Common misconceptions: Things we know that just aren’t so

We all live with misconceptions about the world. This is quite normal. No one can be an expert in everything, so we simplify our learning into easy-to-remember snippets, which are often very close to the truth, but never quite there.

Generally, our misconceptions are insignificant and do little harm. Some times they are very significant and do a lot of harm.

For example, many people believe that when they leave home in winter, they shouldn’t turn off the heat entirely, but rather lower it a few degrees. If they normally maintain a temperature of 20°C (68°F) when at home, when they leave they should turn the thermostat down to about 15°C (59°F). Why? Because they insist that letting the house get very cold when they are away, and then heating it up again when they return, uses up significantly more energy than keeping it at a moderate temperature throughout the day.

I have heard this for years, but never paid much attention to it, largely because when energy prices were low, it didn’t really make much difference. However, we now face severe energy shortages and the potentially devastating effects of climate change. So recently when I heard someone say this, I responded, “As a physicist, I can’t see why this would be true.”

I didn’t insist that the idea was wrong. As a scientist, I know that general principles (“physical laws”) cannot be applied willy-nilly to specific cases, because unknown local conditions might mute their effects or cancel them entirely. I therefore decided to research the issue on the Internet.

No matter how man different key words or combination of key words I tried, I could find no web site that even discussed the idea. Apparently it was either so widely accepted that it didn’t need discussion, or so patently ridiculous that the experts never even considered it. After about a half-hour of fruitless effort, I landed on the site of the United States Department of Energy, who did feel it necessary to comment on the issue (www.eere.energy.gov/erec/factsheets/thermo.html).

Based on years of research, they concluded that “the fuel required to reheat a building to a comfortable temperature is roughly equal to the fuel saved as the building drops to the lower temperature. You save fuel between the time that the temperature stabilizes at the lower level and the next time heat is needed.” In other words, the colder you let your house get when you aren’t there, the more energy you save.

They also dealt with a related misconception. That is, the higher you set the thermostat, the more heat the furnace will put out. Thus, if you want the house to warm up from 15°C to 20°C as rapidly as possible, you should set the thermostat several degrees higher. However, since the furnace will have to work harder, you risk damaging it.

Also not true. “Furnaces put out the same amount of heat no matter how high the thermostat is set. The variable is how long it must stay on to reach the set temperature.”

In short, by turning the heat off completely when you leave the house, you save valuable energy with no damage to the furnace. The big danger lies in not turning it off completely.

As noted earlier, most common misconceptions do little harm. Here are some of my favorite misconceptions. It is up to you to determine how important or insignificant they may be in your own life. If you have doubts, do some research.


Eating at night does not cause weight gain. It is total calories that count. If your body requires 2000 calories a day for normal functioning, then if you take in 2100 calories you will gain weight and if you take in 1900 calories you will lose weight. Many diet plans recommend eating small portions throughout the day to avoid over-eating in the evening, which will almost certainly result in your taking in more calories than your body needs.

Fasting does not help rid the body of toxins. Fasting may give the perception of “cleaning out” impurities, but there is no scientific evidence that this actually happens. It is more a question of mind over stomach.

“Low fat” does not mean low calories. Low-fat foods often have the same or more calories than regular versions, especially for fat-free products. To maintain flavor, fat-free foods often contain add sugar. Read the label.

Olive oil does not have fewer calories than other oils. Like the others, olive oil is 100 percent fat and has essentially the same energy content, about 120 calories per tablespoon. “Light” olive oil refers to the flavor, not the calories.

Fresh vegetables are not necessarily more nutritious than frozen ones. Just-picked vegetables do indeed have more vitamins and minerals, but they gradually lose their nutrients the longer they are stored. Vegetables flash-frozen very soon after picking do not lose their nutrients. So if you prefer fresh vegetables, eat them immediately; otherwise eat frozen.

Searing a cut of meat does not “seal in” its juices; it may actually cause the meat to somewhat dry out. Searing consists of briefly cooking both sides of the meat at a very high temperature, then reducing the temperature to complete the cooking process. Searing meat converts surface sugars and amino acids into a caramelized crust, which enriches its flavor. That is its purpose.


