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List of common misconceptions

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This article contains weasel words: vague phrasing that often accompanies biased or unverifiable information. Such statements should be clarified or removed.

This is a list of uncontroversial, undisputed clarifications to common misconceptions.

Note: Many of these misconceptions can also be found in the articles Urban Legend, Old wives' tale and Conventional wisdom
This list is incomplete; you can help by adding missing items.

Geography

  • Mount Everest is, indisputably, the highest point of land above sea level (8850 meters / 29035 feet) which, according to traditional measurements, means that it is the tallest mountain in the world. Given certain definitions, however, this can be challenged. One alternative method of measurement is the base-summit height. When this is applied, Mauna Kea a dormant volcano in Hawaii turns out to be much higher at 10,314 meters (33,480 feet). This takes into account Mauna Kea's base on the ocean floor, some 6000m below sea level. Its height above sea level is only 4,208 m (13,796 ft). If the base-summit height is measured from land only, Mount Kilimanjaro may be the tallest above-ground and above-water (or "free-standing") mountain in the world, measured from its base (at ground level) to the summit at 5,896 meters (19,344 feet). Another alternative method is to work out the furthest point of land as measured from the centre of the earth. Two peaks - Chimborazo, a volcano in Ecuador, and Huascarán, a mountain in Peru - vie for this position, which is a result of the Earth "bulging" at the equator. Both of these peaks are 2.1km "taller" than Everest.

History

  • Some believe that Christopher Columbus had a hard time receiving support because Europeans believed in a flat Earth. In fact, sailors and navigators of the time knew that the Earth was spherical, but (correctly) disagreed with Columbus's estimates of the distance to the Indies. If the Americas did not exist, and Columbus had continued to the Indies (even putting aside the threat of mutiny he was under) he would not have survived long enough to reach them.
  • While scarcely a success, the Charge of the Light Brigade was not a complete loss — more than half the cavalrymen who began the charge finished it unwounded.
  • Napoleon Bonaparte was not especially short. After his death in 1821, the French emperor's height was recorded as 5 feet 2 inches in French feet. This corresponds to 5 feet 6.5 inches in Imperial (British) feet, or 1.686 metres, making him slightly taller than an average Frenchman of the 19th century . The metric system was introduced during his lifetime, so it was natural that he would be measured in feet and inches for much of his life. A French inch was 2.71 centimetres , an Imperial inch is 2.54 centimetres. In addition to this miscalculation, his nickname, 'le petit caporal', adds to the confusion, as non-francophones mistakenly take petit literally as meaning "small"; in fact, it is an affectionate term reflecting on his camaraderie with ordinary soldiers. He also surrounded himself with soldiers, his elite guard, who were always six feet tall or more.
  • During World War II, King Christian X of Denmark did not thwart Nazi attempts to identify Jews by wearing a yellow star himself. Jews in Denmark were never forced to wear the Star of David. The Danish government did help most Jews flee the country before the end of the war .
  • Italian dictator Benito Mussolini did not make the trains run on time. Much of the repair work had been performed before Mussolini and the fascists came to power in 1922. Accounts from the era also suggest that the Italian railways' legendary adherence to timetables was more myth than reality .

Life

Animals

  • Warts on human skin are caused by viruses that are unique to humans (Human papillomavirus). Warts cannot be caused by proximity to, or contact with, toads. (Nevertheless, people should avoid touching frogs or toads, as some of them secrete poison through glands.)
  • Dragonflies do not have stingers, and do not usually bite people (though they will bite in order to escape, for example, if grasped by the abdomen).
  • Porcupines CANNOT shoot their quills out of their bodies by flexing various muscles. The quills are like sharp hairs, not missiles, and would require some similar firing method in order to work. If the animal could force the quills out by flexing, they would simply fall out like regular hair.
  • Bats use echolocation to navigate whilst flying in darkness. Bats are not "blind", however. Their eyes are small and poorly developed, but they are still capable of sight, particularily long-range.

Entertainment

Main article: List of famous misquotations

Food and drink

Main article: List of misleading food names

Actually, a lot of foods with country-names are different in various countries. For example, "Chinese" is added to checkers and jump rope, and "French" is added to dressing and fried potato sticks in the USA, but in other countries the very same items can have different country's names—or no country names—attached to them. The custom has origins in a perception that some goods--and some country names, which can change through time, as well—are exotic, or in a desire to market them as such.


