The inventor has a logical mind that sees analogies.
—THOMAS EDISON
ANYONE WHO HAS TAKEN a standardized aptitude test is familiar with the trick of completing analogies. Pipe is to water as wire is to what? If you are smart or lucky enough to eliminate the silly choices from a given list of options and end up with “electricity” as your answer, you get one point on the test. Inventors, however, must extend this ability to analogize by a couple of giant steps. Instead of simply completing analogies, they must create new ones and then apply them to the problems they are trying to solve.
Inventors are fueled by the analogies that they spot all around them. Applying an analogy is a process of spotting knowledge in one context that can be abstracted and transferred to another context. Inventors are particularly skilled at this kind of context shifting, but virtually anyone can do it once he or she recognizes the pattern. Typically, analogies shift from the world of the familiar, which is called the knowledge “base,” to the new picture of a new invention, which is called the invention “target.” Analogies, in other words, suggest solutions.
Woody Norris was searching for an analogy to help him slay an elusive problem. In 1988, he was running American Technology Corporation, his San Diego invention shop. He was brainstorming a way to eliminate speakers from audio systems when he realized that what he needed above all else was an apt comparison to the problem he had created in his mind. “By this time in my life, I had figured out how you invent things,” he says. “Here is the key: You invent by analogy. Nature, science, chemistry, pick your field. Almost everything in those fields has an analogy to something else.”1
Before he could spot an accurate correlation, Norris had to pare the problem to its essence. “There were two parts to the hi-fi systems that were still crude and mechanical,” he says. “One was the mechanical needle in the groove of a record, which has since been replaced. The other was the speaker, which is this mechanical piston vibrating back and forth and bumping air molecules to make sound.” Even the best speakers are subject to distortion, he says. “It’s the weak link. Everything else is electronic.”
He asked himself a radical question: Can I eliminate the speaker? “Why don’t I figure out how to make the sound in the air? Then I’d have theoretically perfect sound.” Making sound in the air? What’s analogous to that? “I started picking my brain,” he recalls. “What I was looking for is something that is done in one area that might help me solve a problem in another.”
By now, Norris was invoking analogies to understand almost everything he knew about electronics. “I’ll give you an easy one,” he says. Most people don’t understand how electricity is made. But when shown the proper analogy, they finally see what Michael Faraday accomplished in 1831. Picture a giant spring suspended from the ceiling, with a weight attached to the lower end. “The spring will vibrate with a certain resonance,” Norris says. That reverberation is energy, pure and simple. “If you know something of the nature of the spring and the weight, you can have a simple formula for how it will resonate. In electronics, the coil is called an inductor, and the capacitor is like the weight. The same circuit that works for electricity also works for mechanical resonance. That’s the analogy.”
To conceive of his invention in the hi-fi realm, Norris lifted an analogy from the world of art. “When an artist takes a palette with six or eight colors on it, she can mix new colors,” he says. He realized that this mixing metaphor could be applied to the problem: “To create sound in the air, I’d have to mix together different frequencies to create new ones.”
A similar analogy had already been demonstrated in the world of video. A color television set, for example, can produce only three primary color frequencies: those of red, green, and blue. But the electronic mixer inside the set can blend these three colors to create the millions of combinations that we see on the TV screen. Applying the same analogy, Norris figured that “there ought to be a way to mix sound frequencies in the air and get new ones. I knew mixing worked in electronic circuitry, and I knew it worked optically. Why wouldn’t it work sonically? That was the inspiration. I began to see mixers everywhere.”
From his earlier invention, Norris already understood ultrasound, the electromagnetic waves that beat at more than 20,000 cycles per second (hertz), too frequent for the human ear to hear. What if you mixed different frequencies of ultrasound waves? “If I mixed 100,000 cycles with 101,000 cycles, could I get the 1,000-cycle difference?” Such a frequency can indeed be processed by the human ear, which can decode sound in the ranges of 20 to 20,000 cycles per second. (Dogs have a slightly higher range, explaining the “silent” dog whistle.)
