by Michael S. Wisz

    "When Nicole entered chicken, potatoes, and spinach into her own computer, a listing of keyboard commands which represent the complex chemicals in these particular foods was printed out on her output buffer. After I signaled that we were ready, she typed that string of commands on the keyboard. They were immediately received here, and what we saw was a response..."
    - from Arthur C. Clarke's Rama Revealed

    Is Clarke a visionary on the wonders that nanotechnology will bring us, truly realizing what the future holds, or another blindly speculating science fiction writer? In Rama Revealed, the human characters interact with an advanced civilization, obtaining food and other goods by entering their chemical components into a computer. The "nanofactory" that was just discovered in this scene reveals how the necessary raw materials are gathered and processed, resulting in outputs of food, paper, electronics, and even toys for the children. Will this be the standard personal computer in the home of the future, or is this too much the stuff of science fiction and fantasy? Perhaps people asked this same question when someone imagined circling the earth, or building a flying vehicle, or journeying to the moon. All these possibilities were realized, just as nanotechnology's will be. Clarke, like all good science fiction writers, includes scientific basis for his imaginings, sensing that technology's rapid progress will someday bring his ideas to life.

    Since nanoassemblers could build just about anything atom by atom, if given the right instructions and raw materials, how would this change the world? First, there is no human labor needed to build the replicating assemblers, since they are by definition self-replicating. Also, the need for industrial factories and land is eliminated, since the raw materials required can be easily found in dirt and air, and the average sized production system could fit in the closet of every home. As for the humans' food production device in Rama Revealed, such a system will also be possible. Since the cells forming food grow in certain patterns in plants and animals that can be duplicated by nanomachines, the present practice of killing animals for consumption will be eliminated. This all translates into a world free of polluting smokestacks, free of hunger and poverty. Even though there will be costs in designing and regulating the unique material possessions that nanotechnology promises, compared to today's costs it will seem like anybody can have anything.

  This may seem a strange way to begin an article, foretelling the solution to some of our world's most daunting problems, seemingly leaving little room to see what other possible wonders nanotechnology can bring us. However, the ordering is indeed appropriate, because nanotechnology may bring about such a panacea as its first step, and then go beyond the imaginations of even the best science fiction writers.

Getting fiction out of the way
    Before foretelling all the amazing things nanotechnology can do for us-in computing, medicine, materials, and space exploration-it is important to realize what nanotechnology cannot do. Nature always imposes certain physical limits on all technologies, and nanotechnology certainly cannot exceed these limits. Even though there will be those who predict many wonderful developments through nanotechnology, there will also be those who make false claims about what nanotechnology is capable of, those who make mistakes, or those out to deliberately fool people.
    Certain problems are beyond nanotechnology's power to solve. Since humans started deforesting land and killing off species, genetic information has been irrevocably lost, perhaps even beyond the point of us bringing the species back to life by recovering the lost genes. And although nanotechnology will revolutionize agriculture, easily having the potential to provide everyone with adequate food, the earth's resources have finite limits. If the population keeps growing exponentially because of better medicine and increasing life spans, humans will need to branch out into space where resources and room to grow is plentiful. Nanotechnology may bring us closer than ever to the physical limits imposed on us, but it cannot change them.

Transforming the Earth
    Think for a moment about a tree, growing silently and noiselessly, in a forest. It takes in water and solar energy for its fuel, and gives off mostly water and oxygen as waste products. What started out as a tiny seed containing the genetic program for the tree's growth now branches out to cover an area the size of a house. You might say nature is well-versed in nanotechnology. The cells of the tree are its replicating assemblers, dividing exponentially on instructions from DNA, a bottom-up approach used in all of nature's "factories".