Science

Astronomy

  • The seasons are also not the same length. Due to the earth moving fastest in its orbit when closest to the Sun, the southern summer / northern winter is the shortest season, with northern summer / southern winter being the longest. However, the difference on earth is only a matter of a few days, while on Mars with its more eccentric orbit the difference is more distinct. This depends upon the definition of season that is used, which is different, for instance, in geography than it is in astronomy, which may be different than it is defined on the calendar, which has fixed seasons.
  • In fact, the seasons simply do not exist in any meaningful way, other than as a human social convention. There is no global agreement on when the seasons begin and end, or indeed how many of them there are.
  • While in a low orbit, a viewer can see the Great Wall of China from space, but it is not unique in that regard. From a low orbit of the earth, many artificial objects are visible on the earth, not just the Great Wall of China: highways, ships in the sea, dams, railroads, cities, fields of crops, and even some individual buildings. As to the claim that it is the only man-made object visible from the moon, Apollo astronauts have reported that they could not see any man-made object from the moon, not even the Great Wall.
  • There are two possible candidates for the third 'biggest' planet in our solar system. It may be either Uranus and Neptune, depending upon whether bigness is defined by volume or mass: Uranus is the greater in volume (63 Earth volumes against 58), while Neptune is the greater in mass (17 Earth masses against 15).
  • The "dark side" of the Moon spoken of by NASA refers to the "far side" of the moon, where radio transmission would not be possible for the mission (and to the overlapping current dark side, where temperature and light may be too low to support the mission, not a permanent one as is commonly believed). The Moon is in synchronous orbit--that is, it takes exactly the same time to rotate once around its axis as it does to make one orbit around the Earth--so it has a far side, because it always keeps the same hemisphere pointed towards Earth. When the Moon is roughly between the Sun and Earth, it is daytime for the "far side" and night time for the "near side". When the Moon gets "behind" the Earth, it is night time for the "far side" and daytime for the "near side". Once each synodic month, the near side of the Moon is indeed largely illuminated by the Sun. At this time, we are able to see most of the area of the near side, resulting in a full moon.
  • The gravity of a black hole is slightly weaker than, not stronger than, the gravity of the star which formed it, outside the Schwarzschild radius. Isaac Newton's laws of gravitation state that, for an object with a spherically-symmetric distribution of mass, two things affect how much gravitational force is felt: mass of the object and distance to the object's centre. A black hole has slightly less mass than the star which formed it, because when stars go supernova, some of the star's mass is converted into energy according to Einstein's equation E = mc², and a great deal of the star's mass is returned to the interstellar medium. The actual black hole is caused by a singularity. Only when a distance of (slightly less than) the star's original radius is passed does gravity become greater. Once the event horizon is passed the speed required to escape the black hole's gravity exceeds that of light. As such, black holes are not similar to "cosmic vacuum cleaners". Objects will settle into stable orbits around them just like they would around any other mass in space.
  • When a meteor lands on Earth (termed a meteorite), it is not usually hot. Small meteorites are not hot when they fall to Earth — in fact, many are found with frost on them. A meteorite has been in the near absolute zero temperature of space for billions of years, so the interior of it is very cold. A meteor's great speed is enough to melt its outside layer, but any molten material will be quickly blown off (ablated), and the interior of the meteor does not have time to heat up because rocks are poor conductors of heat. Also, atmospheric drag can slow small meteors to terminal velocity by the time they hit the ground, giving them time to cool down (Plaitt 2002:137-38).

Meteorology

  • It is incorrectly believed that clouds form in warm air because cold air "holds" less water vapor than warm air. It is the heat of the water itself (and the relative heat of its surroundings) that causes humidity, condensation and clouds to form.
  • A misconception embraced by Hollywood is that air aloft will retain its cold temperature when it hits the ground if it descends "too fast to warm up". This is what is portrayed in The Day After Tomorrow when the outflow from a column of rapidly subsiding stratospheric air chases the protagonists down the hallway of the library flash freezing everything in its path. This kind of rapid descent does in fact happen (albeit not originating in the lower stratosphere), but the resulting effect when it hits the ground is not a rapid decrease in temperature, but a rapid increase in temperature. This is because of adiabatic warming and the fact that potential temperature is approximately conserved. (See heat burst for a better description.)