Following the logic of his analogy, Norris’s question became this: Could you mix sounds that you couldn’t hear to produce sounds that you could hear? The answer, as Norris puts it: “Absolutely! Unequivocally! Yes!” Instead of mechanically vibrating air molecules, Norris believed that he could produce sound in midair by using mathematical combinations of ultrasonic waves.
When he first tested his analogy, however, nothing worked. He pointed a pair of ultrasound emitters in such a way that the beams crossed paths. He tried all kinds of combinations of frequencies. Instead of producing sound, this arrangement produced only silence. Eventually, he was able to produce faint sounds in this way, but his theory wasn’t proving itself very useful in practice.
Still, Norris was so confident in his analogy that he persisted. Giant companies, among them Sony, Motorola, and AT&T’s Bell Laboratories, had already been down a similar path, and when they failed to harness ultrasound for this purpose, they gave up—something Norris found out years after his own attempt began. “Not that I’m smarter than them,” Norris says. “They gave up, in part because of the lack of appropriate materials at the time, but mainly because they didn’t know for sure during the process that it could be done. Often, if you don’t know something can be done, it doesn’t take a lot to get you to quit.” Norris even persisted when his own engineering staff expressed doubts that his invention would ever produce sound that was as loud as that produced by traditional speakers.
To get his system to work, Norris increased the amplitude of his ultrasonic waves to levels that others had not tried, and he tinkered with various sound combinations and audio-processing techniques. “It took me seven years to simplify it, pull all the distortion out of it, and bring up the efficiency,” he says. “But I had no doubt that it would work.” Total investment in developing and patenting the invention has so far exceeded $40 million.
The resulting product, the HyperSonic Sound (HSS) system, is a set of electronic components that converts sound from a CD player or other audio source into patterns of ultrasonic waves. The waveforms are fed through an electronic mixer, acting as a painter’s palette, which in turn sends the waves through an ultrasonic amplifier that powers a set of emitters. The emitters are thin silvery films, typically made from aluminum, that send the silent, high-frequency waves into the air. When two or more of these silent waves interact and interfere with one another, they produce new sounds, in much the same way that a cacophony of voices in a noisy restaurant mix together, augment one another, or cancel one another out. “If you know how the air itself affects the sound waves,” Norris explains, “you can predict what new frequencies will be added into the sound wave by the air.”
Once again, an inventor was invoking the work of Hermann von Helmholtz, the German physicist who inspired Alexander Graham Bell. When playing two notes very loudly on a pipe organ, von Helmholtz noticed faint third and fourth tones resonating in the air—one at a higher frequency than the original notes, and the second at a lower frequency. He proved that the resistance of the air itself was producing this distortion effect. In doing so, he was well on the way toward invoking one of the greatest analogies of all time: that all matter is like all other matter. The air is like water. Water is like flesh. Flesh is like rock. Rock is like the moon. The moon is like the stars. The stars are like air. All are made of molecules that experience resonance in different ways.
For his part, Woody Norris knew that if he worked his sonic mixing palette just right, he could resonate the air so that it would produce these new frequencies. As a result, his HSS system has no speaker cones, no tweeters, no midrange diaphragms, and no woofers; instead, it has only a pair of thin films that serve as the ultrasound emitters.
Norris knew it would take him years to perfect his invention, but he also knew that his analogy was rock solid. “You can take great comfort if you are confident your analogy is valid,” he says.
As you’ll see later in this chapter, Norris applied an entirely different analogy to understand and define the dozens of unexpected applications for HyperSonic Sound. But before we get to that, let’s take a look at other recent and classic cases in which inventors achieved breakthroughs by applying analogies.
