Our Living Language  : Nanotechnology is the science and technology of precisely manipulating the structure of matter at the molecular level. The term nanotechnology embraces many different fields and specialties, including engineering, chemistry, electronics, and medicine, among others, but all are concerned with bringing existing technologies down to a very small scale, measured in nanometers A nanometer—a billionth of a meter—is about the size of six carbon atoms in a row. (The prefix nano- comes from the Greek word nanos, which meant "little old man" or "dwarf.") Today, as in the past, most industrial products are created by pushing piles of millions of atoms together—by mixing, grinding, heating—a very imprecise process. However, scientists can now pick up individual atoms to assemble them into simple structures or cause specific chemical reactions. Propellers have been attached to molecular motors, and electricity has been conducted through nanowires. Nanotubes made of carbon are being investigated for a variety of industrial and research purposes. In the future, nanotechnology may be able to harness the forces that operate at the scale of the nanometer, such as the van der Waals force, as well as changes in the quantum states of particles, for new engineering purposes. The development of nanotechnology holds out great promise of improvements in the quality of life, including new treatments for disease and greater efficiency in computer data storage and processing. For example, tiny autonomous robots, or nanobots, may one day be sent into human bodies to repair cells and cure cancers, perhaps even extending the human life span by many years. The simple devices created by nanotechnology so far have not yet approached the complexity of the envisioned nanomachines and nanobots. Some scientists even see a dark side to the technology, emphasizing the need for caution in its development, particularly in attempts to create nanobots that can replicate themselves like living organisms.