Ralph C. Merkle - Why you should care about molecular nanotechnology
Nanotechnology: why people care (or: thinking outside the dot)
Ralph C. Merkle
Distinguished Professor of Computing
Georgia Tech College of Computing
Billions are being spent on "nanotechnology," researchers around the world are working on "nanotechnology," and "nanotechnology" companies are seeing their stock prices jump. The term is applied to stain-resistant pants, sun tan lotion, optical lithography, and quite a few other things. As the mania for all things nano continues to escalate, it is important to keep in mind the reasons that make people actually care about nanotechnology (aside from its remarkable ability to make stock prices jump and secure research funding — which are secondary consequences, not primary reasons).
People care about nanotechnology because it can fundamentally improve the human condition by giving us mastery over matter.
More specifically, nanotechnology will let us economically arrange atoms in most of the ways permitted by physical law. (This is sometimes called Molecular NanoTechnology, or MNT, to distinguish it from broader uses of the term "nanotechnology."). This rather dry statement conceals a combinatorial explosion of new possibilities, of new products, of new options, and new hopes. Computers will be orders of magnitude more powerful, materials will be remarkably light and strong, medical technology will be able to heal and cure in cases that today would be abandoned as completely hopeless, the environment will be restored — in short, many of the material dreams of humanity can be fulfilled.
Put more graphically, if we think about all the different ways we can arrange atoms, all the possibilities that the laws of nature permit, it is obvious that today we can make only an infinitesimal fraction of what is possible. All that we have made, all that we could make using the tools that we now have, is truly but a minuscule dot compared with the vast universe of new possibilities.
The infinitesimal dot of what we can make is not what makes people care. It is the vista of new possibilities that we see opening up before us.
If we focus our research on the dot, and ignore the vista — no one will care. Our society already has in place mechanisms for the evolutionary expansion of the dot, for the incremental expansion of what we can make. Society is not going to create new mechanisms, allocate new resources, arouse the excitement of the best and the brightest, when the goal is but a small improvement.
First, of course, we must acknowledge that the dot is vastly larger today than it was when the first humans were making stone tools and chipping flint. While even then we were arranging atoms, we were doing so only in the crudest possible ways and could make only the most limited range of products. As we look about our modern cities, fly across the oceans, see and talk with people on other continents, look curiously at pictures sent back from Mars, enjoy images and sounds that were created in digital computers and never existed in the physical world — we realize the vast gulf between what our ancient ancestors could do and our abilities today.
And then — take a deep breath — realize that the gulf between then and now is, if anything, smaller than the gulf between now and what the coming years will bring.
Today we have computers — supercomputers that it pleases us to think are awesome and powerful. There are perhaps another dozen orders of magnitude between the raw computational power of computers today and the computers we know are possible. A child's toy of the future would put the combined might of all the computers in the world today to shame.
Our cities are built of concrete and steel — yet materials two orders of magnitude stronger are possible. How will this transform our buildings, our cars, our airplanes, our rockets?
We have barely deciphered the genetic code, and our understanding of it is still limited. Our medical tools are large and gross compared with the cells and molecules from which we are made. What happens when our knowledge of medicine has grown, our medical tools are molecular, and are guided by molecular computers? What will happen to medicine? What will happen to our health?
How could we, today, explain the modern world to our ancient ancestor knapping flint and chipping stone? And how can we, today, understand what will be commonplace in years to come? The pace of technology is accelerating, and while the gap between stone axes and television sets is measured in tens of thousands of years; the gap between today and tomorrow will be compressed into decades.
Which brings us back to the dot — the dot of things we can make, the infinitesimal dot lost in the vast space of possibilities. That dot will grow. Today, it grows incrementally around the edges. Today, we think about what we can make, and we think about what we could make in the next few years, and the dot swells in size. Industry, government, academia: today all think about what the dot could become in the near future.
But next year, or the year after, are not what excite the public, nor the students who must decide whether to devote their careers to this new technology, nor the scientists who have seen what is possible.
They are inspired by what is beyond the dot. Instead of asking: what might we make next year, or even in a few years, we must cut to the heart of the matter and ask: what is possible? What is the dividing line between what we will someday make and what we can never make? What are the fundamental limits of manufacturing?
There is precedent: we have thought about fundamental limits in thermodynamics, in information, in space flight. How efficient can a steam engine be? How much information can we transmit over a phone line? Could we go to the moon? All these questions and more were asked and thought about and answered. We should add a new question: what is beyond the dot? What is over the horizon? What lies beyond the straight line extrapolations of the next few years?