    Pollution will be a thing of the past with the dawn of nanotechnology. The present plundering of the planet's resources only to release harmful by-products back into the biosphere will be seen as a shameful part of human history. Today's approach of manufacturing from the top-down (i.e., cutting down trees for wood, or mining to obtain metals), will be replaced with molecular manufacturing, the idea that we can build an object from its component molecules. Since we understand the molecular building blocks of most materials, such as wood and steel, we can manufacture them molecule by molecule, but make them even stronger and lighter than their counterparts in nature. With the power to control matter, molecular manufacturing will make materials with a strength-to-weight ratio of a hundred times that of steel, perhaps made of pure diamond. With the solar energy of the nanotechnology age becoming cheaper and more efficient than ever, the manufacturing process will only use clean energy and release harmless by-products such as water and oxygen, just like nature's trees.

    In order to clean up the mess we have already made, we will live off our garbage for a while. Since most materials are made of carbon, such as the polymers of wool, polyester, wood, and nylon, as well as the best structural materials like diamond, nanotechnology will make much use of this plentiful element. Indeed, "mining" the over 300 billion tons of CO2 that will have been spewed out into the atmosphere since the Industrial Revolution will provide enough carbon to build strong and lightweight housing for every family in a population of 10 billion. And with 95% of this CO2 left over, endless necessities can be manufactured without even scratching the earth's surface!

    After cleaning up the long polluted atmosphere, the human race can work to restore the land and the waters back to their natural state. Where once there was a 20th century factory contaminating the soil around it with toxic chemicals, there will be grass and forests again. Where once there was a polluted lake, useless for fishing or swimming on a hot summer day, there will be pristine waters again, untainted by waste. These visions can become reality with nanomachines having the ability to pick out the toxic molecules one by one and converting them to harmless compounds, a power unavailable today. Once the cleanup has been completed, the earth can remain in this state for years to come with "clean as a tree" molecular manufacturing.

    These previous examples, as well as the ones that follow, consistently reveal nanotechnology to be efficient, clean, and precise, as can be expected once we have control over matter on the smallest of scales. Today's agriculture is one of the best examples of a wasteful, polluting, inefficient enterprise that nanotechnology can turn around. Synthetic fertilizers, herbicides, and pesticides tarnish land and water in an effort to feed a growing population while hunger continues. Forests are being cut down at an alarming rate, destroying entire ecosystems, especially in the bio-rich rain forests. With nanotechnology, greenhouses patrolled by "nanoflyswatters" would render pesticides unnecessary, and plants could be provided with any necessary nutrients, conditions often lacking in the uncontrollable outside environment. The plants would thrive in the high humidity, uniform temperature, carbon dioxide atmosphere of the molecularly manufactured greenhouse, making food of the future much more inexpensive than today. With greenhouses, each person would require a mere 250 square meters of food per year, and 97% of today's farmland can be returned to nature. Using a much smaller fraction of their land to grow food, farmers will find that it is in their best interests to convert it to a park or wilderness, and actually look for ways to please nature lovers!

 Left: A molecular model of a hinge, produced by CrystalClear software.

    Today, as forests are slashed and burned, precious biodiversity and genetic information is lost, the products of millions of years of evolution, erased from existence. This is the tragic case for most species destroyed in the rain forests, but for those lucky few whose genes are preserved, nanotechnology has the potential to bring them back to life. It has been long known that genes can survive in dried skin, bone, horn, and eggshell for many years, but present technology is unable to do anything with this knowledge. Still, the BioArchive project plans on gathering biological samples for future species restoration, for a time when cell surgery techniques and molecular repair (discussed in the "Medicine" section) will enable us to transform lifeless DNA into living creatures once again.

Computers
    An obvious route when thinking about the very small is to shrink the size and cost of computers, and speed their operation phenomenally. Today's technology relies on etching patterns on silicon so that tiny electronic switches can be turned on and off, the basis for the binary code that represents everything the computer understands. Tomorrow's nanocomputers will have molecular switches, or logic rods, to replace today's electronic kind (perhaps initially). The rods will be made up of carbyne, a chain of carbon atoms linked by double and triple bonds, and depending on their positions, will encode a value of 0 or 1. Even though the motion of sliding rods is 100,000 times slower than electronic switches, the mechanical messages will only need to travel 1/1,000,000 as far, thus giving mechanical nanocomputers the edge. A simple nanocomputer could fit in a box 1/100 of a cubic micron, and a more complex version with gigabytes of storage could fit in a box a micron wide (the size of a bacterium!). The size difference between today's "microcomputers" and tomorrow's nanocomputers is much more extreme than the comparison between the first one-room vacuum tube systems with today's computers.

