Yet there remains a great deal of confusion about just what nanotechnology is, both among the ordinary people whose lives will be changed by the new science, and among the policymakers who wittingly or unwittingly will help steer its course. Unsurprisingly, some of the confusion is actually caused by the increased attention—sensationalistic reporting and creative license have done little to prepare society for the hard decisions that the development of nanotechnology will make necessary.

Much of the confusion, however, comes from the scientists and engineers themselves, because they apply the name “nanotechnology” to two different things—that is, to two distinct but related fields of research, one with the potential to improve today’s world, the other with the potential to utterly remake or even destroy it. The meaning that nanotechnology holds for our future depends on which definition of the word “nanotechnology” pans out. Thus any understanding of the implications of nanotechnology must