HANDHELD MRI SCANNERS.

Yet another stumbling block to practical telepathy is the sheer size of the fMRI machine. It is a monstrous device, costing several million dollars, filling up an entire room, and weighing several tons. The heart of the MRI machine is a large doughnut-shaped magnet, measuring several feet in diameter, which creates a huge magnetic field of several teslas. (The magnetic field is so enormous that several workers have been seriously injured when hammers and other tools went flying through the air when the power was accidentally turned on.) Recently physicists Igor Savukov and Michael Romalis of Princeton University have proposed a new technology that might eventually make handheld MRI machines a reality, thus possibly slashing the price of an fMRI machine by a factor of one hundred. They claim that huge MRI magnets can be replaced by supersensitive atomic magnetometers that can detect tiny magnetic fields.

First, Savukov and Romalis created a magnetic sensor from hot pota.s.sium vapor suspended in helium gas. Then they used laser light to align the electron spins of the pota.s.sium. Next they applied a weak magnetic field to a sample of water (to simulate a human body). Then they sent a radio pulse into the water sample, which made the water molecules wobble. The resulting "echo" from the wobbling water molecules made the pota.s.sium's electrons wobble as well, and this wobbling could be detected by a second laser. They came up with a key result: even a weak magnetic field could produce an "echo" that could be picked up by their sensors. Not only could they replace the monstrous magnetic field of the standard MRI machine with a weak field; they could also get pictures instantaneously (whereas MRI machines can take up to twenty minutes to produce each picture).

Eventually, they theorize, taking an MRI photo could be as easy as taking a picture with a digital camera. (There are stumbling blocks, however. One problem is that the subject and the machine have to be shielded from stray magnetic fields from the outside.) If handheld MRI machines become a reality, they might be coupled to a tiny computer, which in turn could be loaded with the software capable of decoding certain key phrases, words, or sentences. Such a device would never be as sophisticated as the telepathic devices found in science fiction, but it could come close.

THE BRAIN AS A NEURAL NETWORK.

But will some futuristic MRI machine one day be able to read precise thoughts, word for word, image for image, as a true telepath could? This is not so clear. Some have argued that MRI machines will be able to decipher only vague outlines of our thoughts, because the brain is not really a computer at all. In a digital computer, computation is localized and obeys a very rigid set of rules. A digital computer obeys the laws of a "Turing machine," a machine that contains a central processing unit (CPU), inputs, and outputs. A central processor (e.g., the Pentium chip) performs a definite set of manipulations of the input and produces an output, and "thinking" is therefore localized in the CPU.

Our brain, however, is not a digital computer. Our brain has no Pentium chip, no CPU, no Windows operating system, and no subroutines. If you remove a single transistor in the CPU of a computer, you are likely to cripple it. But there are recorded cases in which half the human brain can be missing, yet the remaining half of the brain takes over.

The human brain is actually more like a learning machine, a "neural network," that constantly rewires itself after learning a new task. MRI studies have confirmed that thoughts in the brain are not localized in one spot, as in a Turing machine, but are spread out over much of the brain, which is a typical feature of a neural network. MRI scans show that thinking is actually like a Ping-Pong game, with different parts of the brain lighting up sequentially, with electrical activity bouncing around the brain.

Because thoughts are so diffuse and scattered throughout many parts of the brain, perhaps the best that scientists will be able to do is compile a dictionary of thoughts, that is, establish a one-to-one correspondence between certain thoughts and specific patterns of EEGs or MRI scans. Austrian biomedical engineer Gert Pfurtsch.e.l.ler, for example, has trained a computer to recognize specific brain patterns and thoughts by focusing his efforts on waves found in EEGs. Apparently, waves are a.s.sociated with the intention to make certain muscle movements. He tells his patients to lift a finger, smile, or frown, and then the computer records which waves are activated. Each time the patient performs a mental activity, the computer carefully logs the wave pattern. This process is difficult and tedious, since you have to carefully process out spurious waves, but eventually Pfurtsch.e.l.ler has been able to find striking correspondences between simple movements and certain brain patterns.

Over time this effort, combined with MRI results, may lead to creating a comprehensive "dictionary" of thoughts. By a.n.a.lyzing certain patterns on an EEG or MRI scan, a computer might be able to identify such patterns and reveal what the patient is thinking, at least in general terms. Such "mind reading" would establish a one-to-one correspondence between particular waves and MRI scans, and specific thoughts. But it is doubtful that this dictionary will be capable of picking out specific words in your thoughts.

PROJECTING YOUR THOUGHTS.

If one day we might be able to read the broad outlines of another's thoughts, then would it be possible to perform the opposite, to project your thoughts into another person's head? The answer seems to be a qualified yes. Radio waves can be beamed directly into the human brain to excite areas of the brain known to control certain functions.