    Yet these mechanical nano computers just described, already much faster than electronic computers of the 1990's, will seem like so many clunky mechanical rods compared to the electronic nanocomputers of the future, which will rely on quantum mechanical effects for their operation. Indeed, by the time we have the technology to build nanocomputers, we may entirely bypass the mechanical version, seeing them instead as a lower limit on performance. While electrical nanocomputers will mean the ultimate for speed, for power, nothing will stop future engineers from packing a trillion of these computers in a space no bigger than a present day microchip. For storage it will be possible, say, to use "atomic tape", a spool of atoms representing 1's and 0's, with enormous information density, allowing such marvels as "pocket libraries". In this light, the so-called miniaturization of today's computers is paltry.

Medicine
    From a cell's point of view, today's surgery seems pretty barbaric: a huge blade cuts through a crowd of cells, killing thousands. A thick cable is dragged in to sew up the damage, leaving it up to the cells to abandon their dead and multiply, so that healing can take place. Now imagine, from the cell's point of view, the administration of a drug to a patient. The drug molecules bump aimlessly around until they fit into their target molecule, identifying specific molecules by "touch." With this in mind, think about what can be done with a molecular machine that can sense, plan, and act at this level, armed with a nanocomputer that contains data on the structure of all healthy tissue. Repair machines the size of a bacterium can be built to enter and leave cells, destroy intruders in the blood vessels, and even check the DNA itself for any errors!

    To begin with the simplest type of these "engines of healing," as nanotechnology pioneer K. Eric Drexler has coined them, envision a "nanosubmarine" cruising the blood vessels of the human body, absorbing glucose and oxygen for energy to drive its two helical propellers. There will be no need for any guidance system, since sensors on the front of the sub will let it try a different path if it has bumped into something, The sub has no need to go in any particular direction, since its only purpose would be to engulf any hostile bacterium or virus in its way. It will break down and release anything that its nanocomputer has been programmed for, including unwanted fat deposits. A fleet of such nanosubs could certainly cleanse the body of any unwanted impurities!

    On a higher level of complexity are cell repair machines. Today, when a cell is damaged, doctors rely on drug molecules and the cell's ability to repair itself, even though this process does not always bring the patient back to health. With future nanodevices, repair on the smallest components of the cell will even permit future doctors to restore cells that have been damaged to the point of inactivity. These machines will be able to get to the root of the problem, literally rebuilding damaged molecules inside the cell. To picture the scale of these wonders, enlarge the cell so that each of its atoms is the size of a marble. On this scale the cell is one kilometer across, and the repair machine is one-millionth of the cell volume, about the size of a three-story house! Each machine has its own nanocomputer with more information than the cell's DNA in a space the size of a small truck, and its smallest tools are the size of your fingertip. A group of these repair devices are all connected to a larger, cubic micron computer the height of a thirty-story building and the width of a football field.

