point this out to the California State
Science Standards people.

Paul D

Of course, the text books are helping this misconception stay alive by continuing to illustrate veins
as blue and arteries as red!

So, one enterprising teacher tried a neat experiment:

Hi Paul,

Based on your answer here I tried something really cool. You said red light penetrates skin the deepest, so that is the white light color we see best through the finger tip. That lead me to try the following: I replaced the white light from the mini-mag light with a red laser pointer and then a green laser pointer. The red shone through, but not the green. Very cool!! The green laser is even slightly higher wattage, so it would have the advantage that way. I have no blue laser, but am assuming it wouldn’t make it through the finger tip either.

One final question based on your response:

Bones of the finger are translucent?? I thought they were opaque. Are finger bones much different from other bones (thinner or less dense??). X-rays penetrate tissue effectively, but mostly bounce off bones, right?? It seems strange that finger bones would be better transmitters of visible light than x-rays.

Thank you!

And the physicists’s reply:

Bone absorbs x-rays more or less depending on the density of the bone, so we can see bone structure in x-rays.

Bones are white in the visible. They scatter white light.
But they don’t absorb it much. So the light comes into the bone and goes out in a random direction. So while you cannot see through a bone, it does not block the passage of all white light. Bones are translucent not opaque. (Small thin bones allow more light through than larger bones.

Neat stuff!

Laurie Grace

This myth appears in a bunch of textbooks, so it’s not surprising that it’s persisted. The myth is that we mostly taste sweetness, bitterness, saltiness, and sourness at different areas of the tongue. While it’s true that we do have different taste sensations on different areas of the tongue, the exact distribution of sensitivity depends on the particular person doing the tasting. Try this out with a few friends — make your own taste maps and see if they coincide or not. The original myth stems back to the early 1900’s when a German reseacher named Hanig published data on taste sensitivity of different areas of the tongue. The differences in sensitivity he reported were real — but they were so slight as to be of no practical significance. Nobody bothered to check or refute it until many years later, when the idea was already firmly rooted in our popular consciousness, and textbooks.

Some other interesting tidbits about taste:

– These four basic “tastes” have been expanded to five. The fifth is called “umami” which loosely translates from Japanese to “deliciousness.” It’s the flavor of amino acides (such as meat broth, aged cheese, or glutamate, as in monosodium glutamate, or MSG; ) which explains why things with MSG taste so good. There’s also some debate about a sixth receptor for fat.

– Your nose plays a huge role in what you taste. If you plug your nose it can be difficult to tell the difference between a potato and an apple. That’s why things taste bland when you have a cold and your nose is stuffed up.

– Taste buds are clusters of taste receptors. The taste buds themselves are too small to see, but they live on the end of little protrusions of tissue called papillae. You can see your papillae easily by dropping a few drops of food coloring on your tongue (blue works best). The pale dots are the papillae. Taste receptors are activated when chemicals in food bind to them, the taste receptor then fires and sends a message to your brain. Within a few seconds the taste receptor adapts to the flavor and fires much less strongly.

– Your taste sensations depend on the temperature of your tongue! That’s why Ben & Jerry’s serves its ice cream slightly warm in its tasting room, to enhance its sweetness.

For more information, see:

Bartoshuk, L. M. 1993. The biological basis of food perception and acceptance. Food Qual. Pref. 4:21-32

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Gosh, I’d like to believe this one, it’s just such a “cool” idea. One argument against this idea is that if you take thousands of pictures of snowflakes, it’s still not a very good statistical sample. Kenneth Fuller writes about this, and other modern myths taught as science. He hypothesized that this myth arose from the publication of a wide sample of snow crystals by Wilson Bently in 1931…

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The answer: yes and no. When applied to toilets and sinks, this is one of those “too good to be true” science factoids, I’m afraid. But it does apply in some situations.

The myth goes that if you flush a toilet in Australia the water swirls down the drain the opposite way than in the northern hemisphere, due to the Coriolis effect

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polar-bear.jpgThere’s this myth floating around that polar bear fur is fiber optic. It’s not. It’s not it’s not it’s not.

The myth goes like this… polar bears are white, but they have to keep warm in the winter. But white reflects light and heat, so how do they do it? By having fiber optic fur. “Fiber optics” are a type of “light pipe” that channels light extraordinarily well, sort of like an electric wire does for electric current. So, this is supposed to heat them up by channeling light to their black skin.

This is based on research that showed that polar bears are white to you and me, but don’t emit any ultraviolet (UV) light (they’re black in the ultraviolet). They thought the UV radiation was being absorbed by fiber optics and transported to the skin. It turns out instead that polar bear fur just absorbs UV on its own because of what it’s made of. So this is an example of an early, incorrect science report getting circulated and taking hold in the popular mind.

This myth gets perpetuated by the fact that polar bear fur is hollow. Fiber optics are also hollow, but not every hollow thing is a fiber optic (this is like the “a square is a rectangle but a rectangle isn’t always a square” thing).

Paul D. has an SEM picture of polar bear fur on his website (and some more information).

I was interviewing a scientist/economist (who does a lot of popularization of science) once and he mentioned that “polar bear is fiber optic” as he was discussing solar energy. I told him that, indeed, I had only recently found out that that is a myth, and asked him to retake his answer without that reference (since this was for radio). He did, but I thought his manner was odd. I saw him speak — for a LIVE TELEVISION BROADCAST — on solar energy a few weeks later. And while I sat there flabbergasted in my seat, he repeated the “polar bear is fiber optic” myth right there in front of the cameras!

Do a Google right now for “polar bear fur fiber optic” and you’ll find a variety of links, many of which shed doubt (and some which don’t) on this myth. I wonder if he researched the topic and found something compelling to convince him it was true, or whether the story was just too good to drop? So, this is how myths are perpetuated.

windowHave you been told that glass is a liquid? I remember back in 10th grade and my teacher told me that old windows were thicker at the bottom than at the top, showing that glass flows, veeerrrry slowwwwly.

While I was at the Exploratorium, this myth was debunked for me by my mentor Paul Doherty. It is true that many old windows are thicker at the bottom than at the top, but it’s not because glass flowed over time and puddled at the bottom. Old windows were made by spinning the molten glass and then cutting it into panes, resulting in glass that was thicker at one end than the other. In fact, later observations noted that some ancient glass is thicker at the top than at the bottom. It just depends on how the window was placed.

Paul notes on his website that: Room temperature glass has a viscosity of 1022 poise. The viscosity of a liquid controls how fast it flows under gravity. (SAE 30 motor oil has a viscosity of about 1 poise, water is 0.01 poise.) The viscosity of glass is so high that you could wait the entire age of the universe and see no measurable thickening of the glass under earth gravity.

Note that the definition of a solid is a material with a viscousity greater than 13 poise.

Of course, as Paul likes to say, “it’s more complicated than that.” Some people say that glass is both liquid and solid because when you look at the underlying structure of it, it has properties of both. But in terms of its material properties (does it flow!?) it can be classified as a solid. But the answer really isn’t that cut and dried.

Here is a link with more information than you’ll probably want to know.