all posts Big Think

Why is the Marathon distance 42,195 meters rather than exactly 42 or 43 kilometers? According to legend, a courier ran from Marathon to Athens (more than 30 km in a straight line) with the news of the Greeks' victory over the Persians in 490 BC. At the Olympics in Greece in 1896 the route from Marathon to Athens was a longer road (40 km). At the IV Olympics (Great Britain, 1908) it was decided to start the marathon race at the Royal Castle in Windsor and finish in London at the Great Stadium in front of the Royal Lodge. The route of exactly 26 miles (41,843 m) from Windsor Castle fell short of the Lodge by 385 yards (352 m), and they were added to the route. It was not until 1921 that the International Athletics Federation decided that the course should always be exactly 42,195 m (352 m) long, as it was in London.

Why does the skin renew itself, but the tattoos remain? They're too deep. The top layer of skin, the epidermis, regenerates in a couple of weeks. Its lower layers divide to form keratinocytes, which then slough off and new ones grow underneath. The dye that has penetrated the epidermis exfoliates along with the dying cells. However, below lies the dermis layer, renewing itself quite slowly. Besides, the space between its cells is filled with a network of collagen fibers — durable and chemically almost inert. Once in the dermis, the pigment grains remain there forever.

Why is the explosion of a grenade in water hazier than on land? In the air, a person is struck by flying grenade fragments. Under water, they quickly decelerate and water pressure serves as the main striking factor. The water set in motion by the explosion presses on the human body. Upon reaching the organs containing air, the pressure sharply squeezes and unclenches them, tearing the tissues. Death threatens the person at a distance of 6-7 meters from the explosion, and the obstacles are almost beyond saving.

Why does the cat invariably land on its feet? The ability to roll over in a fall is innate in cats and manifests itself as early as 3-4 weeks of age. When a cat falls, it instantly begins to level its body with the ground. In this, their highly flexible spine, the absence of collarbones, and well-developed vestibular apparatus contributes to it. It presses its paws and tail to its torso, speeding up the rotation. As soon as the cat gets its paws in a downward position, it immediately moves them aside and the rotation stops.

Why does one’s leg tingle when sit down? The leg "sits up" when the peripheral vessels in it are constricted. The nerve receptors in the limbs are sensitive to the lack of oxygen and respond by shutting down (stopping working). This can be felt as numbness. When the blood supply is restored, the receptors initially generate signals on their own, without external influence. These signals are felt as tingling or goose bumps.

Why cannot you wake up to a bad smell? Recent research from Brown University has revealed the function of smell sensation is altered by the brain during sleep. Although certain substances can affect body activity, we can't wake up from the smell itself. For those who thought of ammonia. It is one of those substances affecting the brain — it stimulates the respiratory and vasomotor centers of the brain and causes increased breathing and increased blood pressure, resulting in waking up.

Why is the whistling sound stronger when it's raining? The reason is that when it rains, the air is damp, i.e. its density is greater than in dry weather. That's why sounds are better transmitted. In rainy weather, for instance, you can hear a train driving on the railroad, especially at night, although at other times you cannot hear it. The molecular weight of water (H20) is smaller than that of the main components of the atmosphere: oxygen (O2) and nitrogen (N2). The lighter the molecule, the higher the speed of sound.

Why do the batteries in a flashlight run out on their own? There are wires running from the battery terminals to the flashlight switch. Even if the circuit is open, the distance between the switch pins is about a millimeter. A weak current can flow through this gap and discharge the batteries. To avoid this, insulate the battery from one of the contacts with a couple of layers of polyethylene or take them out of the flashlight when not in use.

Why does snow shine in the sun? Cause of the crystalline facets. Snowflakes are ice crystals with numerous flat facets that act as microscopic mirrors. Those that reflect sunlight directly into the eye provide a bright dot. As soon as one moves a little bit, the rays of other snowflakes fall into the eye. Therefore, when moving, the shiny spots replace each other. Freshly fallen snow is shinier than lain down, as the flat edges of snowflakes scratch, break, and melt with time.

Why do some animals have vertical pupils while others have horizontal ones? A vertical pupil allows predators to see vertically oriented objects, such as their prey, sharper. Herbivores, on the other hand, only need to view a wide horizon to spot a predator in time, so their pupils are frequently adapted to see horizontal lines more sharply.

Why are raw potatoes unpalatable? Due to the starch in their cells. Though it cannot be seen, you can easily obtain it if you grate the potatoes, pour water on them, and then strain and let them stand. A white sediment is sure to precipitate in the water. That is the very starch which makes raw potatoes bland.

Why do people pay for movie minutes in Germany? Cinema tickets in Germany are expensive, they can cost around €10. That's why it's a good deal for film lovers to buy a monthly pass for €23. Yet you have to pay for extra minutes of film: a subscription includes films of 120 minutes, and time over this limit is paid separately. There is even a special term for this phenomenon: Überlängenzuschlag.

Why cannot gasoline be put out with water? Why are ignited objects put out with water? The point is that combustion is the process of combining a substance with oxygen, so the main purpose of extinguishing fires is to limit the flow of air oxygen to the burning material. Extinguishing with water is the cutting off of oxygen to the burning object, since water, by wetting it, envelopes it (besides, water lowers its temperature). Gasoline isn’t mixed with water, and at the same time, is lighter than water, so it just floats up, while keep burning. In addition, it will begin to spread with the water, increasing the fire area.

