Can Holding in a Fart Kill You?: Over 150 Curious Questions and Intriguing Answers

CAN THE GREAT WALL OF CHINA BE SEEN FROM SPACE?

It is commonly said that the Great Wall of China is the only human-made structure that can be seen with the naked eye from space or the moon. This assertion has been perpetuated as a question in the board game Trivial Pursuit. It has also been included in schoolbooks across the world, and was stated as true by the Ed Harris character in the 1998 movie The Truman Show. In addition, Richard Halliburton’s Second Book of Marvels makes this claim (despite the fact that the book was published in 1938, before space exploration had begun).

One school of thought is that the claim was made to convey the enormous scale of the wall and the vastness of human achievement in building it. It is now accepted that the statement is false.

From a low orbit of Earth (up to about 200 miles), many human-made objects can be seen with the naked eye. Highways, airports, buildings, and ships, as well as the Great Wall, can be seen. The wall’s width ranges from about 15 to 30 feet, but when dust storms hit it, it becomes more visible at this close range because of the combined size of the wall and the dust turbulence.

But no human-made structures are visible with the naked eye above an altitude of a few thousand miles, and certainly not from the moon. The moon is around 240,000 miles away, and from there, entire continents and oceans are barely visible without mechanical assistance. These facts have been confirmed beyond any doubt by a number of astronauts.

WHY IS THE OCEAN SALTY?

The oceans of the world cover around 70 percent of the Earth’s surface. They are filled with salt, and—despite much mythology on the topic—it is not commonly known why.

There are many constituents of seawater, but the primary chemicals are sodium and chloride. These are the components of salt and account for the salty taste of the ocean.

All water contains some salt, but the salts in seawater are increased by the gradual dissolution of the Earth’s crust and the erosion of rocks and mountains. Rainwater is slightly acidic from the carbon dioxide it absorbs from the air. When rain falls to the ground, its carbonic acid erodes rocks and forms ions (mainly sodium and chloride ions). Rainwater and rivers then transport these minerals from rocks and soil to the sea, increasing the salt content.

The salt content of the ocean is also augmented by evaporation. The sun evaporates freshwater from the surface of the ocean to the atmosphere, leaving the salts behind. This process is known as the hydrologic cycle. Because only freshwater is evaporated and rain brings more salts to the sea, as time passes, the oceans are actually becoming saltier. In fact, it is thought that the oceans contain 50 million billion tons of salt and that if all the salt was removed from the world’s oceans and spread across the land, the layer would be approximately 180 yards (165 meters) thick.

The salinity of different oceans varies according to location. In areas of high water temperature, the evaporation rate is increased, leading to saltier water. Oceans that are remote from land also receive a smaller influx of freshwater, which increases their salinity. In polar areas where the salt is diluted by melting ice and excess rain, salinity tends to be low. The saltiest areas of all the oceans are the Red Sea and the Persian Gulf, where evaporation is at its highest.

WHAT CAUSES HEADACHES?

Medically known as cephalalgia, headaches have a multitude of causes, such as sleep deprivation, dehydration, stress, eyestrain, sinus pain, and muscle tension.

Where there is a disorder or pain somewhere in the body, nociceptors, which are pain-sensitive receptors at the ends of nerve fibers, are activated. The nociceptors send a signal to the brain, which the brain interprets as pain. A headache results. The area of the head where the pain is felt depends on the location of the activated nociceptors.

When the brain is alerted to pain, it also produces a number of chemicals, including serotonin, that act to reduce pain. However, the release of these chemicals can cause a swelling of blood vessels in the brain, making the blood vessels tender. The swollen vessels then irritate the nerve fibers that surround them in the head. These nerve fibers send messages to the trigeminal system, which is an area of the brain dealing with pain in the face and head. This can cause the headache to worsen.

Medication to alleviate the effects of a headache works best if taken early. Once the pathways for the pain signals, transmitted by the nerves, are fully activated, it is more difficult to prevent the signals and thus reduce the headache.

HOW DO GUN SILENCERS WORK?