Viking warriors did not wear horned helmets. Horned helmets were used in Celtic religious rituals. Because they could have easily got caught on weapons, such helmets were not suitable for combat.

Christopher Columbus did not try to prove that the world is round. Sailors and navigators of the time already knew that the world was not flat, as did the ancient Greeks. Columbus’s objective was to find a shortcut to India, which turned out to be much farther away than he had calculated. When he landed in the Americas, he labeled the native populations “Indians” because he thought he had reached his goal.

The 13 American colonies did not become independent of Britain in 1776. This was the year the colonies declared their intention to achieve full separation from the mother country. However, the War of Independence (American Revolution), which started in 1775, continued until the signing of the Treaty of Paris in 1783. The United States of America officially came into being as a federal union in 1789.

The words “separation of church and state” do not appear in the American Constitution. The phrase was first used by Thomas Jefferson to reassure religious minorities that they would be protected under the Bill of Rights, the collective name for the first 10 amendments to the Constitution. The First Amendment actually says: “Congress shall make no law respecting an establishment of religion or prohibiting the free exercise thereof.”

Napoleon Bonaparte was not abnormally short. At his death in 1821, his height was recorded as 5 feet 2 inches. However, these were French feet and inches, corresponding to today’s 5 feet 6.5 inches (1.69 meters). Napoleon was in fact slightly taller than an average Frenchman of his time. Most historians believe that his nickname “the little corporal” (le petit caporal) had nothing to do with his height.

King Christian X of Denmark did not wear a yellow Star of David during World War II in defiance of a Nazi edict that his Jewish subjects would have to do so. Jews in Denmark never did wear the Star of David. It is true that the Danes were very active in helping Jews flee the country to avoid persecution and deportation.

Charles Lindbergh was not the first man to fly non-stop across Atlantic Ocean; he was the first man to do it solo. The first non-stop trans-Atlantic flight by a team of aviators was achieved by John Alcock and Arthur Whitten Brown in June 1919. Because of the incredible endurance needed to achieve the feat, Lindbergh’s solo flight in 1927, which lasted 33 hours and 32 minutes, made him an international hero.


The Great Wall of China is not the only man-made object visible from the Moon. According to the Apollo astronauts, who went there between 1969 and 1972, no man-made object is visible from the Moon. The misconception originated from a conjecture by astronomers decades earlier that if any man-made object could be seen from the Moon, it would have to be the Great Wall, but it isn’t true.

The “dark side of the moon” is not dark. All parts of the Moon’s surface are illuminated by the Sun roughly half of the time. The phrase uses the word “dark” in the sense of “unknown” or “obscure”, because the dark side is never visible from Earth.

A meteor is not hot when it lands on Earth. It appears to be burning as it flashes through the night sky only because friction with the atmosphere vaporizes its outer layers of ice. Since its frozen interior does not have time to heat up, when a meteor hits the ground it may even be covered with frost.

Polaris, the North Star, is not the brightest star in the northern hemisphere. Sirius is. Sirius has an “apparent magnitude” of ?1.47 (the lower the number, the brighter the star). Polaris has an apparent magnitude of just 1.97, meaning that nearly 50 other stars outshine it. Polaris is so important because it is almost permanently fixed directly above the north geographic pole, so you can always determine which direction is north by locating it in the night sky.


The human tongue is not divided into four distinct areas of taste (sweet, salty, sour, bitter). Taste buds can detect all these taste components all over the tongue. The original “tongue map” was based on a misinterpretation of a poorly conducted experiment carried out in Germany in 1901.

People do not use only 10 percent of their brain. While it is true that only a small minority of neurons are active at any given time, the inactive neurons also play a role in controlling body functions and intelligence.

Shaving does not cause hair to grow back thicker, coarser, and darker. We get this impression because uncut hair has tapered ends. Freshly cut hair does not tapered ends, making it seem thicker and coarser to the touch. It may appear darker because uncut hair is often bleached by the sun. When cut, the lighter top-layer is removed, revealing the darker layer underneath.

