Things You Always Thought Were True
... But Really Aren't


  1. Butter or Raw Meat is Good for a Burn
    Your grandmother believed this. Now medical science has shown that these are the worst things you can do for a burn. The best remedy is running cold water, or ice shaped over the burned area (bags of frozen vegetables are ideal). In fact, prompt treatment of even a bad burn with these, if applied for at least half an hour, has been shown to remarkably reduce the healing time and the severity of the burn.

  2. Hot Water Freezes Faster Than Cold Water
    People who make backyard skating rinks often state this when asked why they apply a layer of hot water to the ice surface. Actually, the hot water is necessary to melt the top layer of ice and the bumps, leaving a smooth surface. But under certain conditions water might freeze faster if it's hot. We did the experiment ...find out more here.

  3. Skates Work Because They Melt a Layer of Water
    How skates work on ice has been a subject of controversy for decades. There are actually three factors at work ... let's have a look at each:

      Pressure from the blade reduces the freezing point and causes a thin layer of ice to melt
      This is true, but its effect is negligible. A 90 kg skater skating on blades that are 3 mm wide and with a contact length of 10 cm will exert a pressure of about 1400 kPa on the surface of the ice. Unfortunately, to reduce the freezing point of ice by just 1 degree C requires a pressure ten times as large as this. So an average hockey player will be lowering the freezing point of water under his skates by a mere 0.1 deg C; this will only be a factor (and a minor one at that) when the temperature of the ice is near 0 degrees.
      Moreover, at temperatures below -20 deg C, the pressure of the skate blades actually raises the freezing point, making the ice slightly less slippery.

      The friction between the blade and the ice melts the ice and forms a thin layer of water
      The amount of heat generated by friction has been calculated ... it can be as much as about 2 deg C. So this factor is far more important to slipperiness than pressure. However, there's a problem! Ice on most skating rinks is kept at a temperature of between -5 and -10 deg C. So a 2 degree increase caused by friction won't melt it! This effect will only be noticeable when the ice temperature is near 0 degrees.

      The top layer of the ice is really a 'quasi-fluid'
      This is the true reason why ice is slippery. It has to do with the properties of water when it forms ice, and it is a relatively recent discovery. When they turn to a solid, water molecules link up in hexagonal patterns (because they are polarized and can form hydrogen bonds), and these hexagons form large sheets ... layer upon layer of sheets. The molecules inside a sheet are attracted to each other more strongly than to molecules in the sheets above and below. This means that the sheets can easily slide back and forth relative to the sheets above and below. A small sideways force from a skate will cause these layered sheets to slide, acting just like rollers on a conveyor belt.
      Another property of ice is that the molecules on the surface are more attracted to things passing over it than they are to the other molecules of ice on the surface. The unfilled bonds of the surface molecules can grab at anything that comes near ... like your foot ... and be pulled out of the surface of the ice. Once they become detached they can 'roll around' on the surface of the ice like tiny ball bearings, making the surface slippery.

    In summary, ice's slipperiness has very little to do with the pressure of the skate or the heat of friction. Rather, it's mostly due to the crystal properties of ice itself, particularly near the surface.

    Information for this topic was obtained from Alain Haché's excellent book 'The Physics of Hockey'

  4. The Past is Unknowable
    Is time travel into the past really impossible? Could we at least see or hear what went on 500 or even 10,000 years ago?
    There are several answers to this question. Some possibilities to consider:

      - Light moves at a definite (although very large) speed. How current the image of something we're looking at depends on how far away it is. The sun, for example, is far enough away so that it's light takes about 6 minutes to get here, so the sun you're looking at is really the sun of 6 minutes ago. You're looking at the sun 6 minutes in the past. The farther away something is, the more distant into the past we're seeing it. Most of the stars you see at night, which are incredibly far away, are what they looked like many many years in the past. So we CAN see the past!
    (For more information along this line, visit our 'How Far Can You See' page.)