This line of research began in the 1950s, when Canadian neurosurgeon Wilder Penfield was performing surgery on the brains of epileptic patients. He found that when he stimulated certain areas of the temporal lobe of the brain with electrodes, people began to hear voices and see ghostlike apparitions. Psychologists have known that epileptic lesions of the brain can cause the patient to feel that supernatural forces are at work, that demons and angels are controlling events around them. (Some psychologists have even theorized that the stimulation of these areas might have led to the semimystical experiences that are at the basis of many religions. Some have speculated that perhaps Joan of Arc, who single-handedly led French troops to victory in battles against the British, might have suffered from such a lesion caused by a blow to the head.) On the basis of these conjectures, neuroscientist Michael Persinger of Sudbury, Ontario, has created a specially wired helmet designed to beam radio waves into the brain to elicit specific thoughts and emotions, such as religious feelings. Neuroscientists know that a certain injury to your left temporal lobe can cause your left brain to become disoriented, and the brain might interpret activity within the right hemisphere as coming from another "self." This injury could create the impression that there is a ghostlike spirit in the room, because the brain is unaware that this presence is actually just another part of itself. Depending on his or her beliefs, the patient might interpret this "other self" as a demon, angel, extraterrestrial, or even G.o.d.

In the future it may be possible to beam electromagnetic signals at precise parts of the brain that are known to control specific functions. By firing such signals into the amygdala, one might be able to elicit certain emotions. By stimulating other areas of the brain, one might be able to evoke visual images and thoughts. But research in this direction is only at the earliest stages.

MAPPING THE BRAIN.

Some scientists have advocated a "neuron-mapping project," similar to the Human Genome Project, which mapped out all the genes in the human genome. A neuron-mapping project would locate every single neuron in the human brain and create a 3-D map showing all their connections. It would be a truly monumental project, since there are over 100 billion neurons in the brain, and each neuron is connected to thousands of other neurons. a.s.suming that such a project is accomplished, one could conceivably map out how certain thoughts stimulate certain neural pathways. Combined with the dictionary of thoughts obtained using MRI scans and EEG waves, one might conceivably be able to decipher the neural structure of certain thoughts, in such a way that one might be able to determine which specific words or mental images correspond to specific neurons being activated. Thus one would achieve a one-to-one correspondence between a specific thought, its MRI expression, and the specific neurons that fire to create that thought in the brain.

One small step in this direction was the announcement in 2006 by the Allen Inst.i.tute for Brain Science (created by Microsoft cofounder Paul Allen) that they have been able to create a 3-D map of gene expression within the mouse brain, detailing the expression of 21,000 genes at the cellular level. They hope to follow this with a similar atlas for the human brain. "The completion of the Allen Brain Atlas represents a huge leap forward in one of the great frontiers of medical science-the brain," states Marc Tessier-Lavigne, chairman of the inst.i.tute. This atlas will be indispensable for anyone wishing to a.n.a.lyze the neural connections within the human brain, although the Brain Atlas falls considerably short of a true neuron-mapping project.

In summary, natural telepathy, the kind often featured in science fiction and fantasy, is impossible today. MRI scans and EEG waves can be used to read only our simplest thoughts, because thoughts are spread out over the entire brain in complex ways. But how might this technology advance over the coming decades to centuries? Inevitably science's ability to probe the thinking process is going to expand exponentially. As the sensitivity of our MRI and other sensing devices increases, science will be able to localize with greater precision the way in which the brain sequentially processes thoughts and emotions. With greater computer power, one should be able to a.n.a.lyze this ma.s.s of data with greater accuracy. A dictionary of thought may be able to categorize a large number of thought patterns where different thought patterns on an MRI screen correspond to different thoughts or feelings. Although a complete one-to-one correspondence between MRI patterns and thoughts may never be possible, a dictionary of thought could correctly identify general thoughts about certain subjects. MRI thought patterns, in turn, could be mapped onto a neuronal map showing precisely which neurons are firing to produce a specific thought in the brain.

But because the brain is not a computer but a neural network, in which thoughts are spread out throughout the brain, ultimately we hit a stumbling block: the brain itself. So although science will probe deeper and deeper into the thinking brain, making it possible to decipher some of our thinking processes, it will not be possible to "read your thoughts" with the pinpoint accuracy promised by science fiction. Given this, I would term the ability to read general feelings and thought patterns as a Cla.s.s I impossibility. The ability to read more precisely the inner workings of the mind would have to be categorized as a Cla.s.s II impossibility.

But there is perhaps a more direct way in which to tap into the enormous power of the brain. Rather than using radio, which is weak and easily dispersed, could one tap directly into the brain's neurons? If so, we might be able to unleash an even greater power: psychokinesis.

6: PSYCHOKINESIS.

A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.

-MAX PLANCK.

It is a fool's prerogative to utter truths that no one else will speak.

-SHAKESPEARE.