Like many thinking strategies, the spotting of useful analogies is an inventive behavior that typically reaches back into childhood. James McLurkin developed a knack for analogizing while growing up on Long Island. McLurkin is an articulate, young African American inventor, with closely cropped hair and a thin mustache. As a kid, he was bored by school and was constantly told he was not working up to his potential. Instead of focusing on his schoolwork, he spent much of his time constructing imaginary worlds. He went from Legos and erector sets to model train sets to radio-controlled car kits to designing his own computer video games. He also spent hours with his family watching science, nature, and animal TV shows, and that led him to make connections between the natural world and his own world of physical materials.
As a student at MIT in the late 1990s, McLurkin began building hand-sized robots, known as “swarm robots,” that simulated behaviors found in the occupants of ant colonies and beehives. Using sensors to detect one another, actuators to control motion, and infrared beams to coordinate communication, the robots performed functions by picking up signs from their teammates and their surroundings. He was getting in on the ground floor of the new field of “biomimetics,” the science of designing technology that draws analogies from the natural world. “Nature is the best engineer we know about,” McLurkin says.2
McLurkin shares credit for his invention with mentors who are also steeped in biological analogies. Foremost among them is Rodney Brooks, the director of the MIT Computer Science and Artificial Intelligence Laboratory. Brooks has changed the field of robotics and artificial intelligence (AI) by replacing the “top-down” approach with a “bottom-up” philosophy. Instead of trying to build human knowledge and rules of reasoning into software, he has pioneered the idea that the perception of intelligence can emerge from lots of relatively dumb components interacting with one another. Ant colonies and bee swarms are just two examples.3 To put some of his ideas into action, Brooks cofounded iRobot, a Somerville, Massachusetts, developer of consumer robot devices such as the Roomba, an autonomous vacuum cleaner. Brooks encouraged McLurkin to study other natural systems and apply the resulting analogies to McLurkin’s own set of robots. This central idea—that complex behavior can emerge from the interaction of simple beings—became one of the core analogies put into practice at iRobot.
While completing his Ph. D. at MIT, McLurkin became the lead scientist on the Swarm Robotics Project at the company. Soon, McLurkin’s intelligent swarm grew to more than one hundred robots. The inventor equips his robots with food sensors, trail sensors, and cameras. Future applications range from locating land mines to patrolling chemical plants and other sensitive security zones to exploring terrain on other planets. It’s all part of what McLurkin calls his “biologically inspired mind-set.”
When McLurkin accepted the Lemelson-MIT Student Prize for Inventiveness in 2003, which came with a $30,000 grant, he brought his robot swarm to the Boston Museum of Science for a demonstration. Each of the microrobots looked like a Nintendo game cube with set of red, green, and yellow lights mounted on top. Individually, the robots couldn’t do very much. But McLurkin commanded them with a remote control to exhibit collective behaviors. For example, the “orbit” command had the robots moving in a circle, a behavior that could be used to help secure a large perimeter in a war zone. The “dispersion” command had the robots spreading out in different directions, a behavior that can be used for exploring a mine field or a lunar surface. When he commanded the lead robot to “cluster” his friends, the followers gathered tightly in a small space. McLurkin was also able to get the robots to perform synchronized dance routines. As the demonstration wore on, groups of kids on field trips kept gathering around the railings that overlooked the stage, watching in wonder.
McLurkin’s swarm of robots is but one example of biomimicry. Nature is not only an engineer, in the Darwinian sense, but also a source of ideas for a diverse range of industries, especially the medical field. A case in point is the work of Jay Vacanti, a doctor and research scientist at the Harvard Medical School. While on vacation one summer, Vacanti came across a simple analogy for a complex concept. He had been thinking about the possibility of simulating human skin in the laboratory. Like other medical researchers, he saw the need to grow skin for grafting, for medical testing, and for creating new anticancer treatments.
