Three Lies You Learned in School
Ask Science explores 3 lies students often learn in school and the true facts behind them.
Lee Falin, PhD
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Three Lies You Learned in School
One of the interesting things about science is how hard it is for new discoveries and ideas to trickle down to the elementary education level. I’ve always felt there were two reasons behind this.
The first is that it takes a surprisingly long amount of time for information uncovered in new research to make it into textbooks. Some branches of science change so quickly (especially biology) that many textbooks are incorrect at the time of printing.
Another reason is that many people believe they know a fact already, since they learned it in school when they were kids. So they never bother checking to see if that fact is still true. Let’s look at some common examples..
How Airplanes Fly
One of the most persistent falsehoods in modern education is how airplanes fly. Most people know that airplanes fly because a force, commonly called lift, is applied to the wings. But if you ask a hundred random people what causes this lift, I’m willing to bet that over half of them will tell you some version of the equal transit time theory.
See also: Simple Machines: Lifting with Levers
This theory says that when the wing is moving through the air, the air is split in half by the wing. Since the upper surface of the wing is curved, the air has to travel a greater distance than the air underneath the wing. So in order to keep up with the air underneath the wing, the upper part of the air has to travel faster. Faster moving air results in lower pressure, and since the pressure above the wing is lower than the pressure below the wing, we get lift! Right? Wrong.
The problem with this theory is that the upper part of the air doesn’t care one bit about keeping up with the lower part of the air. Unfortunately this theory is so popular that it still exists in modern textbooks and even some pilot manuals. There are several other incorrect or partially correct explanations about why airplanes fly, but the truth is fairly complicated. For a full explanation, check out NASA’s excellent “What is Lift” website.
How Evolution Works
Assuming that they believe in evolution at all, many people believe that organisms evolve because of changes in their environment. For example, if the earth suddenly got really hot, animals might evolve to have less hair in order to adapt to that climate.
The problem with this approach to evolution is that it implies that evolution is some kind of conscious or unconscious change made by an organism, which is simply false. Organisms evolve when random genetic changes give them a survival advantage over organisms that don’t have those changes. For more details, check out my episode on Evolution and Super Goblins.
Why We Have Seasons
Ancient Greeks knew that the reason for the winter season was because for six months of the year Persephone, daughter of the harvest goddess Demeter, was in the underworld with her husband Hades. Mother and daughter missed each other so much during this time that the world languished in cold barrenness until they were reunited in the spring.
Had the Greeks gone to the trouble of visiting the southern hemisphere, they would have seen that perhaps southern Demeter didn’t love her daughter as much as northern Demeter did, because when it’s winter in the northern hemisphere, the southern hemisphere is experiencing summer time.
See also: When to Capitalize Seasons
An equally incorrect account of seasonal change taught to many of us is that in the winter the Earth is further from the sun…or at least the top half of the Earth is…somehow…even though it’s a ball…and connected to the bottom half…hmm.
In fact you might be surprised to learn that the Earth is actually furthest from the sun at the beginning of July, around 152 million km away, while in December it reaches its closest point to the sun, around 147 million km away. So what gives?
The real reason we have seasons is because Earth is tilted on its axis. During summertime in the northern hemisphere, the axial tilt is towards the sun, which results in the sun’s rays being able to strike the northern half of the planet more directly and for a longer amount of time than in the southern hemisphere.
During wintertime, the Earth is titled the other way, so the sun appears lower in the sky. This also causes the sun’s rays to be more spread out, and the amount of time those rays strike the Earth is shorter.
Conclusion
So now you know the truth about why airplanes fly, what causes different seasons, and how evolution works. The next time you’re flying in an airplane in the summertime watching Jurassic Park, be confident in the fact that you will be one of the few people who really knows what’s going on.
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Plane image from Shutterstock
