Viewpoint: Yes, from unforeseen pollution to deliberately designed weapons of mass destruction, nanotechnology holds significant risks, and the legal, technical, and cultural work that must be done to tip the balance toward safety is not being conducted.

Viewpoint: No, nanotechnology research contributions to advanced electronics and medical progress far outweigh any perceived danger.

Everything we see around us is made of atoms, often combined together in molecules of particular chemical compounds. For example, a molecule of water consists of two hydrogen atoms and an oxygen atom. When we deal with materials in our ordinary lives, we handle many billions of molecules at a time. This limits the precision and versatility with which we can manipulate the matter around us.

Nanotechnology is a word used to describe...