When Do Fish Sleep? Part 12

If a pneumatic drill is making a ruckus outside your window, you have a few choices. One is to do nothing, which won't accomplish much until the drill stops. But another option is to go to your stereo and put on a Led Zeppelin record at full blast. The pneumatic drill is still just as loud-you may still even be able to hear it. But the music will certainly distract you (and for that matter, your next-door neighbors as well), so the drilling doesn't seem as loud.

Hooker emphasizes that most of us a.s.sociate warmth with pleasant experiences from our youth. By placing heat on the part of our body that hurts we stimulate the sensory receptors, which tell our brain that there has been a temperature change. This doesn't eliminate the pain, but the distraction makes us less aware of the pain. As our body accommodates to the high temperature, we need fresh doses of warmth to dampen the pain. When we receive the renewed heat treatment, we expect to feel better, so we do.

Why Can't We Use Both Sides of a Videotape like We Do with an Audio Tape?

Don French, chief engineer of Radio Shack, is getting a little testy with us: "If you keep using me as a consultant on your books, we are going to have to start charging for my service!"

We have read all of the bestselling business management books. They all reiterate that most people aren't motivated by higher pay but by recognition of their effort and accomplishments. So to you, Don French, we want to acknowledge our heartfelt appreciation for the efforts you have expended in educating the American public on the wonders and intricacies of modern technology in our contemporary culture of today. Through your efforts, our citizens will be better equipped to handle the challenges and complexities of the future.

But not one penny, bub.

Luckily, Mr. French couldn't resist answering this Imponderable anyway.

It turns out that even though some audio ca.s.sette recorders require the tape to be flipped before recording on the other side, the recorder doesn't actually copy on both sides of the tape. It copies on the top side of the tape in one direction and the bottom in the other direction.

On videotapes, the audio is also recorded on a small portion of the top side of the tape. But the video, with a much higher frequency requirement and slower recording speed, needs much more room to copy, and is recorded diagonally on most of the remaining blank tape.

Submitted by Jae Hoon Chung of Demarest, New Jersey.

Why Are the Toilet Seats in Public Restrooms Usually Split Open in the Front?

This has become one of our most frequently asked Imponderables on radio shows. So for the sake of science and to allay the anxiety of unspoken millions, here's the, pardon the expression, p.o.o.p on a mystery whose answer we thought was obvious.

Try as they might, even the most conscientious janitors and bathroom attendants know it is impossible to keep a multiuser public toilet stall in topnotch sanitary condition. Let's face it. Pigs could probably win a slander suit from humans for our comparing our bathroom manners to theirs. Too many people leave traces of urine on top of toilet seats. Men, because of a rather important physiological distinction from women, particularly tend not to be ideally hygienic urinators, but most sanitary codes make it mandatory that both male and female toilets contain "open-front" toilet seats in public restrooms. In fact, at one time, "open-back" seats were mandated as well, but the public wouldn't stand (or sit) for them.

If they are more hygienic, why not use open-front toilet seats at home? The answer is psychological rather than practical. An open-front seat would imply to the world that one's bathroom habits were as cra.s.s as those employed by the riffraff who use public restrooms. Still, we would think that open-front toilet seats in home bathrooms might lessen the number of divorce-causing arguments about men keeping the toilet seats up.

Submitted by Janet and James Bennett of Golden, Colorado. Thanks also to Tom Emig of St. Charles, Missouri; Kate McNeive of Scottsdale, Arizona; and Tina Litsey of Kansas City, Missouri.

How Are the First Days of Winter and Summer Chosen?

This Imponderable was posed by a caller on John Dayle's radio show in Cleveland, Ohio. John and the supposed Master of Imponderability looked at each other with blank expressions. Neither one of us had the slightest idea what the answer was. What did it signify?

We received a wonderful answer from Jeff Kanipe, an a.s.sociate editor at Astronomy. His answer is complicated but clear, clearer than we could rephrase. So Jeff generously has consented to let us quote him in full: The first day of winter and summer depend on when the sun reaches its greatest angular distance north and south of the celestial equator.