The solution came to Vacanti in the summer of 1986 while he was relaxing on a beach in Cape Cod. He was watching seaweed float in the surf when he thought to get up and take a closer look at it. When he observed the intricate branch structure in the flesh of the seaweed, it struck him that mimicking such a structure in lab-grown skin would be the perfect way to bring oxygen and other nutrients to the skin culture as it grew. He ran the idea by Robert Langer, a colleague and a renowned inventor from MIT’s bioengineering division. Langer happened to be looking for a similar solution. The two agreed to collaborate. They ended up pioneering the field of human tissue engineering, which is now a multibillion-dollar market with dozens of cutting-edge medical applications. Thus, seaweed ended up providing the clue needed to create artificial tissues and organs.4
This behavior—of moving from base to target and sometimes back and forth repeatedly—reaches far back into history. Leonardo da Vinci, for example, observed that birds, when they spread their wings, used the air as a “wedge to raise them up.” He used the mechanical concept of a wedge as the base to understand behavior in the natural world. In turn, he used the flight of birds as the base to conceive of his target: a flying machine. Brainstorming an example of a rotating wedge, da Vinci conceived of a mechanical analogy: that of a screw boring into wood, lifting material out of the way as it turns. From that observation, he conceived of an “air screw.” His famous sketches of a helicopter-like apparatus feature screw-like rungs lifting a cone-shaped basket into the air. “If this instrument made with a screw . . . [is] turned swiftly,” he wrote, “the said screw will make its spiral in the air and it will rise high.”5
Da Vinci’s conception of an air screw as a flying machine was unworkable, but it was a breakthrough analogy nonetheless. It would be left to future inventors to conceive of an even better analogy, that of a rotary wing, a concept that led to the development of the propeller.
Johannes Gutenberg, by contrast, was able to put his analogy into practice. Gutenberg, a fifteenth-century German metalworker, was searching for a system for mass-producing the Bible. At that time, monks hand-carved wooden plates for each page they wanted to print. They inked the plate, laid a piece of paper on it, and rubbed it until an impression was made. It beat copying manuscripts by hand, but it wasn’t an efficient way to reproduce books. Although the Chinese are known to have invented movable type earlier, Gutenberg didn’t know about it. He set out to reinvent aspects of printing, as often happens in the world of invention.
In his revolutionary creation of a printing press, Gutenberg applied two analogies. He took the first one from the stamps and wax seals used for embossing emblems or characters on paper. He saw that if he were to line up many of these stamps in rows, he’d be able to rearrange and reuse them. When he miniaturized the characters and fashioned them out of metal that could be positioned in rows, he became the first European known to create movable type.
What remained was to replace hand rubbing with a way of rapidly printing page after page from the same plate. Gutenberg stumbled into this more interesting analogy at a wine festival. There, amid the drunken revelry, he saw a hand-cranked winepress that was used to extract juice from flat beds of grapes. That was the inspiration for creating a hand-cranked machine that rapidly pressed blank pages against a flat bed of easily arranged characters.6 Nearly six centuries later, we use that analogy every time we refer to the media as “the press.”
Gutenberg’s isn’t the only media invention that originated from analogies that recall the world of agriculture. Before the days of radio, for example, broadcasting was a farm term that referred to scattering seeds in all directions at once in an effort to cover as much area as possible and yield a rich crop.
Television as we know it is also based on a farming analogy. Philo T. Farnsworth lived with his family on an Idaho potato farm. In 1921, as a fourteen-year-old, he read in science magazines about radio and about predictions that someday it would be possible to send images through the airwaves. No one had been able to do it, and Farnsworth set out to find a solution.
Others had tried to create mechanical television systems, but Farnsworth, reading about Einstein’s Nobel Prize–winning photoelectric theory, was inspired to seek a solution based on the relationship between electricity and light. One day, while plowing the potato field, he glanced back at the parallel furrows and envisioned a process of using electrons to scan and reassemble moving images line by line. Keeping this analogy alive in his mind, Farnsworth built and patented the world’s first electronic television system six years later.7 In other words, the potato field led to the couch potato.