      - Some scientists believe that sounds made by humans in the distant past may accidentally have been recorded; for example, a pottery wheel is a very low-grade sound recording instrument that works just like the methods that used to be used to make vinyl long-playing records. They believe that it might be possible to recover background sounds accidentally 'embedded' into the pottery.

  5. Heavy Objects Fall Faster Than Light Objects
    They don't, normally. The problem is that on earth where we are, there's air. And falling objects have to push through it to reach the ground. The 'air resistance' may cause some objects to accelerate less quickly than others, so that they do indeed fall slower. But it's the amount of air resistance that an object has that makes it fall slower, not its mass.
    In a vacuum (on the moon, for example, or just inside a big glass cylinder that has had all the air removed), a bowling ball and a feather, dropped from the same height, will reach the ground at the same time. You can see this effect for yourself if you drop a ping-pong ball and a golf ball from an equal height. Their air resistances are about the same; you'll see them hit the ground at almost the same time, despite the fact that the golf ball is much heavier.
    There is an amazing video on YouTube showing a bowling ball and feather falling many tens of metres inside a tall plastic tube from which the air has been removed. They fall side by side and hit the ground at exactly the same time! Watch it here.

  6. Lightning Never Strikes the Same Spot Twice
    Not true! In ordinary circumstances, the chances of being struck by lightning at all are pretty slim, but if the object in question is taller than its surroundings, it stands a good chance of being struck in a bad storm. Trees are always being hit by lightning, but seldom more than once because either they get knocked down, or there are lots of other trees just as tall all around.
    The easiest way to be convinced that lightning can really strike many times at the same spot is to look at structures that aren't damaged when they're struck. Tall buildings like the C.N. Tower, or the Empire State Building, for example, can be struck many times in the course of just one bad storm!

  7. Somwhere On Earth Everyone Has an Exact Double
    ... or, 'I have a twin somewhere'. Many people believe this, because it seems to make sense. After all, there are six billion people on earth, so the chances should be good, right?
    Wrong! First of all, assuming you are Caucasian, the chances that one of the two or three billion Asian people (in China, India, etc.) looks like you is about zero. Now, depending on your heritage, (Scandinavian, Middle Eastern, Anglo-Saxon, for example), there is an even smaller population base in which your 'twin' can be found. Here's what we mean. If you are a Caucasian, with blonde hair, there are considerably less than half a billion of this type of 'person' on earth. So your chances of finding a twin are reduced by about a tenth.
    But it's even less than that. There are hundreds of facial 'features' that make up the face that you see in the mirror every morning; changing even one of them slightly would result in a face that wouldn't be a twin. There are so many possible combinations that the likelihood of finding someone that exactly resembles you is probably very slim.
    However, the chances of some faces being the same are actually high. There may in fact be many sets of people who look the same; it's just that the chances of it being you are not very high. This is analogous to winning a lottery. For every draw, there might be hundreds of cash prize winners. But that doesn't change the fact that YOUR chances of winning are still next to nothing. There have to be winners, but they don't have to (and probably won't) be you!

  8. Astrology Works
    Astrology is a fake science that's been around for thousands of years. In fact, a massive study done in Britain proved conclusively that there is no correlation between astrological sign information and reality. We've written about this in some detail on our 'Pseudoscience' page, where you can also learn why Water Witching, Faith Healing, and other 'pseudosciences' are really not what they seem.