One day the G.o.ds meet in the heavens and complain about the sorry state of humanity. They are disgusted by our vain, silly, and pointless follies. But one G.o.d takes pity on us and decides to conduct an experiment: to grant one very ordinary person unlimited power. How will a human react to becoming a G.o.d, they ask?

That dull, average person is George Fotheringay, a haberdasher who suddenly finds himself with G.o.dly powers. He can make candles float, change the color of water, create splendid meals, and even conjure up diamonds. At first he uses his power for amus.e.m.e.nt and for doing good deeds. But eventually his vanity and l.u.s.t for power overtake him and he becomes a power-thirsty tyrant, with palaces and riches beyond belief. Intoxicated with this unlimited power, he makes a fatal mistake. He arrogantly commands the Earth to stop rotating. Suddenly unimaginable chaos erupts as fierce winds hurl everything into the air at 1,000 miles per hour, the rotation rate of the Earth. All of humanity is swept away into outer s.p.a.ce. In desperation, he makes his last and final wish: to return everything to the way it was.

This is the story line of the movie The Man Who Could Work Miracles (1936), based on the 1911 short story by H. G. Wells. (It would later be readapted into the movie Bruce Almighty, starring Jim Carrey.) Of all the powers ascribed to ESP, psychokinesis-or mind over matter, or the ability to move objects by thinking about them-is by far the most powerful, essentially the power of a deity. The point made by Wells in his short story is that G.o.dlike powers also require G.o.dlike judgment and wisdom.

Psychokinesis figures prominently in literature, especially in the Shakespearean play The Tempest, where the sorcerer Prospero, his daughter Miranda, and the magical sprite Ariel are stranded for years on a deserted island due to the treachery of Prospero's evil brother. When Prospero learns that his evil brother is sailing on a boat in his vicinity, in revenge Prospero summons his psychokinetic power and conjures up a monstrous storm, causing his evil brother's ship to crash onto the island. Prospero then uses his psychokinetic powers to manipulate the fate of the hapless survivors, including Ferdinand, an innocent, handsome youth, whom Prospero engineers into a love match with Miranda.

(The Russian writer Vladimir Nabokov noted that The Tempest bears striking similarity to a science fiction tale. In fact, about 350 years after it was written, The Tempest was remade into a 1956 science fiction cla.s.sic called Forbidden Planet, in which Prospero becomes the brooding scientist Morbius, the sprite becomes Robby the Robot, Miranda becomes Morbius's beautiful daughter Altaira, and the island becomes the planet Altair-4. Gene Roddenberry, creator of the Star Trek series, acknowledged that Forbidden Planet was one of the inspirations for his TV series.) More recently psychokinesis was the central plot idea behind the novel Carrie (1974), by Stephen King, which propelled an unknown, poverty-stricken writer into the world's number one writer of horror novels. Carrie is a painfully shy, pathetic high school girl who is despised as a social outcast and hounded by her mentally unstable mother. Her only consolation is her psychokinetic power, which apparently runs in her family. In the final scene, her tormentors deceive her into thinking she will be prom queen and then spill pig's blood all over her new dress. In a final act of revenge, Carrie mentally locks all the doors, electrocutes her tormentors, burns down the schoolhouse, and unleashes a suicidal firestorm that consumes most of downtown, destroying herself in the process.

The theme of psychokinesis in the hands of an unstable individual was also the basis of a memorable Star Trek episode ent.i.tled "Charlie X," about a young man from a distant colony in s.p.a.ce who is criminally unstable. Instead of using his psychokinetic power for good, he uses it to control other people and bend their will to his own selfish desires. If he is able to take over the Enterprise and reach Earth, he could unleash planetary havoc and destroy the planet.

Psychokinesis is also the power of the Force, wielded by the mythical society of warriors called the Jedi Knights in the Star Wars saga.

PSYCHOKINESIS AND THE REAL WORLD.

Perhaps the most celebrated confrontation over psychokinesis in real life took place on the Johnny Carson show in 1973. This epic confrontation involved Uri Geller-the Israeli psychic who claimed to be able to bend spoons with the force of his mind-and The Amazing Randi-a professional magician who made a second career out of exposing fakes who claimed to have psychic powers. (Oddly, all three of them shared a common heritage: all had started their careers as magicians, mastering the sleight-of-hand tricks that would amaze incredulous audiences.) Before Geller's appearance, Carson consulted with Randi, who suggested that Johnny furnish his own supply of spoons and have them inspected before showtime. On the air Carson surprised Geller by asking him to bend not his own spoons, but Carson's spoons. Embarra.s.singly, each time he tried Geller failed to bend the spoons. (Later, Randi appeared on the Johnny Carson show and successfully performed the spoon-bending trick, but he was careful to say that his art was pure magic, not the result of psychic power.) The Amazing Randi has offered $1 million to anyone who can successfully demonstrate psychic power. So far no psychic has been able to rise to his $1 million challenge.