Why do sharks not sleep? It used to be thought that sharks don't sleep at all as they need to be in constant motion to pass water through their gills to breathe. Therefore, it seems that a shark cannot sleep since it needs to swim all the time. Still some evidence from physiologists suggests that these sharks may be able to swim and sleep simultaneously. The nerve center responsible for contracting the muscles that move the body is located in the spinal cord, so theoretically they can turn off the brain and doze off on the go.

Why did the 7-up drink originally contain lithium citrate and was a cure for depression and hangover? 7-up was invented by Charles Leiper Grigg in 1920. He came up with the idea of adding lithium citrate to the drink, one of the drugs now prescribed for manic-depressive psychosis. Lithium citrate also helped relieve hangover syndrome. 7-up immediately became popular during the Great Depression and was called lithium-lemon soda at the time. The name was soon changed, but lithium was part of the drink until the 1950s, with 7-up officially considered a patented medicine. There are various versions of the drink's name origin. Some claim the initial recipe contained 7 components, while others recall the atomic mass of lithium, which is seven.

Why do the smells of food spread throughout the house? Due to the heated air. All odors sooner or later spread throughout the volume available to them. With cooking smells, though, this effect is amplified. The point is that the stove heats the air above it as it cooks. As it rises, it forms currents with which odorous substances from cooking and roasting foods are dispersed throughout the room.

Why is one crab's claw larger than the other? These claws have distinct functions. The larger claw, with its powerful teeth, is designed for crushing shells of mollusks and sea urchin carapaces, the prey of the crabs. The second claw has a cutting edge for dissecting soft tissues or bristles serving as a filtration device. In male semi-skinned beckoning crabs, one huge claw has turned into a "tournament weapon": it is used for mating demonstrations and in fights between males.

Why do trees not die in winter? Due to the peculiarities of the cell sap. The cell sap of trees accumulates sugars that lower the freezing point of the sap, preventing it from turning into ice. Besides, the plant's cellulose itself is a nice insulator. Though, severe frosts can lead to the death of the tree. And plants turn most vulnerable after an abundant harvest, since most of the minerals and sugars undergo the formation and growth of fruits, whereas in the trunk cells the latter are present in minimal quantities.

Why does a fly persist in hitting the glass when a section of the window is open nearby? The insect cannot see it. Even if a fly notices an open window, it will have no reason to fly there, as it cannot determine in advance whether there is glass or not. If you bring it close to an open window, it will fly into it at once.

Why doesn't it tickle when you tickle yourself? The brain decreases the sensitivity of the skin. Tickling is caused by irritation of the tactile receptors on the skin. Their sensitivity is controlled by the spinal cord and brain. If the irritation is caused by touching another part of your own body (which the receptors of the touched part tell the brain), the brain dulls the sensitivity of the receptors, preventing the tickle from occurring. Apparently, this mechanism serves to avoid "false alarms" in performing the main function of tickling — alerting us to the presence of foreign creatures on the skin, which may turn out to be parasites.

Why do the names of some currencies derive from measures of weight? The designations of many currencies are closely related to various measures of weight. A typical example is the British pound sterling: sterling was the name given to silver coins, and 240 such coins weighed one pound. Similar is the origin of the foreign currency in several countries called the lira, which is the Italian equivalent of the weight unit pound. In medieval Western Europe, a mark was used to measure the weight of silver, which was slightly lighter than the pound — from it came the Deutschmark.

Why does one's nose turn red and fingers bluish when cold? Vessels in our fingers narrow whereas those in our nose dilate In the cold, the lumen of the blood vessels in the fingers narrows, so the surface tissues turn pale to translucent, and blood stagnates in the deeper layers. By losing oxygen, the blood darkens and, shining through the skin, gives the fingers a bluish tint. The vessels of the nostril walls, on the contrary, expand in the cold: the upper airways, including the nasal cavity, warm the air supplied to the lungs. The colder it is outside, the stronger the heating must be. The increased blood supply to these tissues of the nose leads to its redness.

Why is Facebook designed in blue? In the mid-twenties, Facebook founder Mark Zuckerberg took a color-blindness test and realized that he was color blind. He had trouble distinguishing between shades of red and green. This is one of the reasons why Facebook, and now Meta, are designed in blue – all variations of blue are available to Zuckerberg. In this way, one man's peculiarity influenced the color scheme of the world's most visited site, and may have set a whole trend in social media design. Later VKontakte, Twitter, LinkedIn and Telegram used shades of blue and navy blue in their design.

Why doesn't the bottom button of a jacket get buttoned? This etiquette has been observed since the beginning of the XX century. Historians assume that the rule of wearing a jacket appeared thanks to the English King Edward VII (1841-1910), who was obese. He used to leave the bottom button undone so that a tight vest would fit better. As a sign of respect for his king, the British court, and after him all the inhabitants of England and the British colonies, no longer buttoned the bottom vest. This theory is not taken seriously by everyone, and some trendsetters have challenged it with other versions. Fashion designer Hardy Amies explained the single-breasted suit was first introduced in 1906 and was later called the "leisure suit". It became a casual garment, had a wide cut, and the three buttons gave the suit a proper fit. Over time, the jacket replaced traditional riding coats. And as the third button was below the waist, it was unbuttoned while sitting on a horse for comfort.