Imagine for a moment that the Earth is reduced to a tiny ball floating in the middle of a transparent sphere and that we're on the "outside" looking in. This sphere, upon which the stars seem fixed and around which the moon, planets, and sun seem to move, is called the celestial sphere. If we simply extend the earth's equator to the celestial sphere it forms a great circle in the sky: the celestial equator.

Now imagine that you're back on the Earth looking out toward the celestial sphere. You can almost visualize the celestial equator against the sky. It forms a great arc that rises above the eastern horizon, extends above the southern horizon, and bends back down to the western horizon.

But the sun doesn't move along the celestial equator. If it did, we'd have one eternal season. Rather, the seasons are caused because the Earth's pole is tilted slightly over 23 degrees from the "straight up" position in the plane of the solar system. Thus, for several months, one hemisphere tilts toward the sun while the other tilts away. The sun's apparent annual path in the sky forms yet another great circle in the sky called the ecliptic, which, not surprisingly, is inclined a little over 23 degrees to the celestial equator.

Motions in the solar system run like clockwork. Astronomers can easily predict (to the minute and second!) when the sun will reach its greatest angular distance north of the celestial equator. This day usually occurs about June 21. If you live in the Northern Hemisphere and note the sun's position at noon on this day, you'll see that it's very high in the sky because it's as far north as it will go. The days are longer and the nights are shorter in the Northern Hemisphere. The sun is thus higher in the sky with respect to our horizon, and remains above the horizon for a longer period than it does during the winter months. Conditions are reversed in the Southern Hemisphere: short days, long nights. It's winter there.

Just reverse the conditions on December 22. In the Northern Hemisphere, the sun has moved as far south as it will go. The days are short, while the lucky folks in the Southern Hemisphere are basking in the long, hot, sunny days.

The first days of spring and fall mark the vernal and autum nal equinox, when the sun crosses the equator traveling north and south. As astronomer Alan M. MacRobert points out, the seasonal divisions are rather arbitrary: Because climate conditions change continuously, there is no real reason to have four seasons instead of some other number. Some cultures recognize three: winter, growing, and harvest. When I lived in northern Vermont, people spoke of six: winter, mud, spring, summer, fall, and freezeup.

Why Do Most Cars Have Separate Keys for the Ignition and Doors? Doesn't This Policy Increase the Chances of Locking Yourself Out of the Car?

The automakers aren't so concerned about you getting into your car. They are worried about thieves getting into your car.

Ford Motor Company, for example, now uses one key for the ignition and doors and a separate key for the glove compartment and trunk. Ford once used the same key for the door and the trunk, but changed. A Ford representative, Paul Preuss, explains: At one time, it was a relatively easy matter for a car thief to work open a car door and make an imprint so that it was possible to produce a key that also worked the ignition. Hence, a separate ignition key. Changing from a five-cut key to the present ten-cut key accomplishes the same thing. Five of the cuts activate the door lock and a different five operate the ignition. Taking an imprint of the door lock does not provide the proper cuts for the ignition lock.

General Motors also provides a separate key for doors and ignition and explains its decision as an attempt to foil aspiring thieves.

A two-key approach also allows the car owner to stash valuables in the trunk or glove compartment while leaving only the ignition key with a parking lot attendant or valet. And if you misplace the door key? Well, there's always the coat hanger.

Submitted by Doris Hosack of Garfield Heights, Ohio. Thanks also to Charles F. Myers of Los Altos, California; and Loretta McDonough of Frontenac, Missouri.

P.S. News Flash. Just as this book was going to press, we received a note from the Ford Parts and Service Division. Although the company felt that separate door and ignition keys made sense for security reasons, Ford is returning to its roots: "The consumer prefers one key for both door and ignition; therefore, we will phase in one key for both in the near future."

What's the Difference Between Popcorn and Other Corn? Can Regular Corn Be Popped?

There are five different types of corn: dent, flint, pod, sweet, and popcorn. Popcorn is the only variety that will pop consistently. Gregg Hoffman, of American Popcorn, told Imponderables that other corn might pop on occasion but with little regularity.

