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Wireless nanocrystals, a.k.a. quantum dots, efficiently emit visible light. Source: Los Alamos National Laboratory.
Manufactured products are made from atoms. The properties of those products depend on how those atoms are arranged. If we rearrange the atoms in coal, we get diamonds. If we rearrange the atoms in sand (and add a pinch of impurities) we get computer chips. If we rearrange the atoms in dirt, water and air we get grass.
Since we first made stone tools and flint knives we have been arranging atoms in great thundering statistical herds by casting, milling, grinding, chipping and the like. We’ve gotten better at it: we can make more things at lower cost and greater precision than ever before. But at the molecular scale we’re still making great ungainly heaps and untidy piles of atoms.
That’s changing. In special cases we can already arrange atoms and molecules exactly as we want. Theoretical analyses make it clear we can do a lot more. Eventually, we should be able to arrange and rearrange atoms and molecules much as we might arrange LEGO blocks. In not too many decades we should have a manufacturing technology able to:
- Build products with almost every atom in the right place.
- Do so inexpensively.
- Make most arrangements of atoms consistent with physical law.
Often called nanotechnology, molecular nanotechnology or molecular manufacturing, it will let us make most products lighter, stronger, smarter, cheaper, cleaner and more precise.
The advantages of nanotechnology
One of the basic principles of nanotechnology is positional control. At the macroscopic scale, the idea that we can hold parts in our hands and assemble them by properly positioning them with respect to each other goes back to prehistory: we celebrate ourselves as the tool using species. Our wisdom and our knowledge would have done us scant good without an opposable thumb: we’d still be shivering in the bushes, unable to start a fire.
At the molecular scale, the idea of holding and positioning molecules is new and almost shocking. However, as long ago as 1959 Richard Feynman, the Nobel prize winning physicist, said that nothing in the laws of physics prevented us from arranging atoms the way we want: “…it is something, in principle, that can be done; but in practice, it has not been done because we are too big.”1
What would it mean if we could inexpensively make things with every atom in the right place?
- For starters, we could continue the revolution in computer hardware right down to molecular gates and wires — something that today’s lithographic methods (used to make computer chips) could never hope to do.
- We could inexpensively make very strong and very light materials: shatterproof diamond in precisely the shapes we want, by the ton, and over fifty times lighter than steel of the same strength.
- We could make a Cadillac that weighed fifty kilograms, or a full-sized sofa you could pick up with one hand.
- We could make surgical instruments of such precision and deftness that they could operate on the cells and even molecules from which we are made — something well beyond today’s medical technology.
The list goes on — almost any manufactured product could be improved, often by orders of magnitude.
What will we be able to make?
Nanotechnology should let us make almost every manufactured product faster, lighter, stronger, smarter, safer and cleaner. We can already see many of the possibilities as these few examples illustrate. New products that solve new problems in new ways are more difficult to foresee, yet their impact is likely to be even greater. Could Edison have foreseen the computer, or Newton the communications satellite?
1. Improved transportation
- Today, most airplanes are made from metal despite the fact that diamond has a strength-to-weight ratio over 50 times that of aerospace aluminum. Diamond is expensive, we can’t make it in the shapes we want, and it shatters. Nanotechnology will let us inexpensively make shatterproof diamond (with a structure that might resemble diamond fibers) in exactly the shapes we want. This would let us make a Boeing 747 whose unloaded weight was 50 times lighter but just as strong.
- Today, travel in space is very expensive and reserved for an elite few. Nanotechnology will dramatically reduce the costs and increase the capabilities of space ships and space flight.2 The strength-to-weight ratio and the cost of components are absolutely critical to the performance and economy of space ships: with nanotechnology, both of these parameters will be improved…3 Beyond inexpensively providing remarkably light and strong materials for space ships, nanotechnology will also provide extremely powerful computers with which to guide both those ships and a wide range of other activities in space.
2. Atom computers
- Today, computer chips are made using lithography — literally, “stone writing.” If the computer hardware revolution is to continue at its current pace, in a decade or so we’ll have to move beyond lithography to some new post lithographic manufacturing technology. Ultimately, each logic element will be made from just a few atoms.
