Things you Always Thought You Knew

For quite a while now, I’ve made a small project of collecting things that everyone knows are true, but really aren’t true anyway. I’ve been working on this project on and off for quite some time, and come up with a few examples of such “common knowledge” so far. For example:

“It takes the police 2 minutes (or sixty seconds or some other amount of time) to trace a phone call.”

This has long been a staple of bad Hollywood thrillers–“Keep him talking! Keep him talking!”–but the fact is, tracing a phone call takes zero seconds. The call is traced before the phone has finished ringing. You don’t even need to answer it.

“There are three states of matter.”

Actually, there are six states of matter: Einstein-Bose condensate, superfluid, solid, liquid, gas, and plasma. Of the six, five occur naturally thorughout the universe (Einstein-Bose condensate occurs only in the lab); and four of those–solid, liquid, gas, and plasma–occur naturally on Earth.

“Someone who passes out on his feet will fall over backward.”

Also a staple of Hollywood. In reality, if you lose consciousness standing up, you fall over forward.

“There are three primary colors.”

The human visual system responds to photons with a wide range of diffeent wavelengths. Most people have three distinct receptors in their eyes, which are maxinally sensitive to a relatively narrow range of wavelengths; however, all three receptors do respond to all visible frequencies of light. (Some people have only two kinds of receptors; these people have red-green color blindness. A few people have four, and can distinguish colors most people can’t.)

Because all the receptors do respond to all frequencies of visible light, it is impossible to model certain colors based on any one set of primaries. For example, pure, 100% saturated yellow can not be modelled by any combination of red, green, and blue light. You can get yellow, but you can’t get pure yellow.

“Science says bumblebees can’t fly.”

Actually, science says bumblebees are aerodynamically unstable, which means they can’t glide. Many things that are aerodynamically unstable can fly–including bumblebees and Stealth fighters.

An aerodynamically unstable object can fly if it has an active stabilization system. In a bumblebee, that system is the animal’s sensory apparatus, brain, and muscles; in a Stealth fighter, it’s the plane’s gyroscope, onboard computer, hydraulics, and control surfaces.

In all such objects, if the active stabilization fails, the thing glides about as well as a rock.

“The Eskimoes have fifteen words for snow.”

This idea comes from a linguistic hypothesis called the Sapir-Whorf hypothesis, which postulates that a civilization will develop more words for concepts that are most important to it. In practice, it doesn’t quite work that way.

The Eskimoes have three words for “snow,” which translate roughly as “snow,” “sleet,” and “slush.” They also have a distinct word for snow on the ground versus snow in the air, but then, so does English; “blizzard” and “snowstorm,” as distinct from “snow.”

“The rubber tires on a car will protect the car’s occupants from lightning.”

This common misconception is downright dangerous. Yes, rubber is an insulator; however, rubber tires and rubber-soled shoes offer zero protection from high voltage. Air is also an insulator! Anything that can get through six miles of air is not going to stop for a few inches–or even a few feet–of rubber.

You are safe in a car, provided you do not touch any metallic object, because of the shape of the car, and its construction, not because of its tires. The electrical discharge will tend to travel around the car’s metallic shell, rather than passing through the metallic body and into the car. Rubber-soled shoes do not protect you from lightning (or other high-voltage discharges) one little bit.

“Water conducts electricity.”

Another common misconception about electricity. Pure water is an insulator. It does not conduct electricity. Water becomes a conductor only if there is a polar compound, such as salt, dissolved in it. It’s actually the salt (or whatever) that is carrying the electricity–not the water.

30 thoughts on “Things you Always Thought You Knew

  1. Gold star for Franklin

    things that make you go hmmm…printing that one out with your permission to share with the office.
    The only 2 I knew were about fainting and water being an insulator.

  2. Gold star for Franklin

    things that make you go hmmm…printing that one out with your permission to share with the office.
    The only 2 I knew were about fainting and water being an insulator.

  3. Gold star for Franklin

    things that make you go hmmm…printing that one out with your permission to share with the office.
    The only 2 I knew were about fainting and water being an insulator.

