Part 3 (1/2)
Another technological advance we might see by midcentury is true 3-D TV and movies. Back in the 1950s, 3-D movies required that you put on clunky gla.s.ses whose lenses were colored blue and red. This took advantage of the fact that the left eye and the right eye are slightly misaligned; the movie screen displayed two images, one blue and one red. Since these gla.s.ses acted as filters that gave two distinct images to the left and right eye, this gave the illusion of seeing three dimensions when the brain merged the two images. Depth perception, therefore, was a trick. (The farther apart your eyes are, the greater the depth perception. That is why some animals have eyes outside their heads: to give them maximum depth perception.) One improvement is to have 3-D gla.s.ses made of polarized gla.s.s, so that the left eye and right eye are shown two different polarized images. In this way, one can see 3-D images in full color, not just in blue and red. Since light is a wave, it can vibrate up and down, or left and right. A polarized lens is a piece of gla.s.s that allows only one direction of light to pa.s.s through. Therefore, if you have two polarized lenses in your gla.s.ses, with different directions of polarization, you can create a 3-D effect. A more sophisticated version of 3-D may be to have two different images flashed into our contact lens.
3-D TVs that require wearing special gla.s.ses have already hit the market. But soon, 3-D TVs will no longer require them, instead using lenticular lenses. The TV screen is specially made so that it projects two separate images at slightly different angles, one for each eye. Hence your eyes see separate images, giving the illusion of 3-D. However, your head must be positioned correctly; there are ”sweet spots” where your eyes must lie as you gaze at the screen. (This takes advantage of a well-known optical illusion. In novelty stores, we see pictures that magically transform as we walk past them. This is done by taking two pictures, shredding each one into many thin strips, and then interspersing the strips, creating a composite image. Then a lenticular gla.s.s sheet with many vertical grooves is placed on top of the composite, each groove sitting precisely on top of two strips. The groove is specially shaped so that, as you gaze upon it from one angle, you can see one strip, but the other strip appears from another angle. Hence, by walking past the gla.s.s sheet, we see each picture suddenly transform from one into the other, and back again. 3-D TVs will replace these still pictures with moving images to attain the same effect without the use of gla.s.ses.) But the most advanced version of 3-D will be holograms. Without using any gla.s.ses, you would see the precise wave front of a 3-D image, as if it were sitting directly in front of you. Holograms have been around for decades (they appear in novelty shops, on credit cards, and at exhibitions), and they regularly are featured in science fiction movies. In Star Wars, Star Wars, the plot was set in motion by a 3-D holographic distress message sent from Princess Leia to members of the Rebel Alliance. the plot was set in motion by a 3-D holographic distress message sent from Princess Leia to members of the Rebel Alliance.
The problem is that holograms are very hard to create.
Holograms are made by taking a single laser beam and splitting it in two. One beam falls on the object you want to photograph, which then bounces off and falls onto a special screen. The second laser beam falls directly onto the screen. The mixing of the two beams creates a complex interference pattern containing the ”frozen” 3-D image of the original object, which is then captured on a special film on the screen. Then, by flas.h.i.+ng another laser beam through the screen, the image of the original object comes to life in full 3-D.
There are two problems with holographic TV. First, the image has to be flashed onto a screen. Sitting in front of the screen, you see the exact 3-D image of the original object. But you cannot reach out and touch the object. The 3-D image you see in front of you is an illusion.
This means that if you are watching a 3-D football game on your holographic TV, no matter how you move, the image in front of you changes as if it were real. It might appear that you are sitting right at the 50-yard line, watching the game just inches from the football players. However, if you were to reach out to grab the ball, you would b.u.mp into the screen.
The real technical problem that has prevented the development of holographic TV is that of information storage. A true 3-D image contains a vast amount of information, many times the information stored inside a single 2-D image. Computers regularly process 2-D images, since the image is broken down into tiny dots, called pixels, and each pixel is illuminated by a tiny transistor. But to make a 3-D image move, you need to flash thirty images per second. A quick calculation shows that the information needed to generate moving 3-D holographic images far exceeds the capability of today's Internet.
By midcentury, this problem may be resolved as the bandwidth of the Internet expands exponentially.
What might true 3-D TV look like?
One possibility is a screen shaped like a cylinder or dome that you sit inside. When the holographic image is flashed onto the screen, we see the 3-D images surrounding us, as if they were really there.
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MIND OVER MATTER.
