Modern Science has its own set of myths and legends.
There is no gravity in space: Blame the term "zero-gravity"
for this common misconception. Gravity is everywhere, even in space. Astronauts look weightless because they are in continuous freefall towards the Earth, staying aloft because of their horizontal motion. The effect of gravity diminishes with distance, but it never truly goes away.
Humans use only 10 percent of their brains
However popular this theory is, scientific studies have shown that it is not true. MRI imaging clearly demonstrates that humans put most of their cerebral cortex to good use, even while dozing.
A coin dropped from the top of a tall building could kill a pedestrian
A coin is not the most dangerous of aerodynamic weapons. A combination of its shape and wind friction means that, tossed even from the 1,250-foot Empire State Building, it would travel fast enough, merely, to sting an unlucky pedestrian.
Animals can predict natural disasters
There is no evidence that animals possess a mysterious sixth-sense allowing them to predict natural disasters. Their keen senses of smell, hearing, and sharp instincts alone are enough to send them scattering for the hillsides during a hurricane or tsunami. And even so, animals often die during natural disasters, so if they do have some sort of sixth sense, it's not worth much.
Adults don't grow new brain cells
Much of a human's crucial brain development happens during childhood, but it isn't all downhill from there. Studies have shown that neurons continue to grow and change well into the adult years.
Water drains backwards in the Southern Hemisphere due to the Earth's rotation. Water flows down the plug-hole in the direction it is introduced into a sink or drain. The effect of the Coriolis (when the rotating earth causes the winds to deflect to the right in the northern hemisphere and the left south of the equator) is too weak to affect a system as short-lived as a basin full of water.
You get less wet by running in the rain
Actual mathematical equations devoted to this popular question have suggested it is true, though not for the simple reasons one might think. Complexities include factoring in the number of rain drops hitting the walker's head versus smacking the runner's chest.
The Great Wall of China is the only manmade structure visible from space
There are several variations on this folkloric statement, and they're all quantifiably false. Astronauts can spot the Great Wall from low-Earth orbit, along many other structures such as the Giza pyramids and even airport runways. But the Great Wall of China is not visible from space.
It takes seven years to digest gum
While it may prove a bit more difficult to break down than organic foodstuffs, chewing gum gets no special treatment from the digestive system. Doctors figure this old wives' tale was invented to prevent kids from swallowing the rubbery substance.
Hair and fingernails continue to grow after death
Though hair and fingernails appear to keep growing after death, this is merely a morbid optical illusion at work. In death the human body dehydrates severely, retracting enough skin to expose more nail and hair.