The key to popcorn's popping ability is, amazingly, water. Each popcorn kernel contains water, which most popcorn processors try to maintain at about a 13.5% level. The water is stored in a small circle of soft starch in each kernel. Surrounding the soft starch is a hard enamel-like starch. When the kernel is heated for popping, the water inside heats and begins to expand. The function of the hard starch is to resist the water as long as possible.

When the water expands with such pressure that the hard starch gives way, the water bursts out, causing the popcorn kernel to explode. The soft starch pops out, and the kernel turns inside out. The water, converted into steam, is released (fogging the eyegla.s.ses of four-eyed popcorn makers), and the corn pops.

The other four varieties of corn are able to store water effectively. But their outer starch isn't hard enough to withstand the water pressure of the expanding kernel, and so nothing pops.

Submitted by David Andrews of Dallas, Texas.

What Does It Mean When We Have 20-20 or 20-40 Vision?

The first number in your visual acuity grade is always twenty. That's because the 20 is a reference to the distance you are standing or sitting from the eye chart. The distance is not a coincidence. Rays of light are just about parallel twenty feet from the eye chart, so that the muscle controlling the shape of the lens in a normal eye is in a state of relative rest when viewing the chart. Ideally, your eyes should be operating under optimal conditions during the eye test.

The second number represents the distance at which a normal eye should be able to see the letters on that line. The third from the bottom line on most eye charts is the 20-20 line. If you can see the letters on that line, you have 20-20 ("normal") vision. A higher second number indicates your vision is subnormal. If you have 20-50 vision, you can discern letters that "normal" observers could see from more than twice as far away, fifty feet. If you achieve the highest score on the acuity test, a 20-10, you can spot letters that a normal person could detect only if he were 50% closer.

We also got the answer to another Imponderable we've always had about the vision test: Are you allowed to miss one letter on a line and still get "credit" for it? Yes, all you need to do is identify a majority of the letters on a line to get full credit for reading it. If only our schoolteachers were such easy graders.

How Does Yeast Make Bread Rise? Why Do We Need to Knead Most Breads?

Yeast is a small plant in the fungus family (that's ascomycetous fungi of the genus Saccharomyces, to you botanical nuts), and as inert as baker's yeast might seem to you in that little packet, it is a living organism. In fact, it works a little like the Blob, feeding and expanding at will.

Yeast manufacturers isolate one healthy, tiny cell, feed it nutrients, and watch it multiply into tons of yeast. One gram of fresh yeast contains about ten billion living yeast cells, thus giving yeast the reputation as the rabbit of the plant world.

To serve the needs of bakers, manufacturers ferment the yeast to produce a more concentrated product. But the yeast isn't satisfied to idly sit by in the fermentation containers-it wants to eat. So yeast is fed its favorite food, mola.s.ses, and continues to grow. A representative of Fleischmann's Yeast told Imponderables that under ideal conditions, one culture bottle of yeast holding about two hundred grams will grow to about one hundred fifty tons in five days, enough yeast to make about ten million loaves of bread.

After it has grown to bulbous size, the yeast is separated from the mola.s.ses and water and centrifuged, washed, and either formed into cakes or dried into the granulated yeast that most consumers buy. When the baker dissolves the yeast in water, it reactivates the fungus and reawakens the yeast's appet.i.te as well.

Yeast loves to eat the sugar and flour in bread dough. As it combines with the sugar, fermentation takes place, converting the sugar into a combination of alcohol and carbon dioxide. The alcohol burns off in the oven, but small bubbles of carbon dioxide form in the bread and are trapped inside the dough. The carbon dioxide gas causes gluten, a natural protein fiber found in flour, to stretch and provide a structure for the rising dough without releasing the gas. When the dough doubles in size, the recommended amount, it is full of gas bubbles and therefore has a lighter consistency than breads baked without yeast.

By kneading the bread, the baker toughens the gluten protein structure in the dough, stretching the gluten sufficiently to withstand the pressure of the expanding carbon dioxide bubbles. You don't need to knead all dough, however; for instance, batter breads, which are made with less flour and have a more open, coa.r.s.e grain, don't need it.

Submitted by Jim Albert of Cary, North Carolina.

Why Do Doctors Tap on Our Backs During Physical Exams?

