At the last turn of the century, the average person would have had a hard time trying to understand how cars and airplanes worked, and computers and nuclear bombs existed only in theory. By the next turn of the century, we may have submicroscopic, self-replicating robots; machine people; the end of disease; even immortality.

Hard to imagine? Not for the new breed of scientist who says that the 21st century could see all these science fiction dreams come true thanks to molecular nanotechnology, a hybrid of chemistry and engineering that would let us manufacture anything with atomic precision. In fact, scientists claim that even within the next 50 years, this new technology will change the world in ways we can barely begin to imagine today. 

Just as computers break down data into its most basic form--1s and 0s--nanotechnology deals with matter in its most elemental form: atoms and molecules. 

With a computer, once data is broken down and organized into combinations of 1s and 0s, it can be easily reproduced and distributed. With matter, the basic building blocks are atoms and the combinations of atoms that make up molecules. Nanotechnology lets you manipulate those atoms and molecules, making it possible to manufacture, replicate, and distribute any substance known to humans as easily and cheaply as you can replicate data on a computer. 

To get an idea of the scale, consider that the basic measuring unit in nanotechnology, the nanometer, is the width of three atoms. Ten nanometers is 1,000 times smaller than the diameter of a strand of human hair. 

The implications of being able to manufacture molecules are staggering. We could replicate any kind of material, from metal and wood to food and DNA. And if you listen to some of the scientists leading the charge, it's not a dream; in fact, they say the mastery of nanotechnology is only a question of when, not if. "The controversial position is that it isn't [going to happen]," says Chris Peterson, executive director of the Foresight Institute, a nonprofit educational organization focused on nanotechnology. 

So, what is nanotechnology exactly? Who's working on it? And why are some people scared by the very thought of it?

Building the Right Tools
The key lies in creating the perfect assembler.

The Face of the Future
The miraculous benefits.

The Dark Side of Nanotechnology
The potential side effects.

Preparing for the Future
How we're rising to the challenge.

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