A silencer, also known as a suppressor, is a device that is attached to the end of a gun barrel to reduce the amount of noise that is generated when the gun is fired.

When the trigger of a loaded gun is pulled, gunpowder is ignited, which creates high-pressure hot gas. This expanding gas forces the bullet down the barrel of the gun, resulting in a loud noise as the bullet exits.

The silencer is usually a cylindrical piece of metal that is screwed on to the end of the barrel, although it can be attached to the gun as a permanent fixture. It is composed of a group of baffles inside an expansion chamber. The baffles are hollow plates that divert the flow of the gas within the expansion chamber, which is larger in diameter than the barrel of the gun. This allows the gas to cool and reduce in energy. As the gas leaves the expansion chamber, its pressure and speed are less. This greatly reduces the sound when the bullet and gas are released. In this way, the silencer has a similar effect as the muffler of a car.

Silencers are most effective when attached to small-caliber weapons, especially when subsonic bullets are used. These are bullets that make less noise, as they travel slower than the speed of sound. Some silencers use small quantities of oil or water to cool the gas and reduce its pressure. These are known as wet suppressors.

The term silencer is actually a misnomer, as a silencer only decreases the noise created—it doesn’t eliminate it. Silencers are often depicted incorrectly in movies and on television shows. In these fictional portrayals, virtually no sound is heard when a gun with a silencer is fired.

The commercial silencer was invented by Hiram Maxim and first sold in 1902 in the United States. The legality of the silencer varies widely in different parts of the world.

WHAT IS THE ORIGIN OF THE SCOTTISH KILT?

One of the most widely recognized traditional garments for men, the kilt is associated with the Scottish Highlands. The word derives from kjilt, a Norse word meaning pleated. The kjilt was a similar item of apparel worn by Viking settlers.

The great kilt dates back to at least 1600 in Scotland, when it was worn by military troops. It was a large garment (around 5 yards long), worn by draping it across the shoulder and over the body. The lower portion was gathered in pleats and secured with a belt. It provided ideal protection from the cold and the elements.

The origin of the smaller and more convenient modern kilt has been the topic of heated debate. Many say that it was invented in 1720 by Thomas Rawlinson, who was English. He owned a charcoal production plant in Scotland and had the great kilt tailored to make it more practical for working men. However, it is now known that the modern kilt was worn before Rawlinson, and one, which resides at the Scottish Tartans Society, has been dated to 1692. By the mid-1700s, the modern kilt had become popular throughout the Highlands and parts of the Lowlands. When parts of the Scottish military were deployed abroad, the different regiments were assigned different tartans as a means of identification (although some say the tartan was used to distinguish different clans of people in Scotland).

In 1746, the English government controlled Scotland. Wary of a Highland uprising, the English government prohibited Highlanders from possessing arms. The Dress Act was also enacted, which outlawed all aspects of Highland attire, including the kilt. This ban lasted for 35 years, during which time many Highland customs were lost. Upper-class Scots set up societies advocating the resurgence of ancient Highland dress. The Celtic Society of Edinburgh encouraged Lowlanders to join them, and the movement gained momentum. In 1822, King George IV visited Scotland and wore a kilt. Queen Victoria then promoted the wearing of kilts, and the style became widespread.

Today, kilts are commonly worn at Scottish formal occasions, although some continue to wear the kilt daily.

WHAT MAKES POPCORN POP?

First developed by Native Americans, popcorn has been popularly sold in movie theaters since 1912. The first commercial popcorn machine was invented in 1885 in Chicago.

Popcorn is an ancient type of maize that is specially cultivated to increase the corn’s ability to pop. In fact, popcorn is the only type of corn that pops, and the name comes from the Middle English word poppe, which means explosive sound.

Popcorn is able to pop because its tiny kernels contain a small amount of water (at least 14 percent is required). Unlike most corn, popcorn’s kernel is encased inside a hard, waterproof outer shell. When heated with oil to around 350°F (175°C), the water evaporates and expands, creating high pressure, which is unable to escape. This pressure builds and eventually forces the outer casing to explode, turning the kernel inside out. The sudden explosion changes the starch inside the kernel into a light foam, and gives cooked popcorn its peculiar appearance.