Why do all snowflakes appear different? The temperature of the cloud determines the shape of the ice crystal. Also, the amount of moisture in the cloud defines the size of the ice crystal. The more moisture, the larger the crystal. When several ice crystals stick together, they form a snowflake. As snowflakes fall into the air, twisting and swirling, each one goes its own way to the ground. Each single snowflake falls and floats through clouds with distinct temperatures and moisture levels. Thus forming each snowflake in a unique way. Two snowflakes from the same cloud will be of different sizes and shapes due to their separate travel conditions to Earth. Scientists say that the probability that two snowflakes would be exactly the same is about 1 in 1 million trillion. Meteorologists believe there are 1 trillion (with 36 zeros!) unique snowflakes.

Why is it better to breathe through the nose in the cold? The nasal cavity is capable of raising or lowering the temperature of inhaled air. As an example, if you run cold water through a hot pipe, after a while the water will warm up. It is the same with air. This nasal breathing makes the air temperature in the nasopharynx only 1-2 ° C deviates from the body temperature (36.6 ° C). Even when it is -25° C outside, the air in a person's nasal cavity heats up to +35°-36.6° C in a matter of seconds.

Why do sloths tend to hang upside down? That's how they relax. In strict terms, the sloth is not dangling with its head up, but with its back down. It may not grasp a branch, but passively hang on to it on powerful curved claws, like hooks. Sloths spend their entire lives in trees. Resting and sleeping in these conditions requires either a nesting device or anatomical adaptations to keep them from unclenching their paw and snapping off in their sleep. Suspended from a branch, the sloth remains in a completely relaxed state without the risk of falling. Besides, in this position it is less vulnerable to attacks of its main enemy — the monkey-eating eagle.

Why do store prices end at .99? Price ending at .99 is based on the theory that we are used to reading from left to right, with the first number sticking more into our brain than the next. That's why a person is more likely to buy a product that costs 4.99 rather than 5, since subconsciously we feel that 4 is less than 5, even though there's only a penny difference

Why might the electronic clock be lagging? It is due to temperature fluctuations. The "heart" of an electronic clock is a frequency oscillator, where the crystal quartz plate fluctuates. It is set so that the clock runs exactly at room temperature (about 25 °C). As the temperature deviates from this point, the oscillation frequency decreases and the watch lags (up to a few minutes per year). The more expensive models use a thermocompensated quartz, on which the error does not exceed a few seconds per year. Meanwhile, in smartphones and cars, clocks are corrected by precise time signals transmitted over the Internet, cellular networks, and radio.

Why does a giraffe need horns? Defending against predators with these horns is impossible: they are directed backwards, their ends are rounded and covered with skin and wool. Males use the horns for aggressive demonstrations and in ritual duels, but females never do that, although their horns are no less developed. The presence of horns in both sexes prevents them from being considered an ornament to attract sexual partners. So the mystery remains a mystery.

Why are small dogs more aggro than large ones? In part, the aggressive behavior can be explained by the animal's fear of a stranger or another dog. The small size of these animals makes them feel vulnerable. The study also showed that male dogs are more aggressive than females, and older dogs are far more offensive than younger ones. The authors also highlighted another reason and found out why small dogs are nasty: due to the small size of "pocket" breeds, owners think their pets are harmless, so they don't even try to correct aggressive behavior. This can also be a contributing factor to aggressive behavior.

Why cannot a koala be a pet? Of late, the thought of a koala pet has been visiting animal lovers more and more regularly. After all, looking at this charming fluffy animal, resembling a plush toy, one just has the urge to pet and caress it out of control. Though, keeping a koala in captivity is not easy. Mainly due to its diet. After all, the koala eats only eucalyptus leaves of certain species. And nothing else can replace this "delicacy". Besides, koalas prefer to eat at night and do not drink water, except when they are sick.

Why does music give you goosebumps at times? Perhaps all of us have seen how a cat's fur rises up in a moment of danger: it seems both bigger and scarier for a possible enemy. Such a reaction during strong emotions is triggered by the autonomic nervous system, responsible for the functions beyond the control of our will. Listening to music can also cause quite acute feelings of an aesthetic nature, exciting the nervous system. Though it is true that people lack fur, but small hairs on the skin tend to rise. To this end, the muscles of the hair follicles contract, which gives rise to goosebumps.

Why does a turtle's shell consist of hexagons? Cells of such a shape make it the easiest to build up. As turtles grow, their shells have to grow along with them, evenly over the whole area. That's why the turtle's shell is formed of individual plates, tightly fitted to each other like planks of parquetry, but retaining the ability to grow at the edges. If the plates could grow evenly in all directions, they would be shaped like circles. Yet the circles could not stick tightly next to each other, there would inevitably be gaps between them.

Why shouldn't one smile when encountering a fox? Healthy foxes habitually avoid populated areas and visit them only after feeling strong hunger. Although foxes infected with rabies are not afraid of humans and can attack them. Judging by the animal's appearance, it is hard to tell if it is sick or healthy. When meeting a fox, you should not approach it and make contact. Even if you really want to pet or feed it. Nor should you look the predator in the eyes and smile at him: a fox's smile can be mistaken for a grin and, in order to protect itself, it can attack. When facing a fox, it's best to look away, observing the animal with your peripheral vision, and start walking back slowly, without turning your back to the predator.

Why do ice cubes crack in water? Frozen water retains its crystalline structure only at temperatures below 0°C. For this reason, ice cubes tend to crack when you put them in water or any other drink. The explanation for this phenomenon is quite simple — when the ice is in the liquid, its temperature around the cubes begins to decrease, and the temperature of the ice itself — to increase. Due to this, the bonds that keep the water in the solid phase are broken, and you hear a crash, and cracks appear inside and on the surface of the cube.