In manufacturing, we arrange atoms. Whether by banging two rocks together, or by using lithography to make a computer chip, or any of the other methods we have developed we are arranging atoms into patterns that we find desirable, or useful, or simply pretty. What are the ultimate limits?
Some ask: should we think about what lies beyond the dot? Ancient maps had edges wreathed by sea serpents and monsters, places we dared not go. Should we, today, place sea serpents and monsters at the edges of our understanding, guardians of the unknown, beyond which we dare not think?
This is not a rhetorical question — many would have us walk away from the universe of the possible, turn our backs on the future, and focus on the dot. The dot, after all, defines the realm of what we can do today, and incrementally expanding that realm is a time honored and entrenched tradition — one that has carried us from the stone age to the space age. Why change? Why think beyond the dot? We have a hard enough time thinking about what is within the dot, thinking beyond the dot is harder — perhaps we should ignore it? Perhaps we should content ourselves with evolutionary progress, thinking that this will (at least eventually) bring us mastery of all that we conceive of as possible today?
Progress, though, is neither smooth nor inevitable. Babbage devised the Analytical Engine in the 1830's, yet it was not until over a century later that computers began to change the world. The single most important development of the 20th century was known — and ignored — in the 19th. This is not an isolated incident, but rather part of a more general pattern. New ideas are accepted but slowly. As Machiavelli said, "...This indifference arises ... partly from the incredulity of men who have no faith in anything new that is not the result of well-established experience."
If we are to develop what is new, if we are to build what has never been built, if we are to devise new systems that have no precedent, we must think about them before we can build them. And conveniently at hand is a new tool — the computer — that lets us think with hard edged precision about what the laws of physics permit and what they forbid. Computational models are today accurate enough to let us think about whole classes of new devices — new arrangements of atoms, new products, new ways of computing, new manufacturing systems. Beyond that, the computer lets us see what we have not yet built in a way which can, at least in part, overcome "... the incredulity of men...". A video showing the proposed operation of a new device has a tremendous impact — it can convey new ideas and new concepts in a way that is historically unprecedented. Tsiolkovski had to convey the idea of an orbiting space station with rough sketches, and Goddard was ridiculed for proposing that rockets would work in space (there's no air to push against....) — his abstract equations and appeals to Newton's laws were unable to convey the physical reality with the force that modern simulations and graphics would have achieved.
The question remains: should we think beyond the dot? Or should we walk away?
First, nanotechnology has inspired the public, students, and many scientists because of the vista ahead, because of the universe of possibilities beyond the dot. Inspiration should not be thrown away lightly, it is a rare and precious commodity. Without it, people do not care, resources do not flow, projects are not carried out. The outpouring of support for nanotechnology will vanish if we tell people: We will focus on the dot, and on nothing else. The dot is all.
Second, how can we make what we refuse to think about? If we focus on the dot, we will not think about nor will we ever be able to make those myriad remarkable devices that are well beyond the dot. The future is not preordained, we will not reap the benefits regardless of what we do. The Apollo Project took us to the moon, but if Kennedy had not inspired us, had not set the goal and focused the resources, travel to the moon might yet remain a distant dream. If we do not try, we cannot succeed.
Perhaps an alternative perspective will help clarify the issues: within the framework of well known and well understood physical law, some things are possible and some things are not. Within that framework, we can ask whether we can economically arrange atoms in most of the ways permitted by physical law. We expect one of two answers: either such an endeavor is feasible, or there is some reason that puts it forever beyond our grasp. Either way, we must know.
If this is impossible, we expect a cogent argument that will withstand scrutiny and analysis. No such argument has been advanced.
If this is possible, we again expect a cogent argument that will withstand scrutiny and analysis. There is today a body of research that answers this question in the affirmative, and which has not been contradicted. Indeed, none have shown any significant errors in Drexler's 1992 book Nanosystems, now over a decade old, let alone advanced any fundamental arguments based purely on physical law that show or even suggest impossibility.
If this is possible, we must ask the most important question: how are we to achieve it? What systems will accomplish this goal, what principles should we rely on, what are the mechanisms by which we could carry it out?
Our society — our world — is not asking these questions. A handful of pioneers have concluded that such systems are possible, and are exploring what they might look like. It is now time to move to the next stage: the systematic investigation of these new vistas with the focus and resources necessary to achieve this ambitious goal. The tools are at hand, the questions are known, the methods of investigation are well understood.
How long will it take? We don't know. But we do know that the sooner we begin, the sooner we can reap the benefits promised by this new and fundamentally transformative technology.