The properties of materials depend on how their atoms are arranged. Rearrange the atoms in coal and you get diamonds. Rearrange the atoms in soil, water, and air, and you have grass. And since humans first made stone tools and flint knives, we have been manipulating atoms in great thundering statistical herds by casting, milling, grinding, and chipping materials. We rearrange the atoms in sand, for example, add a pinch of impurities, and we produce computer chips. We have gotten better and better at it, and can make more things at lower cost and with greater precision than ever before.
Even in our most precise work, we move atoms around in massive heaps and untidy piles-millions or billions of them at a time. Theoretical analyses make it clear, however, that we should be able to rearrange atoms and molecules one by one-with every atom in just the right place-much as we might arrange Lego blocks to create a model building or simple machine. This technology, often called nanotechnology or molecular manufacturing, will allow us to make most products lighter, stronger, smarter, cheaper, cleaner, and more precise.
The consequences would be great. We could, for starters, continue the revolution in computer hardware right down to molecular-sized switches and wires. The ability to build things molecule by molecule would also let us make a new class of structural materials that would be more than 50 times stronger than steel of the same weight: a Cadillac might weigh 100 pounds; a full-size sofa could be picked up with one hand. The ability to build molecule by molecule could also give us surgical instruments of such precision and deftness that they could operate on the cells and even molecules from which we are made.
The ability to make such products probably lies a few decades away. But theoretical and computational models provide assurances that the molecular manufacturing systems needed for the task are possible-that they do not violate existing physical law. These models also give us a feel for what a molecular manufacturing system might look like. This is an important foundation: after all, the basic idea of an electrical relay was known in the 1820s, and the concept of a mechanical computer that operated off a stored set of instructions-a program-was understood a few years later. But computers using relays were not built till much later because no good theoretical comprehension of “computation” existed. Today, scientists are devising numerous tools and techniques that will be needed to transform nanotechnology from computer models into reality. While most remain in the realm of theory, there appears to be no fundamental barrier to their development.