10 common science myths that refuse to die

The bad guys would hear James Bond's silencer from a mile away

We like myths when they’re the mysterious tales of legends from forgotten eras. We’re not so keen on science myths that have been thoroughly debunked but persist regardless. The most damaging myths usually have voices actively debunking them, which isn’t so bad. It’s good that people are making noise about climate change deniers. It’s important that people address myths like vaccines causing autism, HIV not causing AIDS, or the idea that things like homeopathy or detoxing actually work.

Although less immediately damaging are the little myths that have been around even longer and refuse to go away. Because they aren’t as controversial or dangerous, not as many people are actively debunking them. After all, it’s more important that people come to realise the truth about things like climate change. Nonetheless, here are 10 science myths commonly believed to be true that we wish would go away.

1. You can see the Great Wall of China from space

Image: Reddit/deadfermata

Of course you can’t. When astronauts are in the International Space Station, they’re about 400 km above the Earth’s surface. The Wall changes a lot over the thousands of miles it runs for, but its width is only about 10 m at its widest. It would be like spotting an ant from several miles away.

NASA have taken a few looks to see and have confirmed that it’s too small to make out and that the surrounding landscape appears to be the same colour as the wall anyway, making it even more difficult. The only merit the myth possibly has is that people can disagree over what exactly counts as “space”. For example, some would say that Felix Baumgartner jumped from space and others would say that isn’t quite space. From very low orbits, satellites can make out details as small as the wall. After all, we have Google Maps don’t we? But with the unaided eye and from a spacecraft in orbit? Nope.

It’s not clear where this myth comes from but several 18th century authors mentioned it might be possible to see the Wall from the Moon, since we can see what appear to be lunar canals using telescopes. Regardless of the origin, it’s a myth that doesn’t seem to be going away despite our increasing presence in orbit.

2. Gun silencers are a thing

Image: Sherdog/RerouteToRemain

You know that part in the movie when the spy is secretly entering the enemy headquarters and attaches the “silencer” to their pistol? Yeah, that’s garbage. Or at least the supposed effectiveness is nonsense. In the real world, these things are called suppressors and they don’t do as good a job as you might expect. They reduce the volume of the gunshot but usually not low enough to make the gun safe to use without ear protection. If the shot is still loud enough to cause hearing damage to the user, do you think it will help when running through the villain’s headquarters?

Even with small pistols, a suppressor usually brings the noise down to around 160 decibels or more. That’s more than the 140 dB that causes instant hearing damage. Hell, it’s more than a jet plane taking off. Surely the evil soldiers James Bond is hiding from would hear something as loud as a jet plane going off in their headquarters.

3. Sharks don’t get cancer

Image: simpsonsworld.com/FX Networks

As Karl Pilkington once said, “I never heard of a cod being ill”. How many times have you seen a shark with cancer? Never? Well that proves it, right? After all, all sharks spend all their time at the surface of the ocean and near humans, right? And when they die they definitely don’t sink to the bottom of the ocean, right? Absence of evidence is not evidence of absence and in this case there’s direct evidence that sharks do get cancer anyway.

Where does the myth come from? The myth might have originated from real studies suggesting that sharks have lower rates of disease than expected. However, the main culprit behind the belief going mainstream is Dr William Lane who wrote the book Sharks Don’t Get Cancer based on his own research supposedly finding that sharks can cure their own cancer. It sounds innocent enough if it weren’t for the fact that he started a business selling shark pills to cure cancer. Of course they didn’t work and biologists have found that sharks do get cancer anyway. It’s a myth that needs to die because sharks are often killed in huge numbers for “medicine”.

4. We use only 10% of our brains

Image: giphy/Universal Pictures

Oh did we groan at Morgan Freeman in Lucy. Even more so when it turns out using more than 10% of your brain allows you to manipulate the fabric of reality. It doesn’t really matter how you choose to measure this 10%, it just isn’t true. Using brain scans it’s possible to see where the brain is active during various tasks. We see more activity in some regions than others during specific actions but ultimately we use the entire brain. If we remove even small chunks of the brain, it can be devastating. Brain injuries never seem to happen to that unimportant 90% that we don’t use!

It’s also helpful to think about this from an evolutionary perspective. The brain is energetically expensive. It burns a lot of fuel, even when you sleep. Your brain is just 2% of your bodyweight but it uses about 25% of the oxygen your body needs. If a whole chunk of it has no purpose, it’s surprising that natural selection hasn’t worked its magic and reduced it over generations. But none of this matters because we can clearly see that the whole brain is used. It’s a myth that people love because it allows them to come up with explanations for supposed psychics and mediums. Or make crap Scarlett Johansson movies.

5. Red makes bulls angry

Image: Boston Dyanamics

You’ve probably seen matadors beckoning angry bulls with a red cape. The idea that red makes bulls angry is so common that we use it in cartoons, where characters frequently fool bull characters by painting something else red to get their attention and distract them. That wouldn’t work in real life because red doesn’t make bulls angry. We know it’s a myth for many reasons but the most important is that bulls can’t even see red, they’re colour blind to that part of the spectrum.