    Realizing that the human body contains about ten thousand billion billion protein parts, all part of an extremely complex machine manifesting itself as life, can future cell repair machines really improve on what nature has accomplished through evolution? The first cell repair machines will likely be quite specialized, entering a cell, examining the activity inside, and correcting a single type of problem, such as an enzyme deficiency or some simple kind of DNA damage. However, as the technology advances, the machines will be able to repair breaks and cross-links in the DNA, actually correcting "misspellings" in the sequence, using correct copies from many cells as a template. To perform other repairs, the machine's nanocomputer will have to have information on what differentiates a healthy cell from a damaged cell. If a specific molecule is targeted, the device will need a mechanism to "recognize" different molecules, just as antibodies identify proteins by touch. Again, it will make use of the vast information resources available to it inside its nanocomputer to quickly read the amino acid sequence and differentiate between the roughly 100,000 human proteins. The power of nanocomputers is such that in the time it takes a typical enzyme to change a single bond, the computer will have performed over one-thousand computational steps! Clearly, the human built repair devices will win in speed over nature's molecular machines. But can they beat nature's ability to fight diseases and poisons in the body? Yes, with the ability to cure even unknown diseases. Since there are many more ways that the human body can be sick than it can be healthy, if researchers learn how to describe in detail every organ in its healthy state, then the nano-repairers will only need to look for differences from this description to establish a state of health. And even the complex human brain is not excluded from the power of nano-repair devices. Repair on individual synapses would not be too complicated, since their structure is already known, and eventually it should be possible to obtain a mapping of the entire brain. Mind-downloading, anyone?

    Nanotechnology will clearly revolutionize medicine, giving humans the ability to extend their lives. Since death can be considered as a disease resulting from damaged molecular machinery, chemical imbalances, and misarranged structures, all problems within the range of nano-repair devices, youthful health may well be restorable. Let us hope we use this extra time to good advantage.

 Right: photo courtesy of FASA Corporation

Space
    How will tiny machines on the nanometer scale propel the human race to the scale of light years and beyond? Once the nanotechnology revolution arrives and transforms the earth into a veritable paradise, humans may want to expand into the final frontier. Nanotechnology will greatly ease this venture.

    First, we must shed the old-fashioned idea, dating back to Chinese fireworks, that we must explore the solar system and beyond with fuel burning rockets. Instead of thinking about powerful blasts propelling spacecraft, consider smaller forces, such as sunlight, gradually pushing a vehicle to increasing speeds, i.e. solar sails. Indeed, the idea of a solar sail has already occurred to NASA space engineers, an idea that will become a reality through nanotechnology.

    Just as sailboats have traversed the seas for centuries carrying their travelers to unknown lands using nothing but the power of wind, solar sails will use the sun's light energy to traverse space. However, instead of the canvas that makes up our earthly sails, the light sails will be composed of reflective panels. And rather than crossing distances on the scale of hundreds of kilometers, these sails will cross interstellar distances! This would normally take thousands of years slowly accelerating, but if we can give our sail a big push via an array of lasers driving a beam to its surface, near light speeds and the stars can be reached (analogous to a powerful "wind" our explorer ancestors no doubt wished for). The high performance sails will resemble spider webs, kilometers in diameter, made of graphite fiber strands bridged by reflecting panels thinner than a soap bubble. Their fragile nature will require them to be built in space, and this is where nanomachines will enter the picture. Just as a leaf grows on earth, the sail will gradually take shape as thousands of replicating assemblers use the sun's energy to build it, filling in the gaps of the structure with raw materials brought up from earth or mined from a nearby asteroid.

    The space closely surrounding the earth, never mind journeys to the stars, contains room enough for the human race to grow. Consider replicating systems being able to build huge, rotating cylindrical worlds filled with soil, streams, forests, and sunlight. With strong carbon-based materials (i.e. diamond) perhaps mined from some asteroid (one of these wandering mountains a kilometer-wide has enough precious metals worth several trillion dollars), and ample water from one of the ice moons of Saturn, Uranus, or Neptune, replicators could use the sun's energy to build projects on a truly mega scale! Imagine a sphere, built by nanomachines, completely surrounding the solar system, taking advantage of all the energy the sun puts out. Presently, 99.999999955% of this energy misses earth. Every second the "Dyson sphere", named after Freeman Dyson who proposed that very advanced civilizations might possess it, would collect 1,000 times the energy every second the human race produces in one year! The necessary material for a sphere a few millimeters thick made of solar panels could be manufactured using but one average sized asteroid. Nanomachines even have the capability to let us see deeper into the universe, letting us build a telescope of unprecedented size, and with unparalleled accuracy. Because of nano-technology's bottom-up, atom by atom approach to construction, the telescope's mirror could be built to exact specifications, flawlessly. Since the mirror itself could contain tiny nanocomputers in its structure, it could change shape in response to the sun's rays heating it unevenly, or perhaps repair itself if struck by space debris!

