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THE SCIENCE OF BEING UNSEEN
Have you ever seen a photograph of DNA? Most likely not. The biological blueprint molecule is so small that no optical lens can possibly provide enough magnification for our eyes to see it. In the future, however, metamaterials might change that. Generally speaking, metamaterials are composite structures that interact with waves in ways that are dependent on their structure. For example imagine a sheet of fiberglass circuit board imprinted with an array of tiny copper rings. The rings are at most a few millimeters in diameter. Such an array would bend electromagnetic waves that go through it with a certain wavelength. The wavelength is dependent on the size of the rings. Smaller rings affect radiation with smaller wavelengths (higher frequencies). When such a structure is arranged in concentric circles, it can be used to bend light around the center. As light passes through the layers of the metamaterial it is redirected around the center like a river around a boulder. An observer outside the metamaterial would not see the space in its center or any object placed there. For certain wavelengths of light an object would be invisible. At first this “cloaking” technology only worked for microwaves, but, since then, considerable effort has been devoted to developing metamaterials that work at smaller wavelengths. To have an invisibility effect in the visible light range would require much smaller structures, such as the copper rings, to the point where nanoscale fabrication techniques are required. Nanotechnology is neither cheap nor easy, but it is within our means. Barring the cliché mention of certain wizards, there is a definite possibility that someday we may be able to hide objects from plain sight, thanks to mind-boggling technology.
What does that have to do with DNA? Well, metamaterials can be designed to manipulate light in many ways. Conventional lenses have fundamental limits to their magnification capabilities. Metamaterials effectively break conventional rules and extend the limits of optical magnification to the point where molecules can be observed. A microscope equipped with a “superlens” would allow you to view DNA molecules and other similarly sized objects.
Metamaterials can also greatly improve the functionality of radio antennas, making them smaller and more efficient. With sufficient ability to manipulate light, metamaterial structures could one day replace the circuit boards we know so well. Replacing electric signals with light pulses, computers would work faster and produce less heat. There are claims that metamaterials could even function as artificial noses for computers to sniff out bombs.
As I said earlier, generally, metamaterials manipulate waves. Meaning, this field of technology is not limited to electromagnetic radiation; it can also apply to vibrations in matter. Think of the invisibility idea applied to sound; you could have a perfectly soundproof room. Sound waves can be redirected like light waves. How about water waves? Perhaps a very large metamaterial structure could “cloak” coastal areas from rough sea storms. Or ground waves? In the future, maybe buildings will be able to safely redirect seismic vibrations around them. It would seem the only limitations on metamaterials are our imaginations and our small-scale engineering abilities.
A FOUNDATION OF BUCKYTUBES
Carbon has a wide range of macroscopic forms—coal, ash, graphite, diamond. A relatively new form of carbon, nanotubes, is becoming a revolutionary material in many ways. Carbon nanotubes (CNTs), or buckytubes, are microscopic cylindrical cages of carbon atoms. Each nanotube is essentially a giant molecule with a diameter of about one nanometer and usual length of several millimeters. Multi-walled CNTs (which consist of nanotubes inside larger ones) have very little friction between layers. Individually a CNT has a greater strength to weight ratio than steel and can conduct heat and electricity better than copper.
So far the main use for CNTs has been to improve other materials. Adding them to mixture-based materials improves strength and durability, such as making crack-resistant concrete. On their own, however, carbon nanotubes can be much more impressive. Imagine a cable made of carbon nanotubes that extends many miles from the ground to a space station in geosynchronous orbit. Such a lengthy cable made of any other material would break from its own weight if not the tension of securing the space station. The incredible tensile strength of CNTs might make a cable of that magnitude possible. The cable would allow a “space elevator” to climb up into the heavens without need of rockets. Wouldn't it be incredible to ascend into outer space without the huge rocket engines but with a hi-tech elevator?
The electrical properties of CNTs make them attractive for improving electronic products. Recent research indicates that nanotubes could be used to speed up DNA sequencing. Chinese researchers have discovered that a sheet of CNTs can be used as a speaker. When a varying electrical current is applied, the CNTs heat up nearby air accordingly. The changing temperature causes rapid changes in pressure which we hear as sound. Normal speakers use vibration to produce changes in air pressure, and they can be rigid, fragile, and bulky. This new speaker, however, is as thin as paper, flexible as fabric, and turns transparent when stretched. Stretching, bending, and even cutting the CNT sheet into different shapes will not significantly affect sound quality.