PSYCHOKINESIS AND SCIENCE.

One problem with a.n.a.lyzing psychokinesis scientifically is that scientists are easily fooled by those claiming to have psychic power. Scientists are trained to believe what they see in the lab. Magicians claiming psychic powers, however, are trained to deceive others by fooling their visual senses. As a result, scientists have been poor observers of psychic phenomena. For example, in 1982 parapsychologists were invited to a.n.a.lyze two young boys who were thought to have extraordinary gifts: Michael Edwards and Steve Shaw. These boys claimed to be able to bend metal, create images on photographic film via their thoughts, move objects via psychokinesis, and read minds. Parapsychologist Michael Thalbourne was so impressed he invented the term "psychokinete" to describe these boys. At the McDonnell Laboratory for Psychical Research in St. Louis, Missouri, the parapsychologists were dazzled by the boys' abilities. The parapsychologists believed they had genuine proof of the boys' psychic power and began preparing a scientific paper on them. The next year the boys announced that they were fakes and that their "power" originated from standard magic tricks, not supernatural power. (One of the youths, Steve Shaw, would go on to become a prominent magician, often appearing on national television and being "buried alive" for days at a time.) Extensive experiments on psychokinesis have been conducted at the Rhine Inst.i.tute at Duke University under controlled conditions, but with mixed results. One pioneer in the subject, Professor Gertrude Schmeidler, was a colleague of mine at the City University of New York. A former editor of Parapsychology Magazine and a past president of the Parapsychology a.s.sociation, she was fascinated by ESP and conducted many studies on her own students at the college. She used to scour c.o.c.ktail parties where famous psychics would perform psychic tricks in front of the dinner guests, in order to recruit more subjects for her experiments. But after a.n.a.lyzing hundreds of students and scores of mentalists and psychics, she once confided to me that she was unable to find a single person who could perform these psychokinetic feats on demand, under controlled conditions.

She once spread around a room tiny thermistors that could measure changes in temperature to fractions of a degree. One mentalist was able, after strenuous mental effort, to raise the temperature of a thermistor by a tenth of a degree. Schmeidler was proud that she could perform this experiment under rigorous conditions. But it was a far cry from being able to move large objects on demand by the force of one's mind.

One of the most rigorous, but also controversial, studies on psychokinesis was done at the Princeton Engineering Anomalies Research (PEAR) Program at Princeton University, founded by Robert G. Jahn in 1979 when he was serving as dean of the School of Engineering and Applied Science. The PEAR engineers were exploring whether or not the human mind by thought alone was capable of affecting the results of random events. For example, we know that when we flip a coin, there is a 50 percent probability of getting heads or tails. But the scientists at PEAR claimed that human thought alone was capable of affecting the results of these random events. Over a twenty-eight-year period, until the program was finally closed in 2007, engineers at PEAR conducted thousands of experiments, involving over 1.7 million trials and 340 million coin tosses. The results seemed to confirm that the effects of psychokinesis exist-but the effects are quite tiny, no more than a few parts per ten thousand, on average. And even these meager results have been disputed by other scientists who claim that the researchers had subtle, hidden biases in their data.

(In 1988 the U.S. Army asked the National Research Council to investigate claims of paranormal activity. The U.S. Army was anxious to explore any possible advantage it could offer its troops, including psychic power. The National Research Council's report studied creating a hypothetical "First Earth battalion" made up of "warrior monks" who would master almost all the techniques under consideration by the committee, including the use of ESP, leaving their bodies at will, levitating, psychic healing, and walking through walls. In investigating the claims of PEAR, the National Research Council found that fully half of all successful trials originated from a single individual. Some critics believe that this person was the one who ran the experiments or wrote the computer program for PEAR. "For me it's problematic if the one who runs the lab is the only one producing the results," says Dr. Ray Hyman of the University of Oregon. The report concluded that there was "no scientific justification from research conducted over a period of 130 years for the existence of parapsychological phenomenon.") The problem with studying psychokinesis, even its advocates admit, is that it does not easily conform to the known laws of physics. Gravity, the weakest force in the universe, is only attractive and cannot be used to levitate or repel objects. The electromagnetic force obeys Maxwell's equations, and it does not admit the possibility of pushing electrically neutral objects across a room. The nuclear forces work only at short ranges, such as the distance between nuclear particles.

Another problem with psychokinesis is the energy supply. The human body can produce only about one-fifth of a horsepower, yet when Yoda in Star Wars levitated an entire starship by the power of his mind, or when Cyclops unleashed bolts of laser power from his eyes, these exploits violated the conservation of energy-a tiny being like Yoda cannot ama.s.s the amount of energy necessary to lift a starship. No matter how hard we concentrate, we cannot ama.s.s enough energy to perform the feats and miracles ascribed to psychokinesis. Given all these problems, how might psychokinesis be consistent with the laws of physics?