Why does the boomerang fly back? The shape of the boomerang and the way it is thrown are such that in flight it is subject to an aerodynamic force directed perpendicular to its trajectory. As a result, the boomerang does not fly straight ahead, but all the time it goes sideways and returns approximately on a circular trajectory. Unless, indeed, it hits its target on the way. Still, there are boomerangs flying straight ahead and using aerodynamics to increase their range.

Why were parrots the closest companions of pirates? These bright exotic birds reminded the robbers of distant countries and islands. Yet the most remarkable thing is that parrots are able to memorize words and copy human speech. Birds quickly become tame, easily follow the call of the owner, and some are true interlocutors. Over time, this feature has entered so much into folklore that we no longer imagine the old pirate with nothing but a wooden leg and a parrot on his shoulder.

Why do moose and deer shed their antlers, but cows and antelopes do not? Bulls, goats, and antelopes have short, sharp horns. They are used not only as tournament weapons, but also for defense against enemies, so both sexes are commonly horned. Only males of moose and deer have antlers (with the exception of reindeer, but even those have much smaller antlers of females). During the mating season, antlers make it possible to distinguish males and females from afar. This triggers the corresponding behavior. An animal with small antlers is less likely to attract females. After the mating season, males get rid of these structures that weigh down the head and make it difficult to move through the forest.

Why are cats unable to see red, yet capable of distinguishing 25 shades of gray? Cats, likewise humans, have two types of photosensitive cells (rods and cones). Yet whereas in humans there are four rods per cone in the area of clearest vision, cats have 25. Cats see colors much worse than we do, red, in contrast to blue, as an example, is completely inaccessible to them. On the other hand, when it comes to "seeing" shades of gray, cats are real record-breakers: they can distinguish 25 types of mouse colors. Also due to this cats have surprisingly good night vision.

Why do pigs enjoy wallowing in mud so much? Pigs lack sweat glands and cannot sweat even on the hottest days. That's why they like to roll around in the cool mud, chilling themselves in this peculiar way. In addition, after such a mud bath, sensitive skin is covered with a crust that protects against sunlight and insect bites.

Why is a clapper used in filming? A clapper, or numerator, is a tool applied in filmmaking to synchronize the image and sound recorded on an independent motion picture and recording device after filming. Furthermore, the clapper is used to organize the footage and recorded soundtracks by marking the numbers of scenes and takes

Why is there an ice cream cemetery in Vermont? The state of Vermont has an ice cream cemetery. It was set up by Ben & Jerry's, one of the most famous ice cream brands in the United States. Real tombstones are erected there for lost or simply failed samples of the product. Among them, for instance, is White Russian, reminiscent of the eponymous cocktail of vodka and coffee liquor.

Why do ants follow each other in a chain? So as not to lose their trail. The scout ants travel along a complicated path while searching. When they find food or something else relevant, they return to the anthill by the shortest route, marking it with scent secretions. The ants mobilized by the scout move along this path, also leaving scent trails. Each ant tries to stick to the chain of trails it has already laid, and as a result, the insects follow one another.

Why were the stairs in the towers of medieval castles twisted clockwise? The spiral staircases in the towers of medieval castles were built in such a way that the ascent by them was clockwise. The purpose of the design was to give the defenders of the tower a fighting advantage in case of a castle siege as the right-handed attacker could only strike the strongest blow from the right to the left that was inaccessible to his attackers. However, if most men in the family were left-handed, they built castles with a backward twist — such as the Wallenstein Counts' fortress in Germany or Ferniehirst Castle in Scotland.

How many horsepower is in a horse? From 0.3 to 3. The concept of "horsepower" was introduced by the Scotsman James Watt to describe the power of his steam engines. Observing horses lifting barrels of rock from a mine, he estimated their average force at 33,000 pounds per minute. In other words, horsepower corresponds to moving 75 pounds one meter up in one second. But at that speed, a horse can only pull 15% of its weight for a long time, so an individual weighing 500 kilograms develops 1 hp. In modern units, that's 735 W. Horses vary in weight, though. A pony weighing 170 kg is unlikely to produce more than a third of the horsepower, while a one and a half ton heavyweight can work for three horses. And in a jerk the average horse is capable of producing 15 hp.

Why are cars called Toyota, although the company founder's last name is spelled Toyoda? Sakichi Toyoda, who invented the automatic loom and founded the Toyoda Automatic Loom Works, is considered the "father" of the Japanese industrial revolution. In 1933, under the leadership of his son Kiichiro Toyoda, car production was initiated. At first they were sold under the Toyoda brand, but then it was decided to change the penultimate sound. The word Toyota in Japanese alphabet requires eight brush strokes instead of ten for the word Toyoda, and the number 8 is traditionally considered lucky in East Asian countries. Another argument in favor of the renaming was to distance itself from associations with agriculture, since the literal meaning of Toyoda is "harvesting rice fields".

Why is gum banned in Singapore? To keep the city clean, the city has banned chewing gum since 1992. The city government had to spend huge resources to clean public spaces of gum that people threw away or, worse, glued to the seats in transport. In Singapore, gum can only be bought in a pharmacy with a doctor's prescription for medicinal purposes. Penalty of S$5500 and 1 year imprisonment is for importation for sale. Before you visit Singapore, be sure to check your pockets and get rid of any chewing gum you may have. If you do get caught with gum, you will have to pay $1000.

Why does Mona Lisa have shaven forehead hair and plucked eyebrows? In Western Europe in the 15th century the ideal of a woman was as follows: S-shaped silhouette, curved back, round pale face with a high clear forehead. To match the image, women shaved their forehead hair and plucked their eyebrows, just like Mona Lisa in Leonardo's famous painting.