    Astronomy and space exploration will be revolutionized under nano-technology's influence. More humans will move onto "floating" worlds in earth orbit, or onto colonies built on Mars or the moon. Launches into space will become as commonplace as flying an airplane when molecular manufacturing makes launch vehicles that are light and strong, and developments in "smart" materials will lead to a rocket that can change its aerodynamic shape upon launch and reentry for maximum efficiency. As people from earth begin to fan out to the stars, many may well wonder how so many people lived for so long without the benefits of nanotechnology.

Looking farther ahead still
    Just how long will it take to make the advances this article speculates on? With our current level of development, some of the ideas here could take hundreds, maybe thousands of years, for humans to realize. However, this estimate neglects the growing power of artificial intelligence (AI), an influence that will drastically change the way we think about technical breakthroughs.

    Today, advancements are being rapidly made in the area of machine intelligence. Although computers have long been thought of as mere calculating devices, only capable of performing repetitive tasks, AI researchers argue that computers can be made smart, standing behind computers that can beat chess grand masters. Machines with the human-like ability to learn and organize knowledge will become more and more common, and automated engineering will speed the development of newer nanomachines faster than a human engineering team ever could. It will come to the point where computers will be designing computers, building increasingly better systems with each generation. Eventually, the ultimate goal of building a computer to resemble the human brain itself will be attempted. Just as a photocopier can transfer words from paper to paper without understanding them, neurobiologists will copy the brain's structure without understanding its overall organization. The advanced nanomachines and nanoelectronics will mimic the behavior of the synapses, only a million times faster. Because each synapse of the brain is much more than just an on-off switch, actually changing its structure in the learning process, each artificial synapse will be surrounded with nanocomputers telling nanomachinery how to modify the switch for each response. And although 1 cubic centimeter seems extremely small for a computer of this complexity, consider that this is 1012 times larger in volume than the cubic micron nanocomputer mentioned earlier!

    Although it may seem like nanotechnology offers such a cornucopia of benefits, the human race must not let its potential destructive powers obliterate all that might be gained. The implications of using nanotechnology for aggressive purposes are far more foreboding than previous weapons, and must always be checked. Molecular manufacturing makes it possible to build weapons at a much faster rate than is now possible, but a more frightening prospect is the development of dangerous programmable "germ" nanomachines for warfare. The possibility of accidental world destruction also exists, if one thinks about the implications of escaped replicating machines eating organic materials throughout the earth. Indeed, nanotechnology in the wrong hands could have disastrous consequences, but even those responsible for its beneficial use must be wary of the potential dangers.

    At first, nanotechnology will be more technically challenging than other weapons. Nanoterrorism will not be possible for many years to come, until the knowledge on how to build replicating assemblers becomes more available. However, to stop powerful nations from using nanotechnology's destructive power, some regulations will have to be made. If enough time is allowed for all the peaceful developments to succeed, then hopefully we will be capable of averting any aggressive actions. To prevent accidents, such as the replicators on the loose scenario, safeguards can be made and built into all replicators. Drexler, for example, proposes that we must "never make a replicator that can use an abundant natural compound as fuel." If we can control the power of nanotechnology, there is much to hope for.

    If we succeed in wisely using nanotechnology's potential, the future will be a bright and rich one indeed. The science fiction of today will become tomorrow's reality, The end of the world as we know it approaches, with the new world of nanotechnology visible on the horizon. Let the nanotechnology race begin!

About the Author...
Michael S. Wisz, a junior studying Physics in the Arts & Sciences College, knows the importance of stretching before doing a problem set.