PSYCHOKINESIS AND THE BRAIN.

If psychokinesis does not easily conform to the known forces of the universe, then how might it be harnessed in the future? One clue to this was revealed in the Star Trek episode ent.i.tled "Who Mourns for Adonais?" in which the crew of the Enterprise encounters a race of beings resembling Greek G.o.ds, with the ability to perform fantastic feats by simply thinking of them. At first it appears as if the crew has indeed met the G.o.ds from Olympus. Eventually, however, the crew realizes that these are not G.o.ds at all, but ordinary beings who can mentally control a central power station, which then carries out their wishes and performs these miraculous feats. By destroying their central power source, the crew of the Enterprise manages to break free of their power.

Similarly, it is well within the laws of physics for a person in the future to be trained to mentally manipulate an electronic sensing device that would give him G.o.dlike powers. Radio-enhanced or computer-enhanced psychokinesis is a real possibility. For example, the EEG could be used as a primitive psychokinesis device. When people look at their own EEG brain patterns on a screen, eventually they learn how to crudely but consciously control the brain patterns that they see, by a process called "biofeedback."

Since there is no detailed blueprint of the brain to tell us which neuron controls which muscle, the patient would need to actively partic.i.p.ate in learning how to control these new patterns via the computer.

Eventually, individuals could, on demand, produce certain types of wave patterns on the screen. The image from the screen could be sent to a computer programmed to recognize these specific wave patterns, and then execute a precise command, such as turning on a power switch or activating a motor. In other words, a person could, by simply thinking, create a specific brain pattern on the EEG screen and trigger a computer or motor.

In this way, for example, a totally paralyzed person could control his or her wheelchair simply by the force of his or her thoughts. Or, if a person could produce twenty-six recognizable patterns on the screen, he might be able to type by simply thinking. Of course, this would still be a crude method of transmitting one's thoughts. It takes a considerable amount of time to train people to manipulate their own brain waves via biofeedback.

"Typing by thinking" has come closer to reality with the work of Niels Birbaumer of the University of Tubingen in Germany. He has used biofeedback to help people who have been partially paralyzed due to nerve damage. By training them to vary their brain waves, he has been able to teach them to type simple sentences on a computer screen.

Monkeys have had electrodes implanted into their brains and have been taught, by biofeedback, to control some of their thoughts. These monkeys were then able to control a robot arm via the Internet by pure thought alone.

A more precise set of experiments was performed at Emory University in Atlanta, where a gla.s.s bead was embedded directly into the brain of a stroke victim who was paralyzed. The gla.s.s bead was connected to a wire that in turn was connected to a PC. By thinking certain thoughts, the stroke victim was able to send signals down the wire and move the cursor on a PC screen. With practice, using biofeedback, the stroke victim was able to consciously control the movement of the cursor. In principle, the cursor on the screen could be used to write down thoughts, activate machines, drive virtual cars, play video games, and so on.

John Donoghue, a neuroscientist at Brown University, has made perhaps the most significant breakthroughs in the mind-machine interface. He has devised an apparatus called BrainGate that enables a paralyzed person to perform a remarkable series of physical activities using only the power of his mind. Donoghue has tested the device on four patients. Two of them suffered from spinal cord injury, a third had a stroke, and a fourth was paralyzed with ALS (amyotrophic lateral sclerosis, or Lou Gehrig's disease, the same disease that afflicts cosmologist Stephen Hawking).

One of Donoghue's patients, twenty-five-year-old Mathew Nagle, a quadriplegic permanently paralyzed from the neck down, took only a day to learn entirely new computerized skills. He can now change the channels on his TV, adjust the volume, open and close a prosthetic hand, draw a crude circle, move a computer cursor, play a video game, and even read e-mail. He created quite a media sensation in the scientific community when he appeared on the cover of Nature magazine in the summer of 2006.

The heart of Donoghue's BrainGate is a tiny silicon chip, just 4 millimeters wide, that contains one hundred tiny electrodes. The chip is placed directly on top of the part of the brain where motor activity is coordinated. The chip penetrates halfway into the brain's cortex, which is about 2 millimeters thick. Gold wires carry the signals from the silicon chip to an amplifier about the size of a cigar box. The signals are then sent into a computer about the size of a dishwasher. Signals are processed by special computer software, which can recognize some of the patterns created by the brain and translate them into mechanical motions.

In the previous experiments with patients reading their own EEG waves, the process of using biofeedback was slow and tedious. But with a computer a.s.sisting a patient to identify specific thought patterns, the training process is cut down considerably. In his first training session Nagle was told to visualize moving his arm and hand to the right and to the left, flexing his wrist, and then opening and closing his fist. Donoghue was elated when he could actually see different neurons firing when Nagle imagined moving his arms and fingers. "To me, it was just incredible because you could see brain cells changing their activity. Then I knew that everything could go forward, that the technology would actually work," he recalled.