Analogies and metaphors often form the basis of scientific understandings that lead directly to invention. Benjamin Franklin, for example, saw the mysterious force of electricity as directly analogous to lightning. The analogy that aided the conception of the artificial heart was to see the heart as a specialized kind of pump. Molecular biologists such as Leroy Hood view proteins as building blocks that can form a huge variety of structures. Analogies between the mind and the computer have long pervaded both computer science and cognitive science.
Analogy is also at the heart of patent number 4,490,728, which was filed by an inventor named John Vaught and assigned to his employer, Hewlett-Packard.8 Vaught knew well the limitations of the available inkjet printers, which worked by vibrating toner out of a cartridge and onto the paper. Although the output quality was low, inkjets cost about the same as high-end laser printers. One morning in 1979, Vaught was making coffee when he began taking a close look at the coffee machine. He noticed how quickly and efficiently the machine employed heat to percolate the water, and he wondered whether he could use heat to do the same with printer ink. Perhaps a printer could be built like a coffee machine. The analogy led to one of the most valuable patents in the modern history of computers.9
At about the same time, a rival engineer at Canon in Japan came across the same technique by accident. He dropped a soldering iron onto an ink cartridge and thought of the same thing when the heat of the iron began acting on the ink. The Canon engineer also filed a patent on the idea. But instead of competing with each other, H-P and Canon included the new heat-activated, “thermal” inkjet technology in their already formidable alliance. The two companies cornered the market on low-cost computer printers for the next twenty years.
In one of the all-time most brilliant shifts from base to target, Niels Bohr applied the Copernican understanding of the solar system to a model of the atom. The nucleus is analogous to the sun, Bohr said. The orbiting electrons, in turn, are analogous to the planets.
Although this analogy remains vivid and useful, other analogies have refined and in some ways refuted Bohr’s model. Max Planck wondered why electrons sometimes seemed to jump to different orbits. Such jumps produced energy, which were measured in photons, or “quanta,” of light. In his conception of quantum theory, Planck compared electron orbits to waves. Louis de Broglie, a violinist, took this analogy even further. He compared the orbits of electrons to strings that resonated, much like the strings of a violin. When physicists invented instruments that were able to listen to and measure this atomic resonance, de Broglie’s “string theory” was confirmed.10 As a result, he joined Bohr and Plank as a winner of the Nobel Prize in physics.
This concept—that energy can be used to produce resonance in all types of matter—has led to numerous inventions. Foremost among them is MRI (magnetic resonance imaging), a method of vibrating the matter inside the body to create precise image maps of internal organs.
Conveniently, the violin analogy leads us back to the story of Woody Norris and his invention of HyperSonic Sound. His analogy of using ultrasound energy to resonate air molecules is essentially the same one that led to the invention of the MRI. “Everything has a resonance,” says Norris.11
But Norris also applied a second analogy from the domain of light to the sphere of sound. The analogy was a beam of light, such as a beam from a flashlight or from a laser gun. When you are in a dark room and shine a flashlight at a wall, the beam illuminates the dust particles in the air and creates a spot on the wall, but the area outside the beam remains dark. This is the simple principle behind a spotlight. The more intense the light, the more focused the beam. Norris had learned that ultrasound waves work in the same way. The higher the frequency of the ultrasound waves, the more “directional” the waves become. Whereas sound from a speaker will scatter to the far corners of a room, ultrasound waves are like laser beams of sound.
In other words, ultrasonic energy is highly directional. These high-frequency sound emissions form a column of sound in front of the emitter, much like light from a laser. The electromagnetic energy exists only inside that column and doesn’t spread in all directions. As Norris puts it, it’s “locked tightly inside.”
