If something gets repeated often enough it eventually becomes "truth."
You may be shocked to read the following list and find some facts you never thought to question aren't actually true.
From the Great Wall of China to the Empire State Building -- the time has come to shed some light on some of the things we thought we knew.
Though the Great Wall is, admittedly, pretty big (it runs for over 1,500 miles), there's no way you can see this structure from space.
You can't even see the Great Wall from low orbit. No astronauts have reported seeing human-made objects from space. Although this statement was probably hyperbole made to explain how enormous the Wall is, the fact remains: you can't see the wall after clearing 180 miles of atmosphere.
On the contrary, it's the little things that you can spot, like city lights at night.
Field trips to the Empire State Building are almost always accompanied by this warning: don't drop a penny off the top. Even a penny can kill a person from here.
A falling penny's terminal velocity maxes out at 50 miles per hour. As seen on the show Mythbusters, a penny won't pick up enough speed to crack a human skull. Wind resistance makes this impossible event even more unlikely. The worst case scenario from a penny dropped from a great height is a slight sting.
This myth, particularly popular among psychics, is widespread and has been used in advertising campaigns and popular culture for years. And while only a small number of our brain's neurons are actively firing at any one moment, that doesn't mean the rest of our brain is just sitting around.
Brain imaging research shows that just about all of our brain is used over the course of a day. Brain function isn't extremely localized: different parts of the brain handle different functions, and this is spread throughout the brain -- there is no 90% of unused gray matter lying around up there.
Some people think that dogs sweat through their tongue -- that when you see them panting, drooling, that's like a human dripping with sweat.
Sight, smell, touch, taste, and hearing: these are not our only senses.
Although scientists disagree on the exact definition and number of senses, some of the others listed include: a sense of balance, acceleration, pain, body position, and relative temperature. There's even senses of time, itching, hunger, and blood carbon dioxide levels, just to name a few -- and there are up to 20.
Drunk co-eds will attest that they are able to walk around in the dead of winter in only a t-shirt or a skirt, provided they keep drinking. Same goes for skiers on the mountain tops.
Sadly, while alcohol may make one feel warmer, drinking actually makes us colder over time.
Alcohol dilates our blood vessels, forcing our blood closer to the surface of our skin and closer to the nerve receptors -- that's the feeling part. The reality sets in when cold air steals this heat, which originally was stored safely in our cores. Hypothermia may ensue.
The matadors of Spain -- and anywhere else, for that matter -- wave red capes in an effort to enrage bulls for entertainment purposes. People have since drawn the conclusion that the color must anger the bull.
But bulls are color blind. Being dichromats, it isn't the color of the cape that bothers them, but the movement of the fabric. This incites the bull to charge.
Skeptics of evolution might say there's no way humans evolved from chimps -- and they would be right.
A misunderstanding of evolutionary theory has given way to the idea that humans came from modern-day primates. Actually, both humans and chimps are said to have evolved from a common ancestor. Millions of years ago, this ancestor split into two separate lineages, eventually becoming apes (like chimps and gorillas) and hominids, the precursor to human beings.
Hence our close relation to, but not evolution from, modern day chimps.
Rumor has it that you can't touch baby birds or eggs that have fallen from the nest, or their mother will reject them as "tainted" by the smell of your human-ness.
While messing with a nest may cause a mother to temporarily flee, this is due to visual cues, not smell. But even so, birds are limited in their olfactory sense and can't differentiate human from bird. Putting a bird or egg back in the nest -- if the bird is supposed to be there -- will not lead to rejection.
People are encouraged to put baby birds back in their nest, when possible.
Somewhere along the way, a rumor was started that hair and nails continue to grow after death -- leading to nightmares worldwide of opened caskets featuring foot-long fingernails and mountains of hair.
Hair and nails only look like they have grown after death. The skin around these areas begins to lose water and shrink, giving the hair and nails the appearance of having grown. The fact is, when you're dead, not much is going to be happening growth-wise.
A 1998 paper by scientist Andrew Wakefield reported a connection between vaccinations and autism in children. The report set off a vaccination scare that lasts to this day.
Since that time, critics have pointed out that the experiment was "a small case series with no controls, linked three common conditions, and relied on parental recall and belief." For whatever reason, Wakefield's work was fraudulent, and the paper was eventually retracted. Subsequent investigations have found no evidence linking autism and the MMR vaccine.
The play Dying Goldfish features a line of dialogue that helps propagate this common myth: "A goldfish has a memory of only thirty seconds, so when it's dying it thinks it's been dying all its life." Some even thought the goldfish memory span to last only several seconds.
In reality, goldfish have a memory span of up to three months. They can be taught to follow a routine and can tell time. Even high school students have gotten in on the action of disproving this myth.
The story goes that touching a toad -- unlike kissing a frog -- can give humans warts.
There are a few problems with this myth, the first being that the bumps on a toad are not warts, they're just bumps. Secondly, humans can only contract warts from the human papillomavirus (HPV), not from animal diseases.
A possible source of this myth is that some toads have poison glands that make humans break out in a rash that looks like warts. But just remember: they're not.
As seen in various films and TV shows, waking a sleepwalker can lead to disastrous (or, depending on the film, hilariously disastrous) results.
But waking a sleepwalker from their dream will leave them momentarily disoriented or confused, that's all. There is no real danger in waking them up. In fact, sleepwalkers can sustain injuries if they continue to walk around. You'll be doing them a favor by shaking them out of it.
People with colds are known to avoid dairy products, like milk, in an effort to decrease their mucus production.
However, there is no scientific evidence to support this idea. It's suggested that this is psychosomatic, as people associate drinking milk with a similar-feeling coating of the tongue and throat.
Men think about sex plenty: according to popular myth, they think about sex every seven seconds. If you tell men that, they might even answer "That sounds about right."
Unfortunately, the closest anyone can get to a real statistic is that men fantasize about sex at least once a day. Then again, maybe only 54% of men do that. Face-to-face sex surveys are unreliable in uncovering the true number, and its not clear if this number will ever be truly quantifiable.
Either way, the seven seconds myth probably overstates the frequency of this event.