  9. _______ Doesn't Have to Be True ... It's Just a Theory
    [Insert your own favourite theory that you don't believe]
    So what is a theory, anyway? Probably not what you thought. If something isn't right, does it have to be wrong? Nope! There is a theory that the earth is round like a ball. It's quite common. Do you believe it?
    You shouldn't ... it's not correct. The earth is actually fatter in the middle, sort of like a football. But not so you'd notice; it takes careful measurement to discover the 'truth'. You can't even tell by looking at it!
    But that doesn't change the fact that it is mostly correct to say that the earth is a sphere. Similarly, when asked to state how far it is to the next town, you might say '20 kilometres', when that's not correct (it's actually 21.7239 km).
    Theories in science are like that. Everybody who understands a theory may agree that it's mostly correct, but not entirely. Newton's theory of gravity is another good example. Most people would agree that when you drop a ball, it falls to the ground. This theory is mostly correct. Actually, the ball falls 99.99999999% of the way to the ground; at the same time, the earth moves up 0.00000001% of the way, to meet the ball. But it's not wrong to say that the ball just falls ... it's just not 100% correct.
    Another good example is climate change, sometimes called global warming. This is a theory, with overwhelming evidence to support it. Nevertheless, it's a theory, so it can't be 'proved' (see the link below) ... at least, until most of Florida ends up underwater!
    Another difficulty with this theory is that people don't understand it. "Look at all the snow and coold weather we've been having! How can the earth be warming up?" People confuse weather like that with climate, which affects the whole earth. Climate change as a theory tells us that weather will fluctuate wildly around the globe, but the average temperature of the whole earth will slowly increese. Both of these phenomena have been directly observed and measured.
    'Theories' and why they can be 'mostly right', but not 'wrong', are discussed in more detail on our Theories in Science page.

  10. Your Truck Will Take Off Faster If You Floor the Gas Pedal
    This is a myth that most high school-age males seem to believe, probably because they think that a lot of spinning tires, smoke, and noise implies lots of power. In fact, you can accelerate faster with a slow and steady acceleration. If your wheels spin, it means you've lost traction, and are no longer accelerating the vehicle. Drag car racers who use stock equipment don't get a quick start if their tires spin, so they don't do it.
    (Dragsters with big balloon tires are a different story, however. Spinning their tires causes the rubber to melt, providing greater traction, so they give up a little bit of acceleration in the first second or so, to get more later with 'sticky' tires.)
    As long as we're on this topic, we might as well destroy the myth (teen-age males again) that spinning a vehicle in circles ('donuts') shows the power of their vehicle or maybe the great skill they have behind the wheel. Unfortunately, neither is true. You can do this with a 4-cylinder 20-year-old rust bucket just as easily, even if it's an automatic. And a friend of mine once taught his 15 year old, non-driving sister how to do donuts (in a parking lot)!
    And let's talk about the rubber! Laying down strips of rubber when accelerating from a stop, or doing donuts, costs you money! I had a Physics class calculate this once, using real examples of tires on one of their vehicles and real costs, based on a 1 mm thickness of rubber left on the road several metres in length. For a good set of tires, based on the depth of the tread, and making the assumption that the tires would be replaced when the tread was gone and they were bald, we calculated that each time you lay down rubber on the road, it costs you $10-20!

  11. HIV or AIDS is a 'Gay' Disease
    Maybe it once was, but not any longer. More people now have the disease who are heterosexual. And there's more bad news ... it's everywhere. Even in a small community, a person who has frequent, unprotected sex with many different partners has a significant chance of contracting some form of STD, even HIV. This is probably the best argument for chastity until marriage. There is no cure for herpes, or for AIDS.

  12. Handguns Don't Kill People, People Kill People
    True enough. But in every country where there is relatively free access to handguns, the rate of injury or death due to handgun use is higher. Sometimes a lot higher. People are always going to get into arguments and try to kill each other; its just far deadlier for the victim if the other person has easy access to a gun.
    Some frightening facts:
      - In some U.S. cities, as many as one out of every three adults has a handgun in their car or bedroom. Not surprisingly, these same cities show the highest rates of gun-related deaths.
      - The vast majority of handgun injuries and deaths are the result of an argument between two people who know each other. In other words, guns aren't being used by criminals to cause most of these deaths, but by ordinary people who have easy access to a gun when they're angry. This statistic puts the lie to the argument that restricting handguns won't take them out of the hands of criminals, only ordinary citizens, because it's mostly the ordinary citizens who are using them to kill people in the first place!.


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