    AJ (forgot to sign…)

  4. Gold star for Franklin

    things that make you go hmmm…printing that one out with your permission to share with the office.
    The only 2 I knew were about fainting and water being an insulator.

    AJ (forgot to sign…)

  5. all true save one:

    there are three “primary” colours. Green is not one of them. Yellow is the third primary, and through the use of red, green and blue (that is, pure of each) you can get every other colour in the visible spectrum.

    However, there is nothing primary about those three components when you are referring to the electromagnetic spectrum as a whole.

    -me

    • Nope, with red, yellow, and blue, you can’t produce the full range of the visible spectrum. Colors outside the RBY gamut include deep, saturated fire-engine red, very dark navy blue, and cyan.

      There are several trichromatic color modelling systems, including CMY (cyan, magenta, yellow–what color photographs use), RBY (red, blue, and yellow–what they teach you in school), and RGB (the standard additive color model). Not one of them can produce the full range of visible colors.

      CMYOGK (aka “Hexachrome” color–cyan, magenta, yellow, orange, green, and black) comes closer than any of the trichromatic color models tomodelling all the visible shades of color, but it still can’t model them all; fully 80% of the Pantone color library, for example, is outside the CMYOGK model.

  6. all true save one:

    there are three “primary” colours. Green is not one of them. Yellow is the third primary, and through the use of red, green and blue (that is, pure of each) you can get every other colour in the visible spectrum.

    However, there is nothing primary about those three components when you are referring to the electromagnetic spectrum as a whole.

    -me

  7. > “It takes the police 2 minutes (or sixty seconds
    > or some other amount of time) to trace a phone call.”

    Yep, it’s called CallerID and the Police/Emergency Services can’t be blocked. They have reverse phone number lookups that list the exact location.

    However….

    Cell phones by their nature can’t be localized quickly (though that too will change soon) and PBXs only take it down to a building or set of buildings.

    > “There are three states of matter.”

    > …. and four of those–solid, liquid, gas, and
    > plasma–occur naturally on Earth.

    I love pointing to a fire and asking “What state of matter is that?”

    > “There are three primary colors.”

    This explination mixes two seperate but related concepts.

    The primary colors of electro magnetic radiation that the human eye is most often sensitive to.

    verse

    The primary colors of a surface that reflects electro magnetic radiation.

    This was the topic of an ENTIRE photo class I took years and years ago.

    > “Science says bumblebees can’t fly.”

    Coolness.

    As they used to say in the USAF, “you strap a big enough engine onto a brick and it will fly.” Hense the F-14.

    > “The rubber tires on a car will protect the
    > car’s occupants from lightning.”

    It’s a downed power line engry they protect you from.

    {safety hat on}

    If you ever crash into a power pole, don’t get out of the car.

    That 6 inches of rubber will keep you getting zapped from “local” line voltage, but your 1/4 inch in your shoes wont.

    > “Water conducts electricity.”

    Soap and skin oils in a bath are the conductors for radios and hair driers.

    • “Cell phones by their nature can’t be localized quickly…”

      That’s already changing; I’ve seen ads for consumer-grade phones with built-in GPS. Dunno why anyone needs em, but that’s another story.

      “I love pointing to a fire and asking “What state of matter is that?””

      Ooh! Ooh! I know! It’s incandescent gas. 🙂

      “This explination mixes two seperate but related concepts.”

      Well, yeah. But my point was that red, green, and blue together do not make white–not really–and that some colors found in nature can’t be produced by mixing ANY three primaries, in additive OR sutractive color models.

      “That 6 inches of rubber will keep you getting zapped from “local” line voltage, but your 1/4 inch in your shoes wont.”

      Yep. And you don’t want to see what happens to someone who is exposed to line-level voltage without protection.

      I have a client that makes a storm and lightning detection device, which is sold both to consumers and to the power and electrical safety industry. I prepared a multimedia presentation for them on the dangers of high-voltage electricity. part of the multimedia presentation is a police videotape of a man dusted out of his mind on PCP who was fleeing the cops; he tried to get away by climbing a power pole.