Why cannot people breathe and swallow at the same time? The human vocal apparatus allows humans to speak. At the same time, its intricate structure does not enable humans, unlike animals, to breathe and swallow simultaneously. Although newborn babies can do this, they lose this ability at approximately 9 months of age. Once we reach this age, our vocal apparatus sinks lower, so that we are capable of producing a wide range of distinct sounds that form speech. After this point, though, we can no longer breathe and swallow at the same time.

Why do people have different sensitivities to extraneous noises during sleep? Our brain has the ability to actively filter incoming auditory signals in order to weed out the unimportant and focus on the important sounds. The thalamus structure of the brain plays a major role in this process, where the primary processing of all sensory information takes place, and during sleep its work not only does not stop, but also is modified. Scientists have detected sequences of short impulses on the electroencephalogram of the brains of sleeping people, which are believed to serve as a kind of barrier to noise, allowing us not to react to it. Moreover, the number of these impulses varies from person to person, and those with fewer impulses are more likely to wake up to noise.

Why is Costa Rica so named? In 1502 Columbus's expedition landed on an unknown shore and noticed local Indians wearing gold jewelry. Thinking that there are deposits of gold, the Spaniards named their discovery Costa Rica, which means "rich coast”. Later it turned out that Costa Rica is pretty poor in minerals.

Why is there no candle smoke when burning, but a lot of it if you blow candle out? When the candle burns, the smoke burns with it. The smoke is the evaporating wax. When you extinguish the candle, the wick is still hot enough to continue to evaporate the wax. Still not hot enough to ignite it again. But if you cool the wick, for example by wetting it, it will no longer be hot enough to evaporate the wax. In that case there will be no smoke either.

Why do mom and dad sound similar in most of the world's languages? In most of the world's languages, the words "mom" and "dad" have a similar sound. This is not due to the common origin of all languages, but because these words are the first word-like sounds spoken by babbling children.

Which tastes better as Coca-Cola or Pepsi? In fact, there is little difference between Coca-Cola and Pepsi, but the tastes are still different. When volunteers did not know which beverage they were drinking, the preference averaged 50%. However, when the participants were told the name of the drink, the preference also changed. As a result, people claimed that Coca-Cola tasted better. Why? When participants didn't know the names of the drinks, fMRI recorded the activity of the pleasure center, which is located in the front of the brain and is known as the ventromedial prefrontal cortex. This area of the brain is particularly sensitive to foods that most people like (like sugary carbonated drinks). However, when volunteers were told the name of the drink, the fMRI began to record activity in the part of the brain responsible for emotion and perception. Coca-Cola elicited more emotional reactions in people than Pepsi.

Why aren't cockroaches afraid of radiation? Insects are indeed less sensitive to the effects of radiation than vertebrates. This is primarily due to the fact that the former have a much lower percentage of dividing cells, which are mostly vulnerable to radiation, and possibly a weaker metabolic rate. However, the resistance of cockroaches to radiation is not record-breaking: for example, mealworms tolerate much higher doses. There are no animals that are completely insensitive to radiation.

Why aren't wolves trained? Wolves are pack animals; they only feel good together. A wolf pack is a highly socialized group, in which each animal has its own social role. A solitary animal does not survive in the wild, it is driven out of everything, so the wolf's life depends on the pack. So, it's not one animal that needs to be trained, but the whole pack, and that's impossible.

Why do cats and dogs lack a bellybutton? They have it. Cats and dogs, as well as all mammals except marsupials and egg-laying mammals, have bellybuttons, as you can easily see by scratching their bellies. However, bellybuttons of animals look different than human ones — they resemble a small scar without a wool cover.

Why does the Google logo change around the holidays? ⠀ In 1998, Google founders Larry Page and Sergey Brin wanted to let users know that they had gone to the Burning Man festival, which ends with the burning of a huge wooden figure. They put a drawing of a wooden man behind the second letter O of the logo, so that everyone would know that they were now out of the office. That's how the idea of decorating the logo to celebrate important dates and holidays came about. Users were pleasantly surprised by the unexpected change in a simple logo. So in the same year on Thanksgiving a turkey appeared on it, and in October 1999 on Halloween instead of two O's pumpkins were flaunted in the logo. These doodles were followed by others.

Why are some eucalyptus and pine trees found to be shy? Some tree species have what is called crown shyness. It manifests itself in the fact that their crowns in a dense forest do not touch, forming zigzag gaps. There is no single explanation for the cause of this phenomenon, but there are several versions, among them the prevention of the spread of insect pests or the avoidance of collision damage from wind exposure. Trees with revealed crown shyness include, for example, Dryobalanops aromaticus, twisted pine, and several species of eucalyptus.

Why do zoo workers manually swap baby pandas for mothers to feed? About half the time, big pandas give birth to twins, but the mother almost always gives up one baby because it doesn't think it has enough milk and energy to feed two. In some zoos, to preserve the offspring, zookeepers resort to a trick: they change cubs several times a day, and while one is nursed by its mother, the other is placed in an incubator and fed with a milk mixture.

Why won't the Chinese fly to the ISS? Chinese astronauts will not be able to visit the ISS in the near future, because back in 2011 the U.S. Congress voted to ban any space cooperation with China. But this fact has not upset the Chinese: their astronauts fly to their own space stations, which China builds and launches on its own.