- Designs for computer gates with less than 1,000 atoms have already been proposed — but each atom in such a small device has to be in exactly the right place. To economically build and interconnect trillions upon trillions of such small and precise devices in a complex three dimensional pattern we’ll need a manufacturing technology well beyond today’s lithography: we’ll need nanotechnology.
- With it, we should be able to build mass storage devices that can store more than a hundred billion billion bytes in a volume the size of a sugar cube; RAM that can store a mere billion billion bytes in such a volume; and massively parallel computers of the same size that can deliver a billion billion instructions per second.
3. Military applications
- Today, “smart” weapons are fairly big — we have the “smart bomb” but not the “smart bullet.” In the future, even weapons as small as a single bullet could pack more computer power than the largest supercomputer in existence today, allowing them to perform real time image analysis of their surroundings and communicate with weapons tracking systems to acquire and navigate to targets with greater precision and control.
- We’ll also be able to build weapons both inexpensively and much more rapidly, at the same time taking full advantage of the remarkable materials properties of diamond. Rapid and inexpensive manufacture of great quantities of stronger more precise weapons guided by massively increased computational power will alter the way we fight wars. Changes of this magnitude could destabilize existing power structures in unpredictable ways. Military applications of nanotechnology raise a number of concerns that prudence suggests we begin to investigate before, rather than after, we develop this new technology.4
4. Solar energy
- Nanotechnology will cut costs both of the solar cells and the equipment needed to deploy them, making solar power economical. In this application we need not make new or technically superior solar cells: making inexpensively what we already know how to make expensively would move solar power into the mainstream.
5. Medical uses
- It is not modern medicine that does the healing, but the cells themselves: we are but onlookers. If we had surgical tools that were molecular both in their size and precision, we could develop a medical technology that for the first time would let us directly heal the injuries at the molecular and cellular level that are the root causes of disease and ill health. With the precision of drugs combined with the intelligent guidance of the surgeon’s scalpel, we can expect a quantum leap in our medical capabilities.5
The single most frequently asked question about nanotechnology is: How long? How long before it will let us make molecular computers? How long before inexpensive solar cells let us use clean solar power instead of oil, coal, and nuclear fuel? How long before we can explore space at a reasonable cost?6
The scientifically correct answer is: I don’t know.
From relays to vacuum tubes to transistors to integrated circuits to Very Large Scale Integrated circuits (VLSI) we have seen steady declines in the size and cost of logic elements and steady increases in their performance.7
- Extrapolation of these trends suggests we will have to develop molecular manufacturing in the 2010 to 2020 time frame if we are to keep the computer hardware revolution on schedule.
- Of course, extrapolating past trends is a philosophically debatable method of technology forecasting. While no fundamental law of nature prevents us from developing nanotechnology on this schedule (or even faster), there is equally no law that says this schedule will not slip.
- Much worse, though, is that such trends imply that there is some ordained schedule — that nanotechnology will appear regardless of what we do or don’t do. Nothing could be further from the truth. How long it takes to develop this technology depends very much on what we do. If we pursue it systematically, it will happen sooner. If we ignore it, or simply hope that someone will stumble over it, it will take much longer. And by using theoretical, computational and experimental approaches together, we can reach the goal more quickly and reliably than by using any single approach alone.
While some advances are made through serendipitous accidents or a flash of insight, others require more work. It seems unlikely that a scientist would forget to turn off the Bunsen burner in his lab one afternoon and return to find he’d accidentally made a Space Shuttle.
Like the first human landing on the moon, the Manhattan project, or the development of the modern computer, the development of molecular manufacturing will require the coordinated efforts of many people for many years. How long will it take? A lot depends on when we start.
© 1997, Ralph C. Merkle. Abridged version of an article first published in the Feb/Mar issue of MIT Technology Review. © 2009, American Institute of Biological Sciences. Educators have permission to reprint articles for classroom use; other users, please contact email@example.com for reprint permission. See reprint policy.