Authors: Ira Flatow
Education was what Smith did best. As far back as 1972, in a book and in an article published in that most sacred of all science-teacher magazines, The Physics Teacher, Smith met the enemy wherever he found it. Wherever teachers banked on Bernoulli to teach the theory of flight—in newspapers, in magazines, in a lecture hall—Smith was there to remove Bernoulli from its central role in flight. He called it the “Bernoulli myth” and said it was “the most persistent, pernicious error in school science books.”
Not only is Bernoulli used to explain aircraft lift, Smith lamented, but “I have found articles on ornithology that borrow the error to explain bird-wing lift!”
Smith handed me a copy of one of his magazine articles from The Physics Teacher and asked me to read and see for myself.
“The math is pretty easy for a smart guy like you.”
By now I was more than intrigued. Embarrassed might be a good word. Here I had just lectured to hundreds of people—I was a role model, an author, an “expert”—and now, if Smith was right, I was an idiot. Smith could see my sheepish look, and his smile told me Not to worry; you’ve merely made a mistake common to physics teachers around the world. Join the crowd.
“Just what is the right explanation, then?” I needed to hear his take.
“Very simple: Newton. And his laws of motion. You can easily—and correctly—explain why airplanes fly from first principles. No need to resort to Bernoulli. He was created—really pulled out of a hat—around World War II when the airplane was becoming popular and people wanted a simple explanation. But in reality it takes more time to explain the complicated workings of Bernoulli’s principle than it does the simple laws of Newton. In this case it’s very simple: Airplanes fly because the wing makes the air go down, so the airplane goes up. Action—reaction. Newton’s third law. How hard is that to understand?”
I took Smith’s papers home and read them. They made a lot of sense. I researched Smith and uncovered other articles about him and his quixotic quest to set the record straight. Jerry Bishop, a highly respected colleague of mine and science writing icon of the Wall Street Journal, had come across Smith in 1972 and had written a major Wall Street Journal article about the quest. Being the great journalist that he is, Jerry presented the case but never reached a conclusion. He let the reader decide.
But I was convinced. Of course it was Newton! The beauty of flight was in this detail.
Thus began my own crusade to replace Bernoulli with Newton, just as Smith had tried to do. I soon found and talked with other like-minded science teachers who had begun to make their own contributions. They began to question the very basics of accepted textbook ideas about how air flows over a wing, and they discovered that they were wrong.
I chatted with airplane pilots who had never once relied on Bernoulli to fly. They talked about “angle of attack” and “stalling the wing” and “airspeed” and such. A helicopter pilot showed me his “movable wing” plane—his copter—and told me to take a close look at its shape. He pointed to the end of the wing and said, “Does this look at like your textbook Bernoulli airfoil? Of course not: it’s symmetrical. Contrary to Bernoulli dogma, wings don’t have to be
rounded on top and flat on the bottom. See? Mine are symmetrical, rounded on top as well as bottom. And I’m getting off the ground!”
I decided to take flying lessons to learn the details firsthand. My flight instructor told me that the Federal Aviation Administration (FAA) still requires using Bernoulli’s principle as a teaching aid, despite the growing belief that it’s an inadequate explanation. It’s even on the FAA exam. My flight textbooks and CDs all had Bernoulli. But not once during my training, not on takeoffs or landings, not when recovering from a stall or learning how to “trim for level flight,” did the word Bernoulli come up.
So I knew that in writing this book I had the opportunity to set the record straight. No longer would Bernoulli be the centerpiece of any chapter about why airplanes fly. And for me, a baseball fanatic, there was an even greater injustice: the use of Bernoulli’s principle to explain why a curveball curves or a fastball “rises.” I too bow my head and plead “guilty as charged.” But no longer.
So if the section in this book titled “Why an Airplane Flies: Debunking the Myth” appears more detailed or perhaps more passionate than the others, please bear with me. I’m getting a lot off my chest. I’ve spent almost 15 years thinking about this, and we all know there is no greater crusader than a reformed sinner.