Why are cats afraid of water? They don't want to get cold. Cats have a layer of air between their skin and fur that plays an important role in the body's thermoregulation. Wet fur stops protecting the cat from freezing, and its whiskered friend can't dry off quickly.

Why does paper turn yellow? Due to the oxidation of the cellulose in it. The color of many chemical compounds is given by the chromophores in their molecules, from the Greek words "chroma" (color) and "phero" (carrier). These are usually groups of two or three atoms that absorb light waves of a certain color. In 2012, Italian scientists calculated that chromophores, consisting of a carbon atom linked by a double bond to oxygen and one bond to hydrogen, are responsible for the yellowing of paper. Such groups are formed during the slow oxidation of cellulose by air oxygen.

Why is it important to apply flea remedies only to the back of your pet's head? Flea drops contain an insecticide (usually fipronil) and a mixture of organic solvents. When applied to the back of the head, these substances spread throughout the pet's body in a couple of days. In order to kill parasites on any area of the skin, the initial concentration of insecticide must be quite high — up to 10%. Therefore, the drug is applied in a place inaccessible for licking. Fipronil is non-toxic for mammals, but in high concentrations it may cause abundant salivation and probably unpleasant taste.

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Why is butter yellow when milk is white? Butter consists of more fat. Dairy fat is given its color by carotenoids, the red-yellow pigments, particularly vitamin A. Fat is present in both milk and butter. Still in milk it is in the form of an emulsion, a suspension of droplets the size of 3-4 microns. Each droplet is surrounded by the thinnest protein-lecithin shell. Liquids of this structure look whitish because of light scattering on the surface of the droplets, regardless of the color of their contents. In butter, the proportion of fat is higher, causing many of the emulsion droplets to merge with each other. The light scattered on them is worse, and the natural color of the fat appears stronger. Ghee, which is almost pure milk fat, looks even more yellow.

Why does it get darker in winter than in summer? In a year, the Earth makes a complete revolution around the Sun. It moves at a certain angle. In the cold season, our hemisphere deviates significantly from the Sun, the size of the angle increases, and the sun's rays pass tangentially across the surface of the Earth, delighting at the same time for a short time. Therefore, it gets darker earlier in winter. In mid-December, the tilt of the Earth's axis to the sun reaches its greatest angle – the day lasts only 8 hours. The turning point comes in mid-June, when the days start to get shorter. The principle of this natural phenomenon can be explained visually with the help of a flashlight and a globe. Put the Earth in miniature on the table and direct the beam of light from the flashlight perpendicularly, while spinning the globe around its axis. If the light is directed from the other side, parts of the globe will be illuminated differently.

How did the name Snickers come about? The Snickers bar was first made in 1923 in the United States by confectioner Franklin Mars, but its mass production did not begin until 1930. The Snickers bar was named after the name of the family's favorite horse. In November 1929, a chocolate factory was built in Chicago, where the first Snickers candy bars were made. By the turn of the twenty-first century, the Chicago chocolate factory was producing 560 sweets a minute on a separate production line.

Why does the runny nose appear? When you get sick, the immune system becomes active, and small proteins cytokines activate special T-cells and B-cells to find and destroy pathogens. These same proteins command the nose to generate more mucus to clear the cellular epithelium of other potentially harmful bacteria and viruses. The nasal cavity fills with excess fluid, which we call snot. They keep other dangerous viruses and bacteria out while the body is weakened.

Why does tea leave stain on the cup? Tea leaves contain phenolic compounds, tannins, which give a strong drink an astringent taste, and alkaloids, primarily thein. When the tea is brewed, these come out in solution and react with each other. As it cools, the solubility of this compound drops and it is partially released on the surface of the liquid as a film. When the cup is tilted and sipped from it, this film ends up on the walls and dries out. Stain is not harmful to health, but its regular occurrence is a reason to think about whether the tea you drink is too strong.

Why can't we put burning food in the refrigerator? Refrigerator manufacturers do not recommend putting hot food into the refrigerator, and say to cool it down to room temperature beforehand. Accordingly, if you put hot food in the refrigerator, it will not turn off for longer — hence the increased load on the compressor and electricity consumption. The service life of the refrigerator decreases.

Malevich's "Black Square": why is it art? Malevich lived in an era of change, the world was crumbling before his eyes and out of the rubble something new was being created, still incomprehensible, but well tangible. Traditional painting was no longer relevant and the visual arts had to make a revolution. Artists were looking for new forms of expression of their ideas. Thus the avant-garde – a trend in art, and in the fine arts in particular – appeared. Kazimir Malevich decided to take this quest to its limits. By cutting off the secondary details, increasing the emotional impact on the viewer and clearing the idea of the work of double meaning, the icon of avant-garde artists — “The Black Square" was born. Only two colors, black and white, give the strongest visual contrast. The rectangular, static form cuts off any associations with the visible world. The lack of details and explanations in the form of text emphasize the conciseness of the idea. This is the absolute. Intellect in its purest form.

Why cannot we see the dark when blinking? ⠀ A person blinks on average every 15 to 20 seconds with a duration of 50 to 75 ms, with no noticeable change in the observed pattern. ⠀ We do not notice the blinking process and continue to observe the uninterrupted pattern, even though we must sink into darkness for this time, because we do not perceive the flicker of a light source lasting only 0.03 seconds.

Why are puzzles and riddles useful? We enjoy learning anything new, even if we don't realize that solving crossword clues, Sudoku or puzzles is part of this process. By brainstorming a problem with no practical application, one satisfies curiosity, seeks various ways of solving it, and feels the joy of victory. Smaller discoveries amuse one's ego and awaken interest in mental work. For active adults, solving puzzles is an opportunity to switch gears. Gymnastics for the mind is no less useful than physical exercise, it relieves stress and helps to maintain intellectual fitness.