Health

  • People do not use only ten percent of their brains. The origins of the myth are not clear, it is probably the result of misunderstood or misinterpreted legitimate scientific findings as well as self-help gurus .
  • Contrary to popular understanding that different tastes map to different areas of the tongue, taste qualities are found in all areas of the tongue.. The original "tongue map" was based on a mistranslation by a Harvard psychologist of a German paper that was written in 1901 . Sensitivity to all tastes occurs across the whole tongue and indeed to other regions of the mouth where there are taste buds (epiglottis, soft palate).


Physics

  • It is widely believed that the water from draining bathtubs spins in a certain direction due to the Coriolis effect: it does not. The Coriolis effect over something as small as a bathtub is negligible. About the only things are affected by Coriolis effect from the Earth's rotation are air flight, long-range missiles, and weather systems.
  • A common misconception about wings and lifting force is widespread among textbooks, reference books, and even appears in pilot training materials. The incorrect explanation is known as the "equal transit time fallacy." While it is true that the air travelling above a tilted (or cambered) airfoil is moving much faster than the air which travels below, many references incorrectly explain the reason. They say that the divided parcels of air must race to meet each other at the trailing edge of the airfoil, and because the upper surface of the airfoil is longer, hence the upper parcel must travel faster to meet the lower parcel. This is wrong. In reality the path-length is irrelevant and a thin fabric wing (or an upside down wing) works fine. This is because the upper and lower parcels never actually meet. The parcel of air above the wing greatly outraces the lower one, and they remain divided after the wing has passed by. This speed-difference occurs because the trailing edge of the airfoil forces air to flow downwards, then air above the airfoil rushes in to fill the space vacated by the downward-deflected air. At the same time, the air below the airfoil slows down to make room for the downward-deflected air. The position of the trailing edge thus creates "circulation" in the chordwise direction. The "longer surface" of the top of an airplane wing is not critical to produce lift, so any wing can produce some lift if its rear half can cause a large flow of air to move downward relative to the direction of air approaching the wing (in the case of passenger aircraft, one reason for making a thick wing is to allow placing fuel tanks inside it). Hang gliders are able to produce lift despite having a wing with little thickness, which thus has almost the same surface shape on the top and bottom.
  • Many textbooks claim that electricity within wires flows at nearly (or even exactly at) the speed of light. This causes many people to become confused and assume that electrons themselves move almost instantly through the circuit. In fact it is the electrical energy which flows almost at the speed of light. Electrons, which have mass, can never travel at the speed of light as explained by the theory of relativity; moreover, not even the energy can travel at the absolute speed of light unless the metal conductors are immersed in vacuum. The drift velocity of the charges (electrons) in an electric current is extremely slow in human terms, on the order of centimeters per hour (rather than the millions of meters per second of the speed of light). Where the electric current is visible, as in electrophoresis, the slow movement of brightly colored charge carriers can be seen directly. Imagine a hose which is full of water but is initially not flowing water: when water is introduced into the hose at one end, it takes a while for the introduced water molecules to transit the entire hose, yet water already in the hose begins coming out of the opposite end immediately. The pressure wave transits the hose very quickly, analogous to the voltage on a wire, but the water molecules themselves transit the hose much more slowly, analogous to the flow of electrons in the wire. In alternating current, as used in wall outlets, the direction of current is alternated rapidly (such as 60 times per second), and in this case, the electrons stay in about the same place the entire time, staying in the same place on the filament inside the light bulb, for instance, while vibrating back and forth over a very small distance.
  • Some believe that the sky looks blue because it reflects the ocean. The sky actually looks blue because shorter wavelengths are scattered more easily by Earth's atmosphere than longer wavelengths, and blue is a short wavelength in the visible spectrum. This phenomenon is referred to as Rayleigh Scattering.