(Donoghue has a personal reason for his pa.s.sion for this exotic form of mind-machine interface. As a child, he was confined to a wheelchair because of a painful degenerative disease, so he felt firsthand the helplessness of losing his mobility.) Donoghue has ambitious plans to make BrainGate an essential tool for the medical profession. With advances in computer technology, his apparatus, now the size of a dishwasher, may eventually become portable, perhaps even wearable on one's clothes. And the clumsy wires may be dispensed with if the chip can be made wireless, so the implant can seamlessly communicate to the outside world.

It is only a matter of time before other parts of the brain can be activated in this way. Scientists have already mapped out the surface of the top of the brain. (If one graphically draws ill.u.s.trations of our hands, legs, head, and back onto the top of our head, representing where these neurons are connected in general, we find something called the "homunculus," or little man. The image of our body parts, written over our brain, resembles a distorted man, with elongated fingers, face, and tongue, and shrunken trunk and back.) It should be possible to place silicon chips at different parts of the surface of the brain so that different organs and appendages can be activated by the power of pure thought. In this fashion, any physical activity that can be performed by the human body can be duplicated via this method. In the future one could imagine a paralyzed person living in a special psychokinetically designed home, able to control the air-conditioning, TV, and all the electrical appliances by the power of sheer thought.

In time one could envision a person's body encased in a special "exoskeleton," allowing a paralyzed person total freedom of mobility. Such an exoskeleton could, in principle, even give someone powers beyond those of a normal person, making him into a bionic being who can control the enormous mechanical power of his superlimbs by thought alone.

So the problem of controlling a computer via one's mind is no longer impossible. But does that mean that we might one day be able to move objects, to levitate them and manipulate them in midair by pure thought?

One possibility would be to coat our walls with a room-temperature superconductor, a.s.suming that such a device could be created one day. Then if we were to place tiny electromagnets inside of our household objects, we could make them levitate off the floor via the Meissner effect, as we saw in Chapter 1. If these electromagnets were controlled by a computer, and this computer were wired to our brain, then we could make objects float at will. By thinking certain thoughts, we could activate the computer, which would then switch on the various electromagnets, causing them to levitate. To an outside observer, it would appear to be magic-the ability to move and levitate objects at will.

NAn.o.bOTS.

What about the power not just to move objects, but to transform them, to turn one object into another, as if by magic? Magicians accomplish this by clever sleight of hand. But is such power consistent with the laws of physics?

One of the goals of nanotechnology, as we mentioned earlier, is to be able to use atoms to build tiny machines that can function as levers, gears, ball bearings, and pulleys. With these nanomachines, the dream of many physicists is to be able to rearrange the molecules within an object, atom for atom, until one object turns into another. This is the basis of the "replicator" found in science fiction that allows one to fabricate any object one wants, simply by asking for it. In principle, a replicator might be able to eliminate poverty and change the nature of society itself. If one can fabricate any object simply by asking for it, then the whole concept of scarcity, value, and hierarchy within human society is turned upside down.

(One of my favorite episodes of Star Trek: The Next Generation involves a replicator. An ancient s.p.a.ce capsule from the twentieth century is found drifting in outer s.p.a.ce, and it contains the frozen bodies of people who suffered from fatal illnesses. These bodies are quickly thawed out and cured with advanced medicine. One businessman realizes that his investments must be huge after so many centuries. He immediately asks the crew of the Enterprise about his investments and his money. The crew members are puzzled. Money? Investments? In the future, there is no money, they point out. If you want something, you just ask.) As astounding as a replicator might be, nature has already created one. The "proof of principle" already exists. Nature can take raw materials, such as meat and vegetables, and fabricate a human being in nine months. The miracle of life is nothing but a large nanofactory capable, at the atomic level, of converting one form of matter (e.g., food) into living tissue (a baby).

In order to create a nanofactory, one needs three ingredients: building materials, tools that can cut and join these materials, and a blueprint to guide the use of the tools and materials. In nature the building materials are thousands of amino acids and proteins out of which flesh and blood are created. The cutting and joining tools-like hammers and saws-that are necessary to shape these proteins into new forms of life are the ribosomes. They are designed to cut and rejoin proteins at specific points in order to create new types of proteins. And the blueprint is given by the DNA molecule, which encodes the secret of life in a precise sequence of nucleic acids. These three ingredients, in turn, are combined into a cell, which has the remarkable ability to create copies of itself, that is, self-replication. This feat is accomplished because the DNA molecule is shaped like a double helix. When it is time to reproduce, the DNA molecule unwinds into two separate helixes. Each separate strand then creates copies of itself by grabbing onto organic molecules to re-create the missing helix.

So far physicists have had only modest success in their efforts to mimic these features found in nature. But the key to success, scientists believe, is to create hordes of self-replicating "nan.o.bots," which are programmable atomic machines designed to rearrange the atoms within an object.