Solar panels made with carbon nanotubes are also thin, flexible, and lightweight. These unique properties may one day lead to the replacement of today's thick, heavy, and fragile silicon solar panels. CNTs can not only improve how we obtain energy, but they can help us store it. Paper embedded with CNTs constitutes a “paper battery”. It looks and feels like black paper, but it can store electricity and function at greater temperature extremes than many conventional batteries. Medical researchers are interested in this technology because paper batteries can be powered by blood or urine. Imagine a pacemaker that is charged by blood passing through the heart.
While CNTs have astounding properties, there are some major hurdles in the way of success. The extraordinary capabilities are undermined by defects which can be difficult to prevent at the nano-scale. Over the last ten years the cost (per gram) has gone from $500+ to $50. This decreasing trend is promising, but for now it is still too expensive to produce CNTs in large quantities. About large quantities: it is still very difficult to make nanotubes longer than a few centimeters.
DO HUMANS DREAM OF ELECTRIC CHICKENS?
Have you ever wanted to watch your dreams after you wake up? Brain scanning technology and sophisticated software may eventually enable you to do just that. Japanese researchers have used fMRI scans and specialized software to reconstruct 100 pixel images viewed by test subjects. The software analyzes brain signals while a person is looking at a set of pictures to learn how pixels are translated into neurological activity. After this “training” the software can roughly recreate still images viewed by the person. The example picture below shows what a person would see (a) and what the software produces just by analyzing an fMRI scan (b). American researchers, including Intel, are using this technique to study word associations. Instead of images, their software figures out what words are in a person's mind.
Possibly the most ambitious goal for this technology is to record dreams. Perhaps sometime this century people will have dreaming caps to wear to bed. The hi-tech headsets scan brain activity and transmit to a computer that translates the scans into video format. When you wake up, you can watch your dreams as if they were movies. No more struggling to remember what crazy things happened. Just play the video file.
This possibility should interest psychologists and psychiatrists. Dreams have long been considered a window to the subconscious mind. Dream interpretation should be a lot easier and more effective if the doctors could see their patients' dreams firsthand. If the mind-reading software could add emotion information alongside dream imagery, then doctors would have a great wealth of information to analyze.
Another exciting possibility is a revolution in the art world. With such technology you could just imagine a painting, and a computer could save the image. You would not need to learn how to paint! Dreams might be uploaded to the internet, maybe gaining viral video status. Movies could be made simply by visualizing them. If software could recreate sound from the mind, then music could be produced without the use of musical instruments. The revolution would stem from lack of need to learn hands-on skills to make art. What would the future hold for art suppliers and classically trained artists? I think the change would be similar to that of the paper media industry today. Newspapers, magazines, and book authors no longer need to print their content on paper. Much of today's media content is published on the internet. Paper media will not go extinct, but it will diminish significantly. In a future when people can make art simply by thinking about it, computer-based media will dominate. However, I do not think traditional media will die out. It will just downsize to a smaller population of artists. This future technology might even help traditional artists via feedback. One could visualize countless variations on an intended painting before deciding on a finished design. Instead of drawing thumbnail sketches an artist could look at a computer screen displaying mental images. The artist then knows with precise detail what the finished paining should look like before a drop of paint has been used.
Such wondrous technology comes with its questions and worries. Do we dream in a particular resolution? How many minutes of a dream pass in a minute of real time? How will this technology affect popular culture and society as a whole? Is our privacy at risk when computers can know what we are thinking about? I am not very concerned about this last question. I do not think fMRI scans could be taken at a distance. The limited range of magnetic fields should prohibit remote scanning. I remember seeing an interesting scenario in Batman: the Animated Series when I was a kid. In the episode “The Strange Secret of Bruce Wayne” a mad scientist invents a machine that tape records people's visual thoughts. The scientist invites public officials and wealthy individuals to his laboratory for psychiatric therapy. Once he finds out his clients' dirty secrets, he uses their recorded thoughts to blackmail them. When Bruce Wayne tries the therapy, the scientist records his thoughts about wanting revenge for the murder of his parents and becoming Batman. The scientist intends to auction the revealing tape to Batman villains, but Wayne secretly uses the invention to record an imagined video of the scientist saying he will swindle the villains with a false tape. This episode poses the possibility of such technology used for blackmail, but the issue is solved by the invention's own versatility. Since blackmail material is easily fabricated, “evidence” cannot be given any credibility.