      In one frame, you see him reaching for the wire. In the next frame, all you see is an enormous fireball with the shape of an arm sticking out of it. In the next frame, he’s being thrown clear of the pole, trailing fire all the way down. Nasty stuff.

      So: What he said. If you hit a power pole and bring down a line, don’t get out of the car (and don’t touch anything metallic IN the car).

      • I just happened to looking down a alley way once, when a crow missed it’s landing on the top of a power pole.

        One wing on each wire.

        A rather loud bang.

        A burst of feathers floating down.

        Rumor had it that they didn’t find any bits of meat, just feathers.

  8. > “It takes the police 2 minutes (or sixty seconds
    > or some other amount of time) to trace a phone call.”

    Yep, it’s called CallerID and the Police/Emergency Services can’t be blocked. They have reverse phone number lookups that list the exact location.

    However….

    Cell phones by their nature can’t be localized quickly (though that too will change soon) and PBXs only take it down to a building or set of buildings.

    > “There are three states of matter.”

    > …. and four of those–solid, liquid, gas, and
    > plasma–occur naturally on Earth.

    I love pointing to a fire and asking “What state of matter is that?”

    > “There are three primary colors.”

    This explination mixes two seperate but related concepts.

    The primary colors of electro magnetic radiation that the human eye is most often sensitive to.

    verse

    The primary colors of a surface that reflects electro magnetic radiation.

    This was the topic of an ENTIRE photo class I took years and years ago.

    > “Science says bumblebees can’t fly.”

    Coolness.

    As they used to say in the USAF, “you strap a big enough engine onto a brick and it will fly.” Hense the F-14.

    > “The rubber tires on a car will protect the
    > car’s occupants from lightning.”

    It’s a downed power line engry they protect you from.

    {safety hat on}

    If you ever crash into a power pole, don’t get out of the car.

    That 6 inches of rubber will keep you getting zapped from “local” line voltage, but your 1/4 inch in your shoes wont.

    > “Water conducts electricity.”

    Soap and skin oils in a bath are the conductors for radios and hair driers.

  9. That’s a good list… but allow me to pick nits (as is my want):

    There are three primary colors.

    There are several color systems in which there are three “primary” colors. Red/Yellow/Blue for pigments. Red/Blue/Green for light. You can make anything appear like a myth if you choose a suitably narrow definition. But if you choose the commonly accepted definition of a term, in this case there certainly can be three primary colors.

    Science says bumblebees can’t fly.

    Actually, until 2000 (Cornell press release) there was no model which could assign enough lift to a bumblebee. New computational models finally figured out how the goddess made those flying machines by taking wake turbulence into account. So this one was true when we (or at least many of us) were in school. It’s actually a great way to show that what science gives us isn’t truth but theories and models… and that sometimes we know they aren’t perfect!

    But I repeat – good list, and good luck collecting more!

    • You can create color systems with three “primary” colors, but many people believe that this means all colors are made up of mixtures of these three–which isn’t true. Your eye responds to many shades of light; when you see yellow light, it’s not made up of “red” photons and “green” photons, it’s made up of “yellow” photons. And so forth.

      All trichromatic color systems (even RGB!) can not reproduce the full range of visible colors.

      I work prepress professionally; color theory is one of my specialties. 🙂

  10. That’s a good list… but allow me to pick nits (as is my want):

    There are three primary colors.

    There are several color systems in which there are three “primary” colors. Red/Yellow/Blue for pigments. Red/Blue/Green for light. You can make anything appear like a myth if you choose a suitably narrow definition. But if you choose the commonly accepted definition of a term, in this case there certainly can be three primary colors.

    Science says bumblebees can’t fly.

    Actually, until 2000 (Cornell press release) there was no model which could assign enough lift to a bumblebee. New computational models finally figured out how the goddess made those flying machines by taking wake turbulence into account. So this one was true when we (or at least many of us) were in school. It’s actually a great way to show that what science gives us isn’t truth but theories and models… and that sometimes we know they aren’t perfect!

    But I repeat – good list, and good luck collecting more!