  • Many believe that lakes and oceans are blue only because they reflect the blue sky. Actually water looks blue because water is blue; the water molecules do absorb some light, and they absorb red frequencies more than blue. The effect is small, so the blue color only becomes obvious when observing layers of water many meters (or more) thick. (This effect is noticeable to a lesser amount in white-painted swimming pools.) In salt water or mineral-laden fresh water, the color of dissolved minerals can also be seen. Sky-reflection does play a role, but only when the water surface is very calm, and only when the water is observed at a glancing angle less than approximately ten degrees.
  • It is often claimed that astronauts in orbiting spacecraft are in "zero gravity." In reality they are falling along with the spacecraft. Because gravity in a free-fall environment is not easily detected, conditions of free-fall will simulate a "zero-gravity" environment. NASA refers to these conditions as microgravity. Earth's gravitational effects are very strong at the low orbit altitudes used by the Shuttle (about 85% of gravity at Earth's surface), and of course there are also the effects of other planets and the Sun. Gravity falls off rapidly as one leaves the Earth's surface, but one can never completely escape the gravitational pull of the Earth (or any other mass in the universe) even at vast distances, though the effect may be negligible. "Zero gravity", therefore, should be applied to gravity far from any planet only if units are specified and the magnitude is measured less than 0.5. If the gravity is less than 0.005 than the gravity on the Earth's surface then it can be called "zero percent gravity" but it is not "absolute" zero gravity. A free-fall situation can be more properly called "simulated zero-gravity" since the free-falling bodies are actually under a strong gravitational pull through their orbits. Simulated zero gravity can be experienced in any near freefall situation, including extremely fast elevators (but only simulated reduced gravity), the "Free fall" ride at Six Flags amusement park in Los Angeles, CA, USA (more so), or in skydiving (near-real simulation for a short time). Astronauts use the inside of free-falling airplanes for training (see Vomit Comet). A coin placed in front of the face in these situations and lightly pushed will appear to float across towards a friend standing nearby (or to fall very slowly).
  • The magnetic pole near Antarctica is usually called the "south magnetic pole," but according to the physics and engineering standard definition of magnetic polarity, this is wrong. Since magnetic poles are attracted to their opposites, and since a compass needle is a magnet marked N on its end having standardized "North" polarity, the compass points to the magnetic south pole of the Earth. Therefore, the Antarctic pole is a north-type pole, while the magnetic pole under the Arctic ocean is a south pole. (However, the poles have flipped in past, with the last pole reversal being the Brunhes-Matuyama reversal of 780,000 years ago.) The problem stems from multiple definitions in the sciences, and, actually, there are multiple poles: geographic versus magnetic. In astronomy, the geographic north and south poles of a planet are defined by the direction of rotation (thus Earth's north and south poles). Earth also has more than one set of magnetic poles--a strong overall dipole which is superposed on a weaker quadrupole. Not only have the magnetic poles moved to opposite geographic poles in the past, but they also drift around more or less randomly, according to the movement of molten iron in the Earth's core.
  • Due to Archimedes's principle, it is the melting of glaciers, and not the melting of sea ice or floating icebergs that raises sea levels. The predicted threat is due to the disattachment or melting of inland ice like on Greenland and in Antarctica, in addition to the increase in volume resulting from the thermal expansion of water.
  • A Crookes radiometer or "light-mill" of the type often sold to the public does not turn by radiation pressure, as they may be claimed to. In fact, it turns in the opposite direction which one would expect due to radiation pressure. The correct explanation is essentially that molecules of gas in the partial vacuum inside rebound from the vanes of the radiometer transmitting a different force depending on the temperature of the gas (harder on the black, hotter side of the vanes). See the Crookes radiometer article for further detail.