This episode serves as a case in point about another myth: that science knows everything. I’m reminded of the letter I received the first week that Science Friday was on the air in 1991. A woman—let’s call her Barbara from New Jersey—wrote that she had just listened to a program we had broadcast about the extinction of the dinosaurs and the possibility that they had been wiped out by a comet or asteroid hitting the Earth. On that show, a scientist with a competing theory phoned in to say that he disagreed with this new asteroid theory about extinction. The caller got into, shall we say, a frank exchange of views with my guest about their competing theories. They got into a professional “disagreement.” Barbara wrote that she was shocked to hear scientists arguing. She had never heard researchers
disagree. “Isn’t that what science is for? Science knows the truth, doesn’t it?” Imagine that! Scientists arguing! A concept, I think, foreign to most laypeople.
After watching science do its thing for a while, you realize that knowledge is really a moving target. What we know today will probably be wrong tomorrow. And science is that tool for discovery. When science tells us something, chances are that it will tell us something different a few years from now.
And that’s what makes truth stranger than fiction.
A Fox enters the storeroom of a theater. Rummaging through the contents, he is frightened by a face glaring down on him. But looking at it closely he discovers it is only a mask, of the kind worn by actors. “You look very fine,” says the Fox. “It is a pity you haven’t any brains.”
Is it possible to understand our minds? To understand what consciousness is all about? What happens in our brains when we learn or remember? What goes on when we “enjoy” or feel “depressed?”
Understanding the complex biochemistry that turns electrical and chemical energy into thoughts, memories, and feelings is one of the greatest challenges of science. Neuroscience has become “the neurosciences” as genetics, physics and engineering, pharmaceuticals, psychology and psychiatry, and computer science have gotten into the act and contributed to what we know. But the brain is so complex that neuroscientists have a long way to go before we can understand completely how the brain works.
We know that people have been fascinated with the brain for at least 6,000 years. About 4,000 BC, an anonymous writer put down
the very first observations of how the brain works, anticipating The Wonderful Wizard of Oz by noting that eating poppies induced feelings of euphoria and well-being. It seems that people also have always been hitting their heads: The ancient Egyptians documented on papyrus medical treatments for 26 different kinds of brain injury, and pre-Inca civilizations practiced primitive brain surgery, probably for mental illnesses, headaches, or epilepsy. In the Middle Ages, many people witnessed miracles, wonders, and visions—perhaps because they didn’t realize that their brains were tripping on LSD. In 1938, Dr. Albert Hofmann, a distinguished Swiss chemist who was interested in the medicinal properties of plants, was studying the ergot fungus at Sandoz Pharmaceuticals in Basel. He found that ergot contained a kind of lysergic acid with hallucinatory properties, an acid that Hofmann synthesized into LSD for the first time. Ergot fungus often affects grain. In medieval times, grain with the fungus could have been milled into rye bread, causing hallucinations—and along with them, superstitions and religious fervor that could have been due to altered brain chemistry.
Today, we know that the brain runs on electricity—though not the kind of electricity that lights up the lamp over my desk or runs my computer. I’m talking about bioelectricity, which allows the neurons, or cells in the brain, to communicate with one another. Every living cell functions with electricity. When food is digested and turned into blood sugar, or glucose, and dissolves in water inside a cell, its atoms lose or gain electrons. They become free-floating particles called ions, which have either a positive or a negative charge. Since electricity is charge in motion, the movement of charged ions inside a living cell is electricity. When ions move, there is a corresponding shift in charge, an electrochemical change that produces an electric charge, the nerve signal. Every fraction of a second, each nerve cell in the brain and body receives signals that prompt it to respond or not. When a neuron sends a message to another neuron, the signal moves along as a traveling electric pulse. Recently I saw a
photo of a neuron hooked up to a nanoscale plastic circuit on a chip—just one experiment in nanotechnologists’ efforts to build a super-tiny transistor no bigger than a molecule.