Hair and fingernails do not continue growing after death. When a person dies, the skin dries and shrinks away from the base of hairs and fingernails, giving the appearance of growth.

An exceptionally high proportion of body heat is not lost through the head. Although a poorly conducted military study once claimed that “40 to 45 percent of body heat” is dissipated in this way, more recent studies have shown that loss from the head is completely proportionate to heat lost elsewhere in the body.


Exposure to rain or low temperatures does not increase the likelihood of catching a cold. Colds are caused by a virus; experiments have failed to produce any evidence that short-term exposure increases susceptibility to infection. The rise in the number of colds during winter is more likely to be due behavioral changes, notably increased time spent indoors with people who already have colds.

Humans cannot catch warts from toads or any other animal. The bumps on toads are not warts. Warts on human skin are caused by viruses that are specific to humans only (Human papillomavirus).

Lemmings (a type of small rodent) do not engage in suicidal dives off cliffs when migrating. Occasionally they fall off cliffs when venturing into unknown territory, but this is unintentional.

Bats are not blind. Most use echolocation, a type of sonar, to augment their vision. However, all species of bats have eyes and are perfectly capable of seeing.

An earthworm does not become two worms when cut in half. When cut, only the front half, where the mouth is, will survive; the other half will dry out or starve to death.

It is not true that more than half of all humans who ever lived are alive today. Or at least it is hard to substantiate this claim. Other than biblical references, there is no definite starting point for the human race. Even adopting conservative values for the start of humanity, population experts generally agree that significantly less than half of all the people who have ever lived at currently alive.


Using computers does not damage eyesight. Ophthalmologists say that working on a computer for long periods may cause the eye to tire and give the feeling of eyestrain. But the eye is not damaged.

Eating carrots does not improve eyesight. Carrots are rich in vitamin A, which is essential for sight, but so do many other foods. A well-balanced diet, with or without carrots, generally provides all the vitamin A necessary for good vision.

People with weak eyes should not necessarily avoid reading fine print. The idea that the eye is like a muscle is incorrect; it is more like a camera. A camera does not wear out faster because it is used to photograph small objects.


The theory of evolution does not try to explain the origin of life. It is concerned only with how species have changed over time, and thus presupposes that life already existed.

The theory of evolution does not claim that humans evolved from apes or monkeys. Rather, it says that humans and other simians (chimpanzees, gorillas, orangutans, baboons, etc.) all have a common ancestor that lived some 7 million years ago. In other words, simians are like the branches of a tree, all starting from a single trunk but then going their separate ways.

The theory of evolution does not claim that changes in species must necessarily take millions of years to show their effects. Rapid evolution has been observed many times both in controlled laboratory experiments and in nature.

The theory of evolution does not proclaim “the survival of the fittest”, i.e. certain species are considered to be “strong” are destined to eradicate other species considered to be “weak”. Any species whose members are capable of reproducing themselves before dying is considered to be “fit”. In other words, the species will survive despite any weakness.

In science, the word “theory” does not indicate doubt. On the contrary, it denotes a well-defined set of principles that help explain and make predication about occurrences in the physical world. A hunch or suspicion still to be tested is called a “hypothesis”. Thus, the theory of evolution, theory of gravity, the theory of relativity, and a host of other theories are all considered to have scientific validity.


The blue color of lakes and oceans is not a reflection of the blue sky. When water molecules encounter light, they absorb red frequencies more easily than blue frequencies. Blue is reflected, so this is what we see. Because the effect is small, the blue color becomes evident only when the water is fairly deep. Shallow water appears colorless.

Airplanes flying long distances do not take less time going west-to-east than east-to-west because of the Earth’s rotation. The effect is caused by jet streams and trade winds, which usually flow in an easterly direction.

The belief that there is no gravity in space is not correct. Astronauts float and experience other aspects of weightlessness because they are in orbit. Scientists call this effect “microgravity” or “simulated zero gravity”. A similar sensation is briefly experienced during skydiving and the rapid descent of an elevator. Gravity exists everywhere in the universe, although in some places it may be very slight and difficult to measure.