NEUROLOGICAL CARTOGRAPHY
There is a scientific project underway to map and study the human brain's complex system of interconnected communication pathways, or “circuitry”. This ambitious endeavor is called the Human Connectome Project. Multiple imaging technologies will be employed over the course of five years to get a detailed three-dimensional perspective on our most complicated organ. Just how detailed? A million neurons would comprise the smallest unit of 3D detail, a voxel.
So we are still far from noninvasively imaging the individual neurons, but this project is about larger scale communication. As the data is shared throughout the scientific community, we should get some conceptual breakthroughs in the coming years. The better we understand the brain, the better we can help victims of neurological diseases.
Back to individual neurons. Imagine the future prospect of imaging technology that could see such detail, plus synapses. If we could make a 3D model of the brain that detailed, then it is only a matter of time (a long time) before simulation occurs. Run a computer simulation of a brain, and you have a limitless resource for neurological experiments. If you provide sensory information for the simulation, then the result would be artificial intelligence, right? The possibilities are astounding. What if you could take a snapshot of your brain? The arrangement of your neurons and their connections, the synapses, plays a significant role in your personality and thought processes. Comparing such snapshots could reveal amazing insights into how we think. With a sufficiently sophisticated simulation, such a snapshot could be turned into something of an intelligence clone. Forget programming computers. Maybe far in the future you could just get your brain scanned, and upload the data into a computer. The computer runs a simulation based on the data, thereby becoming artificially intelligent! The virtual brain just needs high-tech sensors and some way of interacting with the physical world. Perhaps not even that. You could create a virtual reality for the simulated brain with which to interact.This prospect creates some intriguing scenarios. First, people's personalities can be immortal. After you die, a computer can continue thinking just like you for the lifetime of its software. Second, there might emerge a race of inorganic people. Their “lives” are not limited by physical bodies. A robot body can be more easily maintained than a biological body. Also, if they get bored with their bodies, then they can just download themselves into other bodies. Another scenario involves a change in perspective. What would be your first reaction if you found out that you were a computer simulation? Those memories, your personality, your emotions, they are just copies of those belonging to some organic life form. You are trapped in an inorganic, virtual world controlled by the guy at the keyboard. That's what it might be like for the computer simulation.
WHEN TWO KIDNEYS JUST AREN'T ENOUGH
What happens when someone's kidneys fail to function at a sustainable level? Dialysis or transplantation. For many people in developed countries, kidney dialysis involves frequent trips to hospitals and spending hours per visit connected to a machine. The dialysis machine slowly filters waste and other toxins out of a patient's blood, thus taking the job of the failed kidneys.
Kidney transplants are far from an ideal remedy as well. First of all, many people who need transplants will not get them. There are fewer donated kidneys than people who need them. Secondly, a transplanted kidney runs the risk of rejection from the patient's body. For this reason, the patient must take immunosuppressive drugs for the rest of his/her life. The blood will be cleaned, but the tradeoff is a greater vulnerability to infection.
One solution to these problems would be an artificial kidney implant that replaces a failed natural kidney. Since it is manufactured, such an implant would compensate for the limited supply of donated kidneys. An implant, being inorganic, would not require drugs to compromise a patient's immune system.
A noninvasive solution would be a portable dialysis machine. A “wearable kidney” would eliminate the need for surgery, and so it would probably be much safer. The current design is worn like a belt. Such a device would have a lot of potential. If it were affordable and easy to use, then its group of users would exceed victims of kidney failure. People who just had reduced kidney function could employ this simple treatment. What about poison victims? Anyone with dangerously high levels of toxins in their blood could be easily helped.
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