Evolution

  • Evolution does not attempt to address the question of the origin of life: for that, see abiogenesis. The two are commonly conflated.
  • Evolution is not a random process but one guided by the process of natural selection. A common misconception is that the absence of conscious intervention means that the process becomes random.
  • Random mutation of genes can however play a part. There is some debate on how large a part, but it really doesn't matter so long as every time two members of a population combine their genes, the combined gene of their offspring is unique: which we can see to be the case in reality, except in the case of identical twins.
  • Evolution does not need to be directed. It may not be accidental or random, but it's also not directed. It's a process, like bouncing a ball, or generating a fractal, that appears to create an intelligent pattern, but which on inspection is very simple.
  • Humans never evolved from chimpanzees instead they share a common ancestor known as Sahelanthropus tchadensis that existed around 7 Ma in the late Miocene epoch.
  • Evolution says nothing about cosmology, the big bang, or where the universe, galaxy, solar system, or earth came from. Evolution is only about life.
  • Evolution does not need to be slow. Millions of years are not required to see evolution, or even speciation in action.
  • Evolution does not happen within a single creature: a chimp can't be born a chimp and turn into a gorilla. You need at least one generation to observe evolution. To be provable evolution, you need quite a few generations, in order to establish that the changes remain in subsequent generations, though.
  • Evolution does not happen within just one creature: you need the entirety of a population to observe evolution. You need some of them to breed, and some not to.
  • Evolution does not require an increase in complexity. A population can evolve to become simpler, and have a shorter genome - often called "devolve", but that's a misnomer.
  • Evolution is not progress from "lower" to "higher". In that sense, "Evolution" is a misnomer.
  • Evolution does posit "transitional forms"... but not "endpoint forms". That is, every animal, plant, fossil that exists, is an example of a transitional form. Evolution is a constant process.
  • When people say "transitional forms" they generally mean "a common ancestor for two populations": of which there are mmany.
  • Evolution has been observed, countless times, in and out of the laboratory.
  • Evolution does not violate the 2nd law of thermodynamics.
  • Evolution has been proved: it is a "theory" in the same way as the theories of gravity, thermodynamics, etc.
  • Evolution does not claim that phenotypic changes (changes caused by the environment, such as larger size due to better diet, amputations, etc) can be passed from generation to generation.

Religion

Christianity

  • The term Immaculate Conception does not refer to Jesus being conceived within Mary through the holy Spirit and without sexual intercourse, but rather to the Roman Catholic teaching that Mary herself was conceived without the stain of Original Sin.
  • The word "Prodigal" in The Prodigal Son does not mean one who travels (or, alternately, one who travels and then returns). "Prodigal" is characterized by a profuse and/or wasteful expenditure. The Prodigal Son of the story was just this when he wasted all of the money he obtained from his father and had to work as a lowly pig-tender until he finally recounted his losses and went back to his home.
  • Nowhere in the Bible is Mary Magdalene ever referred to as a prostitute. Before her seeing of the risen Jesus, the only other mention besides the listing of her name is the mentioning in Luke 8:2 that she had been possessed by seven demons.
  • The number of Biblical Magi who visited Jesus is never specified, only that they carried 3 gifts. Additionally, they are never referred to as "kings." In addition, whilst they were said to have been informed of the birth of Jesus by the appearance of a new star, there is no textual evidence to suggest they followed it.

Technology

  • Thomas Crapper did not invent the flush toilet, Thomas Edison did not invent the light bulb, and Henry Ford did not invent the automobile or the internal combustion engine. In all 3 cases, their contributions were in the area of improving and popularizing the devices in question. Ford did introduce the assembly line, and used it to bring the cost of automobiles into reach of many more people.

Transportation

  • Some believe that the ship Mary Celeste was called Marie Celeste. In fact Marie Celeste was the spelling used by Arthur Conan Doyle in a story based on the incident.

See also

References

  • Philip Plait (2002). Bad Astronomy: Misconceptions and Misuses Revealed, from Astrology to the Moon Landing "Hoax". John Wiley & Sons, ISBN 0-471-40976-6.

External links

  1. Huang A. L., et al. ""The cells and logic for mammalian sour taste detection""., Nature, 442. 934 - 938 (2006).
  2. Scenta. "How sour taste buds grow". Retrieved August 28. {{cite web}}: Check date values in: |accessdate= (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help)
  3. Roberts, David. 2002. Signals and Perception. Palgrave MacMillan.
  4. Hänig, D.P., 1901. Zur Psychophysik des Geschmackssinnes. Philosophische Studien, 17: 576-623.
  5. Collings, V.B., 1974. Human Taste Response as a Function of Locus of Stimulation on the Tongue and Soft Palate. Perception & Psychophysics, 16: 169-174.
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