A “north wind” does not blow north. It is called a north wind because it comes from the north; it actually blows south. The same is true of all other winds. A “south wind” comes from the south and blows north; an “east wind” comes from the east and blows west, etc.

The frequency and intensity of earthquakes are not increasing. At least, the people who study these things say so. What may be true is that their destructive power is increasing because, due to world population growth, more and more people are living and constructing buildings where earthquakes happen.


The Bible does not say that the forbidden fruit eaten by Adam and Eve in the Garden of Eden was an apple. It simple says they ate the “fruit of the tree”. The belief that it was an apple probably comes from the similarity of the Latin words malus = “bad” and malum = “apple”. Moreover, until as late as the 17th century, in English “apple” was a generic term for all kinds of fruits other than berries.

The Bible does not say that Mary Magdalene was a prostitute. In fact, very little is said about her at all. That she was a prostitute is an interpretation made by the sixth century Pope Gregory the First.

The term “immaculate conception” does not refer to the conception of Jesus by the Virgin Mary, but rather to the Roman Catholic teaching that Mary herself was conceived without original sin.

“Allah” does not refer to a Muslim god different from the Christian one. It is simply the Arabic word for God. Arabic-speaking Christians and Jews also refer to God as “Allah”.

The word “jihad” does not mean a “holy war against Christians”, but simply a struggle or striving. One can have an internal jihad, a family jihad, or a religious jihad, which does not necessarily mean doing violence to non-Muslims. Likewise, “crusade” does not mean a “holy war against Muslims”, but a struggle or striving, such as a crusade against child abuse, a crusade against pornography, a crusade against poverty, etc.

A fatwa is not a death sentence issued by a Muslim cleric, but rather an interpretation of Islamic law issued by an Islamic scholar. This popular misconception probably results from the death sentence pronounced in 1989 as a fatwa on author Salman Rushdie, whose book The Satanic Verses was considered to be blasphemous.


Johannes Gutenberg did not invent the printing press with movable type; these were already used in China centuries before. He was the first European to use a press with movable type, which he probably invented without any knowledge of what the Chinese had already done.

Thomas Edison did not invent the electric light; the idea was already well known. What he did invent was a gas-filled bulb that lasted long enough to make electric lighting commercially viable.

Henry Ford did not invent the automobile; rather he invented a method for manufacturing them at dramatically reduced cost. Before Ford, automobiles were only for the rich. Ford made them available to everyone.


The “black box” used to help determine the cause of airplane crashes is not black. It is bright orange to make it easier to find and recover from a crash site.

A black belt is not a sign that the holder has achieved supreme mastery of a martial art. There are several levels of black belts. While a black belt signifies advanced achievement, it is still possible for one holder to be more (or less) proficient than another.

The term “Romance language” is not derived from the word “romance”, meaning a romantic relationship. It derives from the Latin “Romanus,” meaning “Roman”.

Frankenstein was not a monster. Victor Frankenstein was in fact the creator of the monster in the 1818 novel by Mary Shelley. Even the monster wasn’t a monster. As described in the book, he was rather gentle, but forced to ferociously defend himself against people who attacked him because of his frightening appearance.

A cold nose does not signify that a dog is healthy. Dogs frequently lick their nose, which why it is wet. Evaporation of this moisture in turn makes the nose cold. Thus, a dog sick with fever can still have a cold, wet nose.

Biographical Information

Philip Yaffe has more than 40 years of experience in journalism and marketing communication. At various points in his career, he has been a teacher of journalism, a reporter/feature writer with The Wall Street Journal, an account executive with a major international press relations agency, European marketing communication director with two major international companies, and a founding partner of a marketing communication agency in Brussels, Belgium, where he has lived since 1974. He is author of The Gettysburg Approach to Writing & Speaking like a Professional. Contact: [email protected] or [email protected].

The material in this press release comes from the originating research organization. Content may be edited for style and length. Want more? Sign up for our daily email.

7 thoughts on “Common misconceptions: Things we know that just aren’t so”

  1. The list is endless. It makes you realise that if an idea has been around for a while, it takes a lot of efforts for scientists to be able to challenge it!

    – Raymond

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