Popcorn coated with butter is the most popular variety, and the kernels that fail to pop are known as old maids.

WHAT CAUSES A STITCH DURING EXERCISE?

A stitch, formally known as exercise-related transient abdominal pain (or ETAP), is a sharp, stabbing pain that commonly occurs just under the rib cage during exercise. A stitch can also result in a stabbing pain in the shoulder blade, which is thought to be a pain referral site for the abdomen.

It is not entirely clear what causes a stitch. It was traditionally thought that exercise makes internal organs, such as the liver, pull on the ligaments that connect the gut to the diaphragm, resulting in stress, or a stitch. Others believed that a stitch is caused by blood being redirected away from the diaphragm to the limb muscles used during exercise.

It is now commonly thought that a stitch results from the irritation of two layers of the membrane lining that is inside the wall of the abdomen. The two layers are separated by lubricating fluid, which allows them to move against each other without friction. Scientists believe that a stitch is the pain that occurs when the two layers rub against each other and create friction. This is thought to be caused by either a reduction in the fluid that lubricates the two layers or by a distended stomach forcing the layers close together. This friction is generally more likely to occur during exercises that involve an up-and-down action, such as running or jumping.

Eating or drinking inappropriately before exercise can result in a full stomach or dehydration, the latter causing a lack of lubrication. Both can lead to a stitch. The best way of avoiding a stitch is to drink water or sports drinks, which empty from the stomach faster than concentrated drinks, such as cordials, soft drinks, or fruit juice. Drinking small quantities on a regular basis rather than consuming large volumes is also preferable.

The best way to get rid of a stitch? Stop exercising, bend forward, and tighten the abdominal muscles while taking deep breaths. A stitch is rarely a sign of a serious problem and usually passes a few minutes after the person with a stitch stops exercising.

WHAT IS THE HISTORY OF THE PIZZA?

The pizza, in one form or another, has been around for thousands of years. Some claim it is based on pita bread, eaten in the Middle East. Some say that its origin is flatbreads, resembling the modern-day focaccia, which were eaten in ancient times around the Mediterranean. Archaeologists have uncovered structures resembling pizzerias in the remains of Pompeii, which was destroyed in AD 79 by the eruption of Mount Vesuvius. Evidence also suggests that the Greeks brought pizza to Italy in the AD first century. Flat baked breads covered in dressings were also said to be eaten in Rome in 300 BC.

The word pizza, meaning pie, first appeared near Naples and Rome in AD 1000, and it is often accepted that Naples is the origin of the modern-day pizza, with the Neapolitan being the original pizza. The first modern-day pizzeria, which is still in existence, was opened in Naples by Raffaele Esposito in 1830. Pizza was considered food for the poor person, but to honor a visit by King Umberto I and Queen Margherita of Italy, Esposito created a special pizza resembling the Italian flag. The queen was impressed and the Margherita pizza was born.

The pizza was brought from Naples to the United States in 1897 by Gennaro Lombardi, who opened a general store in New York, which sold pizza. The pizzas became so popular that he opened the first American pizzeria in 1905. Called Lombardi’s, the shop still operates today.

In the early 1900s in the United States, pizza was eaten predominantly by immigrant Italians. During World War II, American troops in Italy ate pizza extensively. When they returned, pizza became popular throughout the United States. Pizza shops began opening in the 1950s, and the trend spread quickly. Today, pizza is an international food.

WHAT MAKES DRUGS ADDICTIVE?

Drug addiction is the dependence on a substance to the point where the user feels that he or she must have the drug, regardless of consequences. Addiction varies from drug to drug. Compared with alcohol, it generally takes far less use of heroin to become addicted. Drug addiction also varies from person to person, and some people are genetically predisposed to it. The most common drug addictions are to alcohol, caffeine, and nicotine.

The addiction