  11. You can create color systems with three “primary” colors, but many people believe that this means all colors are made up of mixtures of these three–which isn’t true. Your eye responds to many shades of light; when you see yellow light, it’s not made up of “red” photons and “green” photons, it’s made up of “yellow” photons. And so forth.

    All trichromatic color systems (even RGB!) can not reproduce the full range of visible colors.

    I work prepress professionally; color theory is one of my specialties. 🙂

  12. “Cell phones by their nature can’t be localized quickly…”

    That’s already changing; I’ve seen ads for consumer-grade phones with built-in GPS. Dunno why anyone needs em, but that’s another story.

    “I love pointing to a fire and asking “What state of matter is that?””

    Ooh! Ooh! I know! It’s incandescent gas. 🙂

    “This explination mixes two seperate but related concepts.”

    Well, yeah. But my point was that red, green, and blue together do not make white–not really–and that some colors found in nature can’t be produced by mixing ANY three primaries, in additive OR sutractive color models.

    “That 6 inches of rubber will keep you getting zapped from “local” line voltage, but your 1/4 inch in your shoes wont.”

    Yep. And you don’t want to see what happens to someone who is exposed to line-level voltage without protection.

    I have a client that makes a storm and lightning detection device, which is sold both to consumers and to the power and electrical safety industry. I prepared a multimedia presentation for them on the dangers of high-voltage electricity. part of the multimedia presentation is a police videotape of a man dusted out of his mind on PCP who was fleeing the cops; he tried to get away by climbing a power pole.

    In one frame, you see him reaching for the wire. In the next frame, all you see is an enormous fireball with the shape of an arm sticking out of it. In the next frame, he’s being thrown clear of the pole, trailing fire all the way down. Nasty stuff.

    So: What he said. If you hit a power pole and bring down a line, don’t get out of the car (and don’t touch anything metallic IN the car).

  13. Nope, with red, yellow, and blue, you can’t produce the full range of the visible spectrum. Colors outside the RBY gamut include deep, saturated fire-engine red, very dark navy blue, and cyan.

    There are several trichromatic color modelling systems, including CMY (cyan, magenta, yellow–what color photographs use), RBY (red, blue, and yellow–what they teach you in school), and RGB (the standard additive color model). Not one of them can produce the full range of visible colors.

    CMYOGK (aka “Hexachrome” color–cyan, magenta, yellow, orange, green, and black) comes closer than any of the trichromatic color models tomodelling all the visible shades of color, but it still can’t model them all; fully 80% of the Pantone color library, for example, is outside the CMYOGK model.

  14. I just happened to looking down a alley way once, when a crow missed it’s landing on the top of a power pole.

    One wing on each wire.

    A rather loud bang.

    A burst of feathers floating down.

    Rumor had it that they didn’t find any bits of meat, just feathers.

  15. A few people have four, and can distinguish colors most people can’t.)

    I believe these are all female, and tend to have sons that are colorblind(though I don’t remeber which variant of colorblindness)

    • Yep. Due to a genetic quirk in the way information for color receptors is coded, only women can be tetrachromats…and there’s a good chance most of their male offspring will have red-green (IIRC) color blindness.

      Color blindness rarely manifests in women, and the gene for red-green color blindness is inherited from the mother. Kind of like male-pattern baldness.

  16. A few people have four, and can distinguish colors most people can’t.)

    I believe these are all female, and tend to have sons that are colorblind(though I don’t remeber which variant of colorblindness)

  17. Yep. Due to a genetic quirk in the way information for color receptors is coded, only women can be tetrachromats…and there’s a good chance most of their male offspring will have red-green (IIRC) color blindness.

    Color blindness rarely manifests in women, and the gene for red-green color blindness is inherited from the mother. Kind of like male-pattern baldness.

  18. “There are three states of matter.”

    Your right that there are six states of matter, but you are wrong about what they are. Superfluid is an Einstein-Bose condensate. The sixth state of matter is filament such as ion jets, solar flares, and lightning.

  19. “There are three states of matter.”

    Your right that there are six states of matter, but you are wrong about what they are. Superfluid is an Einstein-Bose condensate. The sixth state of matter is filament such as ion jets, solar flares, and lightning.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.