10. The Great Wall of China, the Scar of the Earth
photo: Nicolas Perrault III / Wikicommons
The Great Wall of China is the only man-made structure visible on Earth from the moon.
Error. The Apollo astronauts, who actually stood on the moon and viewed the Earth from there, did not in fact report any man-made objects that they believed they recognized during the period when the Earth was illuminated by the sun. In contrast, light from urban areas is particularly visible when looking at the nighttime Earth from the moon.
Even from Earth’s orbit (at an altitude of ‘only’ 290 kilometers), the Great Wall of China is difficult to see, according to astronaut Jay Apt. According to ISS captain Chris Hadfield, the Wall is difficult to see because it is “thin and dung-colored.” The Chinese should therefore have given it a different color if they wanted to be visible from the universe.
9. Meteorites are hot fireballs
photo: Navicore / Wikicommons
A meteorite reaching Earth is a hot flaming fireball.
Before we go any further in this topic, a few words: a meteorite is a rock (or boulder of some other type of material) that has worked its way through the Earth’s atmosphere and has not been completely burned in the process. A meteoroid is a rock that floats (fly, shoots, wanders, whatever you want to call it) through the vacuum universe. When such a meteoroid enters our atmosphere, it produces a light trail. This light trail is a meteor. A meteor is also sometimes called a shooting star but this is wrong because a) it is not a star that falls, but a meteoroid (these are much smaller than stars!) and b) a meteor itself is only the light trail of a falling star object.
Anyway, when a meteoroid bores through the atmosphere, it forms a meteor, and if the matter still exists after the rough flight through the atmosphere layers, we call the remaining piece of rock a meteorite. Meteorites, when they reach planet Earth, are rarely warmer than freezing (in fact, they are almost always below freezing, due to their long time in the cold universe). The hot fireball causing the trail of light has already been extinguished many miles above the Earth’s surface, because the meteorite’s speed has dropped so drastically by then that not enough force can be applied to reach these temperatures. In fact, a meteorite loses all the heat it has gained in the last few miles of its flight to the Earth’s surface.
8. Friction creates heat from objects entering the atmosphere
photo: C m handler / Wikicommons
Wrong, of course, as you expected. It’s not the friction, but something called adiabatic air compression. That is an expensive word for a process that can be roughly explained as follows: energy can express itself in either mass or heat (or other forms, but that aside). If an object falls to earth under intense pressure, the mass of the object decreases, and because energy is not simply lost, the temperature rises. Thus, the internal heat of the object rises due to the air pressure in front of the meteorite. This is the main cause of the heat that eventually creates the meteor, the light trail.
Incidentally, friction also causes heat. However, it is not the only, nor the strongest, contributing factor to the warming of a meteorite.
7. Glass is a liquid
photo: Chmouel Boudjnah / Wikicommons
Scientifically speaking, glass is a liquid at room temperature because it flows like other liquids at this temperature. This can be clearly seen in very old stained glass windows, where the glass at the bottom is often thicker than at the top.
This misconception has to do with the confusion that a property of liquids (flowing or ‘flowing out’) is equated with the phase itself. Every substance has three phases, gas formation (at high temperatures), liquid and finally solid at the coldest temperatures. Most metals are solid at room temperature (although mercury is an exception, for example), and most liquids as we know them are (you can feel it coming) liquid at room temperature. Water, for example, is definitely below freezing (we’ve even adjusted our Celsius temperature scale to this!). Water is liquid between 0 and 100 degrees and above that it is gaseous.
One of the properties of a substance in the liquid phase is that it flows, or is liquid. In principle, a solid does not change shape regardless of the gravity acting on it, while a liquid will ‘flow’ downwards by that same gravity (unless another substance is already present). Think of a drop of water. We also know a frozen drop of water as an icicle, and it does not fall down. But when the substance enters the liquid phase (it melts, or in the case of water, it thaws) then gravity pulls the liquid down.
Well, that’s that. Now back to glass. Glass is not a liquid at room temperature, but an amorphous solid. Amorphous comes from ‘a’, or anti, and ‘morph’, or form. So formless. Glass only starts to flow above a certain (transition) temperature. The exact location of this temperature (range) is still a matter of debate among chemists, but at least glass is solid at room temperature.
How do we explain the stained glass effect? The answer is simpler than you think. First, it has never been scientifically proven that stained glass windows are always thicker at the bottom than at the top. In fact, examples have been found where the glass at the top is thicker. Second, during the stained glass heyday it was difficult to make glass of consistent thickness, so the thickness of glass varied quite a bit, and of course this was reflected in the windows they made. It is therefore impossible to say whether the thickness of glasses from that time has changed due to the flow of the glass. However, the suspicion is not.