So why do bulls charge at matadors? Firstly they’re usually angry to begin with. It’s a disgusting sport. Next, it’s the taunting movements that attract the bull to charge. There was an episode of Mythbusters where they showed various coloured flags and the bull never reacted in a way that suggested it was angered by the colour red. Instead, it was the waving movement of the flags that caused the bull to charge.

6. There’s no dark side of the moon

Image: NASA

Many people have a poor understanding of what the Earth, Moon, and Sun are actually doing in space. Some people think the seasons are caused by us moving closer to or further from the Sun rather than it being axial tilt. Similarly, a poor understanding of how the Moon orbits our planet leads to the myth that there’s a dark side of the Moon that’s always cold because light never touches it. Pink Floyd probably didn’t help.

We always see the same face of the moon because of tidal locking, which means there’s a far side of the moon. But this has no effect on light reaching that side. The moon is spinning but it takes about as long to spin once as it does to orbit the Earth, so we see almost the same face all the time. But that’s no reason to think one side gets no sunlight.

Think about the Sun’s light hitting the Earth. Half of the planet is always receiving light and the other half is shrouded in darkness. That’s the difference between night and day. As we spin through space, the Sun’s light reaches different parts of the globe but always covers about 50% of it.

Except for when there’s a lunar eclipse, it’s the same situation for the Moon; there’s always about 50% of the surface receiving sunlight. When we see a full moon, the side facing us is lit up and the far side truly is the dark side. But when we see the moon as a crescent, that’s because we’re seeing a portion of the moon that is lit with some of the far side being bathed in sunlight too. When the moon is between the Sun and Earth, the far side is the brightest side. So there is no dark side, just a far side.

7. Chewing gum takes years to be digested

Image: giphy/Warner Bros. Pictures

Did your parents warn you not to swallow chewing gum because it takes almost a decade to pass through your digestive system? They were wrong but it was still good advice. We’re unable to digest chewing gum full-stop since it’s mostly a synthetic rubber. We make use of a few ingredients like the flavourings but we can’t break down the rubber so it gets sent out about as quick as anything else.

It turns out synthetic rubber isn’t something you should be swallowing, so your parents were definitely onto something. Usually chewing gum passes through without incident but it can get stuck occasionally and cause blockages. If it gets stuck to anything hard in your stomach, it can pull those items through the intestines and causes damage. It won’t take years to digest, but it’s a good idea to spit out rubber once you’re done chewing it.

8. Lightning never hits the same place twice

Image: WordPress/clio44

This myth is so common that we use it to make people feel better when bad things happen to them. At least it won’t happen again, lightning doesn’t hit twice. There’s nothing special about lightning that means it cares about avoiding where previous lightning strikes have gone before. More plausible is that the surface of the Earth is so large that it’s statistically impossible that lightning would hit the same spot twice but that’s demonstrably false.

Lightning strikes are more common in some places than others. The lightning capitol of the world is Lake Maracaibo in Venzuela. NASA’s Tropical Rainfall Measurement Mission used a Lightning Imaging Sensor ad found that the lake has an average of about 600 strikes per year per square mile. Besides, a fork of lightning is searching for the fastest way down and tends to hit buildings and trees with regularity. Skyscrapers use lightning rods because some are hit hundreds of times per year. In some ways, it’s very likely that lightning will strike the same place twice.

9. Sugar makes kids hyper

Image: simpsonsworld.com/FX Networks

Uh oh, that child you’re babysitting is annoying at the best of times and now someone has given them a ton of sugar. Chances are they’re going to be hyperactive for a while but it isn’t because of the sugar itself. There’s no evidence that sugar makes kids hyper. Instead it seems to be psychological and caused by other factors in the environment. It’s easy to imagine kids at a birthday party going bananas with their friends while downing sweets and juice. Their hyperactive behaviour seems to be tied to being around friends and the excitement of a party rather than the sugar itself.

The fact that this myth is commonly believed by so many people might make it worse. It turns out that parents who believe in the link see their children as more hyperactive even when others don’t. To be fair, we get pretty excited at the very prospect of getting sugary treats. Om nom.

10. Humans have abnormally large brains

Image: giphy.com/BBC

We’re the centre of the universe. We’re designed in God’s image. We play, we build things, we use tools, we have sex for fun… we’re utterly unique and modest. We’re also pretty good at sarcasm. What sets us apart from the other animals? The answer is not much, really. If you have to pick one thing it’s probably how complex our language capabilities are. Among all these myths about our uniqueness, the most common is the idea that our brain is relatively huge compared to the size of our body.

Are human brains bigger than the average we would expect for our size? Yes, absolutely. But we’re not alone. Our brain isn’t much bigger relative to our body when compared with dolphins and mice. Indeed, some animals have bigger brains compared to the size of their bodies. Just look at the super intelligent birds! What seems to be more important is what we’re actually doing with the brain. Our cerebral cortex is relatively bigger compared to other mammals and helps make us different. But overall size? It’s not that exceptional. We’re on the larger end of the spectrum for primates but it scales normally with other mammals.

Main image: Albert Kok, distributed under a CC-SA 3.0 license