Applying this insight, Norris postulated that the sounds he would be mixing in the air might be heard only by ears located within the beam. If you were outside the beam, you’d hear nothing. The sound beam would also be able to travel much greater distances than traditional sound waves, and it could be redirected by bouncing it off of solid surfaces, just as a flashlight beam in a dark room will bounce off the wall. “You can hear the spot of sound,” explains Norris. “And with two channels, one for the left and one for the right, you get stereo sound.” Norris isn’t the only inventor who has been driven by this analogy between focusing light and focusing sound. F. Joseph Pompei, a graduate student who led a research project on directional sound at the MIT Media Laboratory, has applied the same analogy to come up with a remarkably similar invention that he calls the Audio Spotlight. While completing his Ph. D., Pompei started Holosonic Research Labs in Watertown, Massachusetts. The two inventors are now locked in a head-to-head battle for what they both believe is a billion-dollar market.12
The analogy to the flashlight, spotlight, or laser beam suggested an endless array of applications to both inventors. Sound from a computer could be directed only at the user without disturbing coworkers in an office. Museum exhibits could talk only to those who stand in front of a painting. Those in the front seat of a car could listen to one type of music while those in the backseat would listen to another, without the need for headphones. Conference speeches could be translated into different languages, and audience members could sit in the section whose beam generates the speech in their native tongue. Vending machines could speak to people passing by, perhaps making special sales pitches. Fast-food restaurant displays, department store clothing racks, grocery store products, and trade show booths could do the same thing. The sound would feel as if it were inside your head, and a person only a few feet away wouldn’t hear it.
With home entertainment systems, you could deflect sound off walls rather than wire the speakers throughout a large room. Being able to control the sound dispersion area could also change concert-hall acoustics by eliminating the dreaded problem of feedback from amplifiers into live microphones, and it could vastly improve the sound at outdoor concerts. Instead of allowing the sound to disperse into the surrounding atmosphere, you could direct it at audience members hundreds of yards away from the stage. Music can travel from an emitter at ranges up to five hundred feet, with the intensity of the sound remaining virtually the same every step of the way.
Thinking of HyperSonic Sound as a laser beam also led Norris to imagine security applications. Law enforcement officials, for example, could use HSS for policing crowds. Instead of speaking through a megaphone to an entire group, an officer could direct a vocal warning—“Drop your weapon!”—to one person in a crowd, and only that person would hear it. “It allows for individual communications in public spaces,” Norris says. Ambulance sirens could be directed only at cars directly in the emergency route rather than throughout an entire neighborhood. “In’dat cool?” Norris asks.
The first companies to express interest in HSS and the Audio Spotlight represented a wide range of industries. Sony is selling directional sound systems for use in department stores and museums in Europe. Disney has evaluated it for its theme parks. The U.S. Army and Navy are using it to hail troops and warn enemies. Retailers have been testing it for in-store sale pitches, with products and displays talking to one customer at a time. Vending machine companies have expressed interest, and DaimlerChrysler is evaluating it for car audio. Both Norris and Pompei are contesting one another to win these industrial and military customers before going after the general consumer market. Replacing the millions of mechanical speakers that are sold annually remains the long-term goal. Before they reach mass acceptance, though, both inventors will have to overcome early performance kinks, such as an inability to produce low bass tones.
According to Norris and other inventors, the great news about analogizing is that it’s one of many thinking strategies that anyone can learn to do with practice. Analogizing is one of the higher-order cognitive tools that separates us from other animals. Once you see the pattern of how analogies work and how this strategy can generate many useful ideas, you may be able to practice it regularly.
When you’re moving from base to target, your analogies can stick closely to one domain. For example, a transistor works like a vacuum tube. But some of the most evocative analogies leap across domains: A flying machine might be like a bird. But that doesn’t mean an automobile should be like a horse. “When man wanted to make a machine that would walk,” goes a French proverb, “he created the wheel, which does not resemble a leg.” Those who invented and reinvented the wheel in isolated civilizations thousands of years ago probably saw something—a rock, an acorn, the moon, a person tumbling downhill—that triggered analogies. Like children, grownup inventors are constantly scanning the world, looking at objects and processes, and asking, “What does this remind me of?” Sometimes, analogies are so powerful that they do much of the work of invention for you. Often, what’s left is simply a matter of ironing out the wrinkles.