We've always been suspicious about this tapping. From a patient's point of view, it has two strong attributes: It doesn't hurt and it doesn't cost anything extra. But nothing ever seems to happen as a result of the tapping. No doctor has ever congratulated us on how great our back sounded or for that matter looked worried after giving us a few whacks on the back. At our most cynical, we've even wondered whether this is a physical examination equivalent of a placebo: The doctor gets a break from the anxious gaze of the patient, and the patient is rea.s.sured that at least the back part of his body is O.K.

Doctors insist that there is a sound reason to tap our backs. Short of an X ray, the tap is one of the best ways to collect information about the lungs. The s.p.a.ce occupied by the lungs is filled with air. The two lungs are contained in the two pleural s.p.a.ces, full of air, and lung tissue itself contains air.

Dr. Frank Davidoff, a.s.sociate executive vice president, Education, for the American College of Physicians, told Imponderables about the fascinating history of the practice of tapping: In 1754, a Viennese physician named Leopold Auenbrugger discovered that if you thumped the patient's chest, it would give off a more hollow sound when you tapped over the air-filled lung s.p.a.ce, and a more "flat" or "dull" sound if you tapped over a part of the chest that was filled with something more solid, like muscle, bone, etc. Auenbrugger's father was a tavern keeper in Graz, Austria, who used to judge the amount of wine left in the casks by tapping on them-the hollow note indicating air, the flat note indicating wine.

Auenbrugger found that by thumping a patient's chest-somewhat as his father rapped on a cask-abnormal lesions in the chest cavity, such as fluid or a solid tumor in the cavity where air-filled lung ought to be, produced a sound different from that given off in a healthy air-filled chest. Auenbrugger tested out his new method of physical diagnosis over a period of seven years of drumming on his patient's chests, and in 1761, he put before the medical profession the result of his experiments, in a book called New Invention to Detect by Percussion Hidden Diseases in the Chest.

Dr. Davidoff adds that the technique used today is virtually the same as the one Auenbrugger invented more than two hundred years ago.

Dr. William Berman, of the Society for Pediatric Research, says that the technique is a good, obviously cheap alternative to an X ray and has even other attributes. Tapping on the front of the chest can determine the size of a patient's heart, because the heart is much more solid than the lungs as it is muscular and full of blood.

Submitted by Richard Aaron of Toronto, Ontario.

Why Do Military Personnel Salute One Another?

Every Western military organization we know of has some form of hand salute. In every culture, it seems the inferior initiates the salute and is obligated to look directly into the face of the superior.

The origins of the hand salute are murky. In ancient Europe, where not only military officers but freemen were allowed to carry arms, the custom for men about to encounter one another was to lift their right hand to indicate they had no intention of using their sword. Many of our friendly gestures, such as tipping hats, waving, and handshaking, probably originated as ways of proving that one's hand was not reaching for a sword or a convenient rock.

By the time of the Roman Empire, salutes were a part of formal procedure among the military. Soldiers saluted by placing their right hands up to about shoulder height with the palm out. The hand never touched the head or headgear during the salute.

In medieval times, when knights wore steel armor that covered their bodies from head to toe, two men often encountered each other on horseback. To display friends.h.i.+p, two knights supposedly would raise their visors, exposing their faces and ident.i.ties to view. Because they held their reins in the left hand, they saluted with their right (sword) hand, an upward motion not unlike the salute of today.

Whether or not our modern salute stems from the rituals of chivalry, we know for a fact that we Americans borrowed our salute from modern British military practices. In 1796, British Admiral Earl of St. Vincent commanded that all British officers must henceforth take off their hats when receiving an order from a superior "and not to touch them with an air of negligence." Although the British Navy made salutes compulsory, it didn't codify the precise nature of the salute. In many cases, inferiors simply "uncovered" (doffed their caps).

The American military salute has also undergone many changes over the years. At one time, Marines didn't necessarily salute with their right hand, but the hand farthest from the officer being saluted. Even today, there are differences among the branches. Although the Army and Air Force always salute with their right hand, Navy personnel are allowed to salute with the left hand if the right is enc.u.mbered. And while Air Force and Army men and women may salute while sitting down, Naval officers are forbidden to do so.