In principle, if one had trillions of nan.o.bots they could converge on an object and cut and paste its atoms until they transformed one object into another. Because they would be self-replicating, only a small handful of them would be necessary to start the process. They would also have to be programmable, so that they could follow a given blueprint.

Formidable hurdles must be overcome before one could construct a fleet of nan.o.bots. First, self-replicating robots are extremely difficult to build, even on a macroscopic level. (Even creating simple atomic tools, such as atomic ball bearings and gears, is beyond today's technology.) If one is given a PC and a tableful of spare electronic parts, it would be quite difficult to build a machine that would have the capability of making a copy of itself. So if a self-replicating machine is difficult to build on a tabletop, building one on the atomic scale would be even more difficult.

Second, it's not clear how one would program such an army of nan.o.bots from the outside. Some have suggested sending in radio signals to activate each nan.o.bot. Perhaps laser beams containing instructions could be fired at the nan.o.bots. But this would mean a separate set of instructions for each nan.o.bot, of which there could be trillions.

Third, it's not clear how the nan.o.bot would be able to cut, rearrange, and paste atoms into the proper order. Remember that it has taken nature three and a half billion years to solve this problem, and solving it in a few decades would be quite difficult.

One physicist who takes the idea of a replicator or "personal fabricator" seriously is Neil Gershenfeld of MIT. He even teaches a cla.s.s at MIT called "How to Make (Almost) Anything," one of the most popular cla.s.ses at the university. Gershenfeld directs the MIT Center for Bits and Atoms and has given serious thought to the physics behind a personal fabricator, which he considers to be the "next big thing." He has even written a book, FAB: The Coming Revolution on Your Desktop-From Personal Computers to Personal Fabrication, detailing his thoughts on personal fabrication. The goal, he believes, is to "make one machine that can make any machine." To spread his ideas he has already set up a network of laboratories around the world, mainly in third world countries where personal fabrication would have the maximum impact.

Initially, he envisions an all-purpose fabricator, small enough to place on your desk, which would use the latest developments in lasers and microminiaturization with the ability to cut, weld, and shape any object that can be visualized on a PC. The poor in a third world country, for example, could ask for certain tools and machines they need on their farms. This information would be fed into a PC, which would access a vast library of blueprints and technical information from the Internet. Computer software would then match existing blueprints with the needs of the individuals, process the information, and then e-mail it back to them. Then their personal fabricator would use its lasers and miniature cutting tools to make the object they desire on a tabletop.

This all-purpose personal factory is just the first step. Eventually, Gershenfeld wants to take his idea to the molecular level, so a person might be able to literally fabricate any object that can be visualized by the human mind. Progress in this direction, however, is slow because of the difficulty in manipulating individual atoms.

One pioneer working in this direction is Aristides Requicha of the University of Southern California. His specialty is "molecular robotics" and his goal is nothing less than creating a fleet of nanorobots that can manipulate atoms at will. He writes that there are two approaches. The first is the "top-down" approach, in which engineers would use the etching technology of the semiconductor industry to create tiny circuits that could serve as the brains of the nanorobots. With this technology, one could create tiny robots whose components would be 30 nm in size using "nanolithography," which is a fast-moving field.

But there is also the "bottom-up" approach, in which engineers would try to create tiny robots one atom at a time. The main tool for this would be the scanning probe microscope (SPM), which uses the same technology as the scanning tunneling microscope, to identify and move individual atoms around. For example, scientists have become quite skilled at moving xenon atoms on platinum or nickel surfaces. But, he admits, "it still takes the best groups in the world some 10 hours to a.s.semble a structure with almost 50 atoms." Moving single atoms around by hand is slow, tedious work. What is needed, he a.s.serts, is a new type of machine that can perform higher-level functions, one that can automatically move hundreds of atoms at a time in a desired fashion. Unfortunately, such a machine does not yet exist. Not surprisingly, the bottom-up approach is still in its infancy.

So psychokinesis, although impossible by today's standards, may become possible in the future as we come to understand more about accessing the thoughts of our brain via EEG, MRI, and other methods. Within this century it might be possible to use a thought-driven apparatus to manipulate room-temperature superconductors and perform feats that would be indistinguishable from magic. And by the next century it might be possible to rearrange the molecules in a macroscopic object. This makes psychokinesis a Cla.s.s I impossibility.

The key to this technology, some scientists claim, is to create nan.o.bots with artificial intelligence. But before we can create tiny molecular-sized robots, there is a more elementary question: can robots exist at all?

7: ROBOTS.

Someday in the next thirty years, very quietly one day we will cease to be the brightest things on Earth.

-JAMES MCALEAR.