6. Lucky strike
photo: Филип Романски / Wikicommons
When a coin falls head-up repeatedly, the chances of the other side falling are higher the following times. In other words, if you toss a coin ten times and it always falls face up, then the next time you have a higher chance of face down.
Probabilities are notoriously difficult to understand, even for statisticians trained in them, and certainly for ordinary people like you and me. Most people “feel” that if they roll a die repeatedly and get 6 each time, the odds of other numbers should increase (unless the die is faked, of course). Another example is the Roulette game: if the ball repeatedly lands on a black surface, and not once on red, it is considered more likely that the next round the ball will land on red.
We call this misconception, because it is common in the gamblers world, the gambler’s fallacy. In reality, when a die is not false (i.e. shows no preference for one of the six options), the probability of one of the numbers is always the same, regardless of how many times there has been a particular outcome before the roll. Whether you roll a run that looks like this: 4 – 5 – 2 – 2 – 1 – 4 or you roll this run: 6 – 6 – 6 – 6 – 6 – 6, it doesn’t matter, the chance of a six in the next round is exactly the same in both cases (namely one sixth).
5. Money with impact
If you throw a dime from the Empire State Building (381 meters high) the impact of this dime will be able to kill someone, or break a paving stone in half.
No, luckily. You will feed the people who are going to test this and throw duppies from tall buildings, because a coin of that height can pack a nice punch, but you can’t (just) die from it (unless the piece falls directly on your temple, or it scares you so much that you jump in front of a bus).
The final fall speed of a dime (actual myth speaks of a penny, but it is roughly comparable to our dime) is about 50 to 80 kilometers per hour. That speed is not enough for the object to enter your body, nor to break a pavement. The well-known Mythbusters have already tested this myth, and they came to the same conclusion.
4. Don’t let the building cool down!
photo: Brendel / Wikicommons
When the ambient temperature of a building is low (which is often the case in the Netherlands), it is much better for energy savings to keep the building at a stable temperature than to switch off the heating and leave the building overnight. let cool. In the latter case, the building has to put in an enormous amount of energy in the morning to heat up the entire building.
This is a (very understandable) mistake. The story sounds very plausible, but research has shown that it is not the case. In principle, a building that is ‘allowed’ to cool down during the night does not have to spend disproportionately more energy on heating, in contrast to the amount of energy required to keep the building at temperature throughout the night. In fact, turning off the heating can yield savings of up to 15%, although this of course depends on the amount of energy the building loses to its environment (this has to do with factors such as insulation, outside temperature, wind and so on! ).
In other words, if you go on holiday, just turn the heating down (but if you live in Sweden, then don’t, because if your pipelines freeze you’re really sour!).
3. Lightning never strikes the same place twice
photo: smial / Wikicommons
A lightning bolt never strikes the same spot as before.
Unfortunately this is an untruth. There’s no reason lightning shouldn’t strike in the same spot. The first thunderbolt has nothing “to do” with the second, so there’s no sort of “memory” in the thunderstorm that remembers to stay original and hit elsewhere.
In fact, a lightning conductor on a house or other building is designed on the idea that lightning can and will strike in the same place. That’s the whole idea behind it: to ‘distract’ lightning so that it strikes one place, rather than unpredictable (potentially dangerous) places elsewhere.
Going back to the Empire State building (which we just threw dimes from), this building is struck by lightning about a hundred times a year. If thunder never strikes the same spot more than once, then this is a magical exception.
2. The Inventor of the Light Bulb
Thomas Edison is the inventor of the light bulb, or light bulb.
No, Thomas did not invent the light bulb. He is, however, the inventor of the first useful incandescent lamp, in 1880. Joseph Swan invented an even more useful incandescent lamp a year later, but by then the novelty had worn off, so we remember Edison’s name in relation to the light bulb. However, the German Heinrich Göbel was the first to successfully make an incandescent light bulb (as early as 1854). His lamp burned for about 400 hours before the wire burned out. When Edison applied for a patent on the same type of lamp some 25 years later, Göbel challenged this patent application, but died a year later. So Edison got all the credit.
1. Airplane toilets dump their waste directly over our heads
photo: Kristoferb / Wikicommons
When you use the toilets on an airplane, the waste is immediately dumped during the flight.
This is not standard practice, at least not the official rule. Officially, all aircraft waste is collected and stored in tanks and these are emptied onto the ground. When liquids do leak from an aircraft, this is sometimes referred to as ‘blue ice’. However, this is a faulty leakage in the waste tank, by no means the intention! Planes keep their mess neatly inboard.
Trains, on the other hand, by no means do that. It is not without reason that the passenger is requested not to use the toilets on the platforms themselves. After all, the waste is dumped immediately, so if you do your defecation in a stationary train in a station, everyone can see that message the moment the train leaves. Think about that the next time you cross a train track, on foot… (the newest trains nowadays have a collection tank that collects all the faeces!)
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