Why is fiber not digested? Insoluble fiber is not digested by our body and is not fermented in the large intestine. As it passes through the gastrointestinal tract, insoluble fiber absorbs fluid and digests byproducts. Insoluble fiber is not digested, it increases stool volume — if you eat a lot of fiber, it will be regular and comfortable. It is easier for the intestines to work under these conditions.

Why does the carving of a 12th-century Spanish cathedral show an astronaut in a spacesuit? On the carvings of the New Cathedral of Salamanca, built in the 16th-18th centuries, you can find the figure of an astronaut in a spacesuit. No mysticism here: according to a local tradition, every time buildings are restored, elements reflecting modernity are added. One of the craftsmen chose the astronaut during the next restoration in 1992. Vandals have since damaged the hand and face of the figure, making it look as if it has survived the centuries.

Why is it believed that hair grows faster and gets darker after the first shave? The notion that hair grows faster and gets darker after the first shave is mistaken. It's just that initially the hair has thin, blond tips. After they are shaved, the hair grows upwards with blunt, dark ends, which creates the illusion.

Why does Jomolungma have a second name, Everest? Since the first one was not known to surveyors. In the 19th century, the British were surveying in the Himalayas. They could not get on the territory of Nepal which was closed to foreigners and they measured from India more than 200 kilometers away from the Nepalese peaks. At that time the highest mountain was Kanchenjunga on the Nepalese-Indian border. In 1852 the Indian mathematician Radhanath Sikdar, on the basis of measurements taken by the British, calculated that the mountain, conventionally called Peak XV, was higher than Kanchenjunga. It had to be given a name by which it would be recognized in the world. Not knowing the mountain's Tibetan name (Jomolungma), Andrew Waugh, head of the British India Survey, named the peak after his predecessor in that position, George Everest.

Why doesn't food burn on oil? Oil prevents overheating. Food does not conduct heat well. When frying in a "bare" pan, the bottom layer of the food gets so hot that it can char, while the top of the piece stays raw. The oil transfers the heat from the lower layers to the upper ones. The main thing is that it, like any liquid, cannot get warmer than its boiling point since the incoming new heat is carried away with the vapor. The boiling temperature of oil is sufficient to form a crispy crust on food. Cooking and braising do not produce crusts: in these cases, water, which has a relatively low boiling point, plays the role of a stabilizer.

Why is it wrong to burn trash in volcanoes? ⠀ Cause dumping trash into the lava lakes of volcanoes can trigger an eruption. Lava lakes are unstable, so if you puncture their surfaces with something cold, like trash, you trigger a chain reaction of explosions with compressed and acidic vapor. ⠀ Also, all the moisture accumulated in the waste instantly evaporates, the steam expands, escapes outward, tears up the debris and creates bursts of molten rock.

Why do trees need bark? Tree bark can probably be compared to human and animal skin, only it is infinitely rougher and stronger. The bark mainly serves to protect the inner, more delicate part of the tree. It can withstand both the searing heat of the summer sun and the blistering cold. Moreover, the strength of the bark is astounding: in some trees, it can even resist fire.

Why do lint appear? Lint is the loose fibers or balls of fabric that form on the surface of the material. The reason for their appearance is friction on the surface of the fabric or abrasion from rougher surfaces. Coils on clothing are considered unaesthetic. The most frequent reason for the formation of lint on clothing is due to improper care of the clothing. Daily wear, washing and drying at inappropriate temperatures have an adverse effect on the fabric, resulting in the formation of lint. Items made of polyamide (nylon), capron, lavsan (polyester and polyamide fibers) are particularly prone to the formation of lint. Among synthetic fabrics, acrylic is less prone to lint.

Why does the female praying mantis eat the male after mating? In fact, the female mantis eats the male because of her strong need for protein during the early stage of egg development. However, after eating the male, the female praying mantis also dies, immediately after laying eggs in the nest she made of foamy mucus. Such is the tragic fate, the reproduction of these insects. To produce offspring, the pair is doomed to die.

Why does a camel spit? Camel spitting is an element of threatening behavior in a conflict between individuals, mostly males. In this way, the male intends to force its rival to admit defeat without seriously injuring it and without getting hurt itself. After domestication, camels began to use this form of behavior also in conflicts with humans, especially strangers whose actions seem dangerous or irritating to them.

Why are there indentations on the golf ball? These "indentations" on the ball are needed to increase the range of the ball. So air flowing around an uneven ball reduces the vacuum trace created by speed. Thus the boundary layer of air in a smooth ball doesn't have time to go behind its back side, so it creates a zone of reduced pressure, which means less velocity.

Why is the prison uniform striped? ⠀ The striped uniform made it possible to quickly locate a fugitive. It did not blend in with the surroundings and helped find the prisoner. In addition, such a color of clothing immediately singled out a fugitive from the crowd of people. The uniforms of modern colors — red, orange and yellow — also do an excellent job of these functions. ⠀ Another purpose of striped uniforms is uniformity. In prisons absolutely all prisoners wore robes with black and white stripes. Such uniformity and identical clothing had a psychological effect, reducing the inmate's initiative.

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Why shouldn't plastic containers be used at gas stations? Plastic tends to accumulate static electricity. Think of an electrified comb that "shoots" a spark. The same spark can form when a flammable liquid rubs against the walls of a plastic container, causing it to ignite.