While ancient peoples thought that epilepsy was caused by demonic possession, we know that an epileptic seizure is an outward sign of abnormal electrical activity in the brain, due to an imbalance in neural activity that leads to an increase in the rate of neural firing, which can then spread to other parts of the brain. But there are still so many mysteries left, especially how our memories, our hopes and dreams, our intelligence, and everything else we’re thinking of when we say mind are encoded in our brains.
One of the biggest mysteries about the brain is how it begins. When a fetus is only one month old, its first brain cells, or neurons, are growing at the mind-boggling rate of 250,000 neurons a minute. Eventually, those neurons form literally trillions of connections, called synapses, between cells. These connections are well organized, not random: Each neuron finds its correct place in the brain. By the time a baby is born, it has 100 billion neurons, and its brain looks very much like an adult’s. It’s more developed than any other part of the baby’s body, and it’s disproportionately large. After birth, the brain begins to be shaped by environment—the world around the infant and the baby’s experiences. Newborns spend more than 20 percent of their sleep in rapid eye movement (REM) sleep, which some researchers think involves a kind of learning process. Neurologists are studying how the brain shapes itself in response to the demands the environment makes on it. They know the brain changes over a person’s lifetime, as it thinks, controls muscles and limbs, learns, and remembers. The billions of neurons in a person’s brain continually connect and reconnect on many different levels, in response to what their owner does and experiences.
Some of the things we don’t know about the brain are surprisingly
basic. One thing that babies and very young children do a lot is sleep. In fact, they spend half their childhood asleep—and every parent knows how important that is and what their kids can be like if they don’t get their naps. Adults spend about a third of their time asleep, and that doesn’t appear to be an enormous waste of valuable time. Experiments where people have tried to stay awake for as long as 200 hours have induced hallucinations and paranoia. If adults have troubling sleeping—and according to a 2005 poll from the National Sleep Foundation, 57 percent of Americans do—nearly every aspect of their lives is affected, leaving them prone to making mistakes at work, having car accidents, being too sleepy for sex.
Sleep, obviously, offers muscles and other parts of the body a chance to rest. But not the brain: measurements of its electrical activity reveal that it’s hardly dormant. Still, until 1953, when two researchers who were studying children’s sleep patterns described REM sleep for the first time, scientists assumed that the brain was inactive during sleep. But exactly why sleep is so important, regardless of your age, and what sleep means to the brain are questions scientists cannot answer yet. Perhaps sleep helps consolidate learning (more on that later in “Sleep and Learning: Caffeine in Your Beer,” on page 43).
TEENAGERS: WHAT WERE YOU THINKING!
In a child’s first year, the brain triples in size, until it’s almost three quarters of the size of an adult’s. The brain achieves its full growth at about age 17. The number of neurons doesn’t increase, but the number of synapses do as children imitate, learn, remember, and add to their experiences. By adulthood, the brain has 100 trillion synapses. But before adulthood comes adolescence, when the brain is flooded with hormones. Neurologists only recently have confirmed what every parent knows: The teenage brain is indeed different. In the teenage brain, the prefrontal cortex—the center of reasoning and impulse control—is still forming. In some people, that maturation may not
occur until they are 25 years old. That’s why so many teenagers have trouble understanding the consequences of their impulsive, destructive behavior. That’s why, as every parent can tell you, teenagers are impulsive, emotionally erratic, and liable to make poor decisions. The answer is simple: The section of the brain that can foresee the future, the part that can predict the consequences of actions, is not fully developed.
Every parent also knows that teenagers have a terrible time getting up in time for school and on weekends, preferring to sleep into the afternoon. Neuroscientists now know that teens aren’t being lazy—they really do need more sleep. Some schools have even pushed the start of the school day later to take into account the adolescent need for sleep.
SEEING INSIDE THE BRAIN
We’ve been able to learn more about the adolescent brain because today, we don’t have to drill into the brain to find out about it, as early peoples did. We have new technology that allows us to see what the brain looks like and what it’s doing. And that’s an excellent advance because the brain is delicate, and once a neuron is destroyed, it’s gone forever—though the brain often is able to compensate for the loss. Neurosurgeons even have a pithy saying: “You’re never the same once air hits your brain.”