By the end of this century, we will control computers directly with our minds. Like Greek G.o.ds, we will think of certain commands and our wishes will be obeyed. The foundation for this technology has already been laid. But it may take decades of hard work to perfect it. This revolution is in two parts: First, the mind must be able to control objects around it. Second, a computer has to decipher a person's wishes in order to carry them out.
The first significant breakthrough was made in 1998, when scientists at Emory University and the University of Tubingen, Germany, put a tiny gla.s.s electrode directly into the brain of a fifty-six-year-old man who was paralyzed after a stroke. The electrode was connected to a computer that a.n.a.lyzed the signals from his brain. The stroke victim was able to see an image of the cursor on the computer screen. Then, by biofeedback, he was able to control the cursor of the computer display by thinking alone. For the first time, a direct contact was made between the human brain and a computer.
The most sophisticated version of this technology has been developed at Brown University by neuroscientist John Donoghue, who has created a device called BrainGate to help people who have suffered debilitating brain injuries communicate. He created a media sensation and even made the cover of Nature Nature magazine in 2006. magazine in 2006.
Donoghue told me that his dream is to have BrainGate revolutionize the way we treat brain injuries by harnessing the full power of the information revolution. It has already had a tremendous impact on the lives of his patients, and he has high hopes of furthering this technology. He has a personal interest in this research because, as a child, he was confined to a wheelchair due to a degenerative disease and hence knows the feeling of helplessness.
His patients include stroke victims who are completely paralyzed and unable to communicate with their loved ones, but whose brains are active. He has placed a chip, just 4 millimeters wide, on top of a stroke victim's brain, in the area that controls motor movements. This chip is then connected to a computer that a.n.a.lyzes and processes the brain signals and eventually sends the message to a laptop.
At first the patient has no control over the location of the cursor, but can see where the cursor is moving. By trial and error, the patient learns to control the cursor, and, after several hours, can position the cursor anywhere on the screen. With practice, the stroke victim is able to read and write e-mails and play video games. In principle a paralyzed person should be able to perform any function that can be controlled by the computer.
Initially, Donoghue started with four patients, two who had spinal cord injuries, one who'd had a stroke, and a fourth who had ALS (amyotrophic lateral sclerosis). One of them, a quadriplegic paralyzed from the neck down, took only a day to master the movement of the cursor with his mind. Today, he can control a TV, move a computer cursor, play a video game, and read e-mail. Patients can also control their mobility by manipulating a motorized wheelchair.
In the short term, this is nothing less than miraculous for people who are totally paralyzed. One day, they are trapped, helpless, in their bodies; the next day, they are surfing the Web and carrying on conversations with people around the world.
(I once attended a gala reception at Lincoln Center in New York in honor of the great cosmologist Stephen Hawking. It was heartbreaking to see him strapped into a wheelchair, unable to move anything but a few facial muscles and his eyelids, with nurses holding up his limp head and pus.h.i.+ng him around. It takes him hours and days of excruciating effort to communicate simple ideas via his voice synthesizer. I wondered if it was not too late for him to take advantage of the technology of BrainGate. Then John Donoghue, who was also in the audience, came up to greet me. So perhaps BrainGate is Hawking's best option.) Another group of scientists at Duke University have achieved similar results in monkeys. Miguel A. L. Nicolelis and his group have placed a chip on the brain of a monkey. The chip is connected to a mechanical arm. At first, the monkey flails about, not understanding how to operate the mechanical arm. But with some practice, these monkeys, using the power of their brains, are able to slowly control the motions of the mechanical arm-for example, moving it so that it grabs a banana. They can instinctively move these arms without thinking, as if the mechanical arm is their own. ”There's some physiological evidence that during the experiment they feel more connected to the robots than to their own bodies,” says Nicolelis.
This also means that we will one day be able to control machines using pure thought. People who are paralyzed may be able to control mechanical arms and legs in this way. For example, one might be able to connect a person's brain directly to mechanical arms and legs, bypa.s.sing the spinal cord, so the patient can walk again. Also, this may lay the foundation for controlling our world via the power of the mind.
MIND READING.
If the brain can control a computer or mechanical arm, can a computer read the thoughts of a person, without placing electrodes inside the brain?
