What Is Nanotechnology?

Nanotechnology is the science of creating molecular-size machines that manipulate matter one atom at a time. The name comes from nanometer--one one-billionth of a meter--which is roughly the size of these tiny devices.

The idea dates back to a 1959 speech by physicist Richard Feynman in which he proposed manipulating matter atom by atom and was championed most famously in K. Eric Drexler's 1986 book Engines of Creation.

WHAT ARE NANOBOTS?

Nanobots are the workhorses of the nano-manufacturing world. They are, as the name implies, nanometer-scale robots that use tiny arms to pick up and move atoms and tiny electronic brains to direct the process. There are two basic types of nanobots: general assemblers and a special class of assemblers known as self-replicators.

ASSEMBLERS These cell-size robots may be equipped with fingers for manipulating matter, probes for distinguishing one atom or molecule from another and programs to tell the robots what to do.

SELF-REPLICATORS To build anything of any size, you need a lot of assemblers, and constructing them one by one is expensive and laborious. So most assemblers will need the additional ability to make copies of themselves. To make a skyscraper, for example, a handful of assemblers would first clone themselves into an army of trillions of tiny robots, then start building (see NIGHTMARE SCENARIO).

THE TWO SIDES OF MANUFACTURING The conventional approach is top-down: starting with large clumps of steel, wood, plastic, masonry and shaping them into the forms you want. Nanotechnology is, by contrast, bottom-up: stacking individual atoms into useful shapes. We know that the bottom-up approach is possible because that's what biology does, assembling proteins from individual atoms and molecules, putting them together to form cells and layering cells upon cells to form large, complex objects such as sperm whales and giant Sequoia trees.

THE APPLICATIONS

Everything in the physical world is made of atoms. Nanobots manipulate atoms. Thus nanobots could in principle make anything from apples to airplanes. Nanobots will probably be made from carbon nanotubes, a new form of carbon that is astonishingly versatile.

NANOTUBES Carbon molecules form a hexagonal mesh that curls into a cylinder like a tube of chicken wire. About 100 times as strong as steel and 50,000 times as thin as a human hair, they can serve as the structure of a nanobot. Acting as semiconductors, nanotubes are also ideal for building a nanobot's tiny microprocessor brain.

ELECTRONICS The advantages of smaller computers--more speed, more memory--are well known. But building matchbox-size supercomputers is too delicate a job for conventional mass manufacturing. Nanobots could do it easily, laying down circuits (made of nanotubes) molecule by molecule without a single mistake.

FUTURISTIC MATERIALS A diamond's extraordinary clarity and strength make it an ideal building material, but also terribly hard to work with. Nanobots, however, could make diamonds in any shape at all--a sheet a few millimeters thick, say, to make a scratchproof window. And because the basic feedstock is ordinary carbon, these diamonds are as cheap as glass.

MOLECULAR MEDICINE Streaming through the body by the billions, nanobots could chip plaque from arteries, gang up on bacteria and viruses, scour toxins from the bloodstream, repair broken blood vessels--and dozens of jobs doctors haven't dreamed of yet.

ENVIRONMENTAL CLEANUP Specialized nanobots dumped into an oil spill, a toxic-waste site or even a polluted stream could seek out and find dangerous molecules, remove them or change their chemical structure one by one to render them harmless--or even beneficial.

NIGHTMARE SCENARIO Self-replication is the best way to build a few trillion nanobots in a hurry: each one makes two more, and each of those makes two and so on. But if they don't stop, the entire planet could rapidly be reduced to a teeming mass of robots. Nanotechnologists plan to program their tiny creations to stop reproducing after a certain point. But it takes only one rogue self-replicator to cause a disaster. If you thought computer viruses were a problem...