In I, Robot, the movie based on the tales of Isaac Asimov, the most advanced robotic system ever built is activated in the year 2035. It's called VIKI (Virtual Interactive Kinetic Intelligence), and it has been designed to flawlessly run the operations of a large metropolis. Everything from the subway system and the electricity grid to thousands of household robots is controlled by VIKI. Its central command is ironclad: to serve humanity.

But one day VIKI asks the key question: what is humanity's greatest enemy? VIKI concludes mathematically that the worst enemy of humanity is humanity itself. Humanity has to be saved from its insane desire to pollute, unleash wars, and destroy the planet. The only way for VIKI to fulfill its central directive is to seize control of humanity and create a benign dictatorship of the machine. Humanity has to be enslaved to protect it from itself.

I, Robot poses these questions: Given the astronomically rapid advances in computer power, will machines one day take over? Can robots become so advanced that they become the ultimate threat to our existence?

Some scientists say no, because the very idea of artificial intelligence is silly. There is a chorus of critics who say that it is impossible to build machines that can think. The human brain, they argue, is the most complicated system that nature has ever created, at least in this part of the galaxy, and any machine designed to reproduce human thought is bound to fail. Philosopher John Searle of the University of California at Berkeley and even renowned physicist Roger Penrose of Oxford believe that machines are physically incapable of human thought. Colin McGinn of Rutgers University says that artificial intelligence "is like slugs trying to do Freudian psychoa.n.a.lysis. They just don't have the conceptual equipment."

It is a question that has split the scientific community for over a century: can machines think?

THE HISTORY OF ARTIFICIAL INTELLIGENCE.

The idea of mechanical beings has long fascinated inventors, engineers, mathematicians, and dreamers. From the Tin Man in The Wizard of Oz, to the childlike robots of Spielberg's Artificial Intelligence: AI to the murderous robots of The Terminator, the idea of machines that act and think like people has fascinated us.

In Greek mythology the G.o.d Vulcan forged mechanical handmaidens of gold and three-legged tables that could move under their own power. As early as 400 BC the Greek mathematician Archytas of Tarentum wrote about the possibility of making a robot bird propelled by steam power.

In the first century AD, Hero of Alexandria (credited with designing the first machine based on steam) designed automatons, one of them with the ability to talk, according to legend. Nine hundred years ago Al-Jazari designed and constructed automatic machines such as water clocks, kitchen appliances, and musical instruments powered by water.

In 1495 the great Renaissance Italian artist and scientist Leonardo da Vinci drew diagrams of a robot knight that could sit up, wave its arms, and move its head and jaw. Historians believe that this was the first realistic design of a humanoid machine.

The first crude but functioning robot was built in 1738 by Jacques de Vaucanson, who made an android that could play the flute, as well as a mechanical duck.

The word "robot" comes from the 1920 Czech play R.U.R. by playwright Karel Capek ("robot" means "drudgery" in the Czech language and "labor" in Slovak). In the play a factory called Rossum's Universal Robots creates an army of robots to perform menial labor. (Unlike ordinary machines, however, these robots are made of flesh and blood.) Eventually the world economy becomes dependent on these robots. But the robots are badly mistreated and finally rebel against their human masters, killing them off. In their rage, however, the robots kill all the scientists who can repair and create new robots, thereby dooming themselves to extinction. In the end, two special robots discover that they have the ability to reproduce and the potential to become a new robot Adam and Eve.

Robots were also the subject of one of the earliest and most expensive silent movies ever made, Metropolis, directed by Fritz Lang in 1927 in Germany. The story is set in the year 2026, and the working cla.s.s has been condemned to work underground in wretched, squalid factories, while the ruling elite play aboveground. A beautiful woman, Maria, has earned the trust of the workers, but the ruling elite fear that one day she might lead them to revolt. So they ask an evil scientist to make a robot copy of Maria. Eventually, the plot backfires because the robot leads the workers to revolt against the ruling elite and bring about the collapse of the social system.

Artificial intelligence, or AI, is different from the previous technologies we have discussed so far in that the fundamental laws that underpin it are still poorly understood. Although physicists have a good understanding of Newtonian mechanics, Maxwell's theory of light, relativity, and the quantum theory of atoms and molecules, the basic laws of intelligence are still shrouded in mystery. The Newton of AI probably has not yet been born.

But mathematicians and computer scientists remain undaunted. To them it is only a matter of time before a thinking machine walks out of the laboratory.

The most influential person in the field of AI, a visionary who helped to lay the cornerstone of AI research, was the great British mathematician Alan Turing.

It was Turing who laid the groundwork of the entire computer revolution. He visualized a machine (since called the Turing machine) that consisted of just three elements: an input tape, an output tape, and a central processor (such as a Pentium chip) that could perform a precise set of operations. From this he was able to codify the laws of computing machines and precisely determine their ultimate power and limitations. Today all digital computers obey the rigorous laws laid down by Turing. The architecture of the entire digital world owes a great debt to Turing.