It's been known since 1875 that the brain is based on electricity moving through its neurons, which generates faint electrical signals that can be measured by placing electrodes around a person's head. By a.n.a.lyzing the electrical impulses picked up by these electrodes, one can record the brain waves. This is called an EEG (electroencephalogram), which can record gross changes in the brain, such as when it is sleeping, and also moods, such as agitation, anger, etc. The output of the EEG can be displayed on a computer screen, which the subject can watch. After a while, the person is able to move the cursor by thinking alone. Already, Niels Birbaumer of the University of Tubingen has been able to train partially paralyzed people to type simple sentences via this method.
Even toy makers are taking advantage of this. A number of toy companies, including NeuroSky, market a headband with an EEG-type electrode inside. If you concentrate in a certain way, you can activate the EEG in the headband, which then controls the toy. For example, you can raise a Ping-Pong ball inside a cylinder by sheer thought.
The advantage of the EEG is that it can rapidly detect various frequencies emitted by the brain without elaborate, expensive equipment. But one large disadvantage is that the EEG cannot localize thoughts to specific locations of the brain.
A much more sensitive method is the fMRI (functional magnetic resonance imaging) scan. EEG and fMRI scans differ in important ways. The EEG scan is a pa.s.sive device that simply picks up electrical signals from the brain, so we cannot determine very well the location of the source. An fMRI machine uses ”echoes” created by radio waves to peer inside living tissue. This allows us to pinpoint the location of the various signals, giving us spectacular 3-D images of inside the brain.
The fMRI machine is quite expensive and requires a laboratory full of heavy equipment, but already it has given us breathtaking details of how the thinking brain functions. The fMRI scan allows scientists to locate the presence of oxygen contained within hemoglobin in the blood. Since oxygenated hemoglobin contains the energy that fuels cell activity, detecting the flow of this oxygen allows one to trace the flow of thoughts in the brain.
Joshua Freedman, a psychiatrist at the University of California, Los Angeles, says: ”It's like being an astronomer in the sixteenth century after the invention of the telescope. For millennia, very smart people tried to make sense of what was going on up in the heavens, but they could only speculate about what lay beyond unaided human vision. Then, suddenly, a new technology let them see directly what was there.”
In fact, fMRI scans can even detect the motion of thoughts in the living brain to a resolution of .1 millimeter, or smaller than the head of a pin, which corresponds to perhaps a few thousand neurons. An fMRI can thus give three-dimensional pictures of the energy flow inside the thinking brain to astonis.h.i.+ng accuracy. Eventually, fMRI machines may be built that can probe to the level of single neurons, in which case one might be able to pick out the neural patterns corresponding to specific thoughts.
A breakthrough was made recently by Kendrick Kay and his colleagues at the University of California at Berkeley. They did an fMRI scan of people as they looked at pictures of a variety of objects, such as food, animals, people, and common things of various colors. Kay and colleagues created a software program that could a.s.sociate these objects with the corresponding fMRI patterns. The more objects these subjects saw, the better the computer program was at identifying these objects on their fMRI scans.
Then they showed the same subjects entirely new objects, and the software program was often able to correctly match the object with the fMRI scan. When shown 120 pictures of new objects, the software program correctly identified the fMRI scan with these objects 90 percent of the time. When the subjects were shown 1,000 new pictures, the software program's success rate was 80 percent.
Kay says it is ”possible to identify, from a large set of completely novel natural images, which specific image was seen by an observer.... It may soon be possible to reconstruct a picture of a person's visual experience from measurements of brain activity alone.”
The goal of this approach is to create a ”dictionary of thought,” so that each object has a one-to-one correspondence to a certain fMRI image. By reading the fMRI pattern, one can then decipher what object the person is thinking about. Eventually, a computer will scan perhaps thousands of fMRI patterns that come pouring out of a thinking brain and decipher each one. In this way, one may be able to decode a person's stream of consciousness.
PHOTOGRAPHING A DREAM.
The problem with this technique, however, is that while it might be able to tell if you are thinking of a dog, for example, it cannot reproduce the actual image of the dog itself. One new line of research is to try to reconstruct the precise image that the brain is thinking of, so that one might be able to create a video of a person's thoughts. In this way, one might be able to make a video recording of a dream.
Since time immemorial, people have been fascinated by dreams, those ephemeral images that are sometimes so frustrating to recall or understand. Hollywood has long envisioned machines that might one day send dreamlike thoughts into the brain or even record them, as in movies like Total Recall. Total Recall. All this, however, was sheer speculation. All this, however, was sheer speculation.