1. You’re never far from a rat in London. Via hawaii.edu THE MYTH: Green-eyed, slimy-bellied rodents lurk within six feet of you, wherever you are in the capital.THE TRUTH: It's estimated that the U.K. hosts 3.1 million rats in its urban areas. So even if they decided to spread out as widely as possible just to freak us out, there’d still be only one rat every 5,000 square metres in London. Until that day comes, you’re actually a good 164 feet from one. 2. Cracking your knuckles gives you arthritis. Via kuwaitiful.com THE MYTH: People who crack their knuckles are slowly twisting their hands into hideous wizened claws.THE TRUTH: Multiple studies have found no link whatsoever between the annoying habit and arthritis. The cracking sound isn’t bones being mangled out of shape but the release of pockets of gas from between joints. That said, long periods of knuckle cracking may contribute toward lower grip strength. So pack it in. 3. You can see the Great Wall of China from space. Via avoision.com THE MYTH: From the cold nothingness of outer space, the only visible evidence of mankind is China’s huge wall — which can even be viewed from the moon.THE TRUTH: Even from the relatively low orbit of the International Space Station — about 173 miles above sea level — the Great Wall is impossible to make out. From the moon? Forget about it. This decades-old myth occurs in old school textbooks but was actually disproven by one of China’s own astronauts, Yang Liwei. You can, however, see the pyramids from space. If you squint a bit. 4. Toilet doors are dangerous. Via media-cdn.tripadvisor.com THE MYTH: Touch a door handle on the way out of a public toilet and you might as well have eaten a germ sandwich.THE TRUTH: Door handles have the least bacteria of any surface in the room, according to a test carried out at the University of Arizona. Even though a fairly disgusting 32% of people don’t wash their hands after relieving themselves, to pick up something like salmonella from the germs they leave behind on the handle would require a huge dose. Coupled with the fact that most bacteria need a warm, moist environment to survive and can only live on hard, dry surfaces for a couple of hours, you’re pretty much in the clear. 5. Fish have short memories. Via blogs.telegraph.co.uk THE MYTH: Like a 4 a.m. drunk trying to order a KFC, your goldfish swims around its bowl in a perpetual state of confused awe, its tiny brain resetting the world every four seconds.THE TRUTH: Fish are smarter than you think. Researchers from the Institute of Technology in Israel trained young fish to associate a sound played through a loudspeaker with feeding time. Each time they played a particular sound, the fish would return for food. Up to five months later, they responded in the same way. Meaning for your goldfish, life is even more tedious than you imagined. 6. Chewing gum stays in your body. Via images.wikia.com THE MYTH: Accidentally swallow a chunk of Wrigley’s and your gastrointestinal tract will be wrestling with it for more than half a year.THE TRUTH: Pediatric gastroenterologist David Milov of Nemours Children's Clinic in Florida told Scientific American that this is 100% poppycock. "That would mean that every single person who ever swallowed gum within the last seven years would have evidence of the gum in the digestive tract," he said. “But colonoscopies and capsule endoscopy procedures turn up no such evidence.” In reality, it’ll hang around for about a week. 7. A duck’s quack doesn’t echo. Via norahastrologer.com THE MYTH: That the croak of the humble duck defies the laws of physics by not echoing. And no one knows why.THE TRUTH: It just does. So there. To test the theory, grab a duck, take it to a tunnel somewhere and start up a conversation. Then apologise and take it back. 8. Nails and hair continue to grow after you die. Via 10hairstylesformen.com THE MYTH: As though corpses weren’t disturbing enough, we all turn into Stig of the Dump in death.THE TRUTH: From the moment you’re dead, your hair and fingernails decay with the rest of you. This myth comes from the fact that skin recedes from a dead body, making nails and hair appear longer. 9. Hats keep in heat. Via en.wikipedia.org THE MYTH: You lose so much heat through your head that you’d be better off stark bollock naked with a giant fez on than fully clothed without a hat when it snows.THE TRUTH: Your mum meant well when she told you 40 to 45% of your body heat escapes out of your head like a boiled kettle. But she was lying. The myth began with a U.S. military study in the late 1950s in which soilders were outside in extreme cold covered up everywhere except on their heads. But a 2006 study discovered that in normal circumstances, children only let out about 10% of their body heat from their noggin. 10. A coin thrown off the Empire State Building could kill someone. Via upload.wikimedia.org THE MYTH: Left to gravity, a falling penny will turn into a white-hot meteorite that will sear through a human skull like butter.THE TRUTH: Because it only weighs about a gram and would tumble as it fell through the air, a coin wouldn’t actually gather that much speed. It would hurt a bit if it hit you on the head — but it’s not going to kill you. 11. The five-second rule. Via them-apples.co.uk THE MYTH: Drop a biscuit or a piece of toast on the floor, and bacteria will respectfully observe a five second waiting period before it gets down to business.THE TRUTH: Floors are generally filthy. Salmonella, for example, can lurk in the cracks between tiles for weeks — even if you’ve mopped up recently. You could retrieve your morsel in a tenth of second and it wouldn’t make a blind bit of difference.