Why do we say "hello" when answering the phone? ⠀ In Japan, phone callers are greeted with the phrase "mighty-mighty," and in China, when picking up the phone, people say "wei”. Russians, like most of the world, say "hello”. But why exactly "hello"? ⠀ The first version insists that the word has Norman roots. When William the Conqueror invaded England, he heard local shepherds shouting "Hallo!" as they gathered their sheep. From this word the verb halloer, "to shout," was later formed. According to another theory, the word "hallo" was formed from hallow, which English sailors used to say when meeting ships. A third option suggests the Hungarian origin of the telephone greeting. In that language there is the word hallom, which translates as "I hear you." The word became popular thanks to Tivadar Puskás, the man who founded the first telephone news service. It was the word he used at the beginning of the broadcast.

Why is the gas tank on the left side of some cars and the right side of others? In European automakers, the gas tank neck is most often located on the right side of left-hand drive cars. This is explained by the convenience of refueling — the driver does not have to fear hitting the door on the gas tank, and the fuel vapors need more time to penetrate into the cabin through the open driver's door. Some Asian brands ship left-handed cars to foreign markets with left-handed throats. This is most likely due to the fact that an additional change in design would increase the cost of manufacturing the car, and the position of the neck, by and large, is not that important. In rare cases, the side of the gas tank hatch location is due to design features, but this is the exception rather than the rule.

Why does orange juice get bitter after brushing my teeth? According to Live Science, the strange bitter taste of orange juice after brushing your teeth is due to the presence of a compound called sodium laureth sulfate in toothpaste. Sodium laureth sulfate provides effective foaming and cleansing in toothpaste as well as in shampoos, cosmetics and detergents. This substance temporarily inhibits the tongue receptors that recognize sweet taste. Another side effect is that sodium laureth sulfate breaks down compounds called phospholipids in saliva, and phospholipids help soften the bitterness effect of what one eats or drinks. Drinking orange juice before brushing your teeth is not a good idea. Sour foods and drinks weaken tooth enamel, especially if consumed just before brushing. Orange juice can also contribute to tooth decay.

Do dolphins like to eat fugu fish? Dolphins occasionally resemble humans more than we can imagine. The creators of the documentary noticed a strange thing: teenage dolphins were carefully chewing on fugu fish and passing them to each other. Fugu is known for containing a lethal dose of a neurotoxin in its body, yet in small doses this substance produces a narcotic effect, and the dolphins seem to be well aware of this.

Why are walks in a coniferous forest so beneficial? Scientists have proven the air in a coniferous forest is virtually sterile (no more than 200-300 harmful bacteria per cubic meter). A walk in the woods relieves stress and nervous tension, tones the body by activating gas exchange in the lungs and, consequently, improves breathing. Such walks are vital for heavy smokers and office workers.

Why does a cat catch mice and bring them to its owners? Researchers believe it can be explained by either of two possible reasons: A sign of affection for the owner. Cats enjoy hunting mice and playing with them, maybe so do you? Parental instinct. Cats are known for their tendency to share food with family members. Either way, it's a form of expressing their care and love.

Why do lions have manes and other felines do not? ⠀ Due to their way of life. Unlike other felines, lions live in prides, a community consisting of a male, several females and cubs of all ages. Members of the pride meet with each other constantly, not only in the mating season. In such a lifestyle, signals regulating aggression are useful, including the ability to determine the sex of a tribe mate from afar. The mane, a distinctive feature of the adult male, serves this purpose.

Why does Asians eat with chopsticks? ⠀ Most likely, it was due to the rapid growth of the country's population: food was in short supply, so the Celestials cut it into small pieces to cook it faster and make it easier to divide among a large group. ⠀ Small sliced food is nothing to cut with a knife, however, handy to take with chopsticks, which in addition are extremely easy to make and cheap, so the innovation quickly spread across the country.

Why is the American teddy bear called Teddy? In late 1902, U.S. President Theodore Roosevelt traveled to Mississippi to settle a border dispute between that state and neighboring Louisiana. On a day free of negotiations, the guest was invited to go hunting. They failed to get a beast, and to please the president, he was shot with a bear cub he had caught beforehand. However, Roosevelt refused to shoot. The Washington Post published a story about the incident. A few days later, Morris Michtom, owner of a Brooklyn stationery store, displayed a rag-tag bear in his window with a sign that read: Teddy's Bear. Wanting to buy the toy was so much that Michtom even founded a company for its production. The teddy bear was named Teddy.

Why is Black Friday — black? Originally the action was held only in America, and from the beginning of the XIX century. The first sale was held in Pennsylvania. The pioneer of the action was a young guy — Frank Woolworth, who without the consent of the owner of the store decided to sell all seasonal items for 5 cents. Such a move brought commercial success to the shop where he worked, prompting him to organize one of the largest retail chains. Pricefall was commonly called in 1966. This day was dubbed "Black" by the U.S. Patrol, cause the discounts provoke a huge stir — the number and duration of traffic jams increase, and fights sometimes break out in the stores.

Where and for whom was an umbrella invented? The birthplace of the umbrella is considered to be China and Egypt. In both named countries umbrella was considered a symbol of power, only the pharaohs or emperors and close associates of royalty could use umbrellas. Umbrellas were 1.5 meters high and weighed about 2 kg. The cult of the umbrella also existed in African countries, where it was a symbol of power along with the crown. Next time someone asks "why do you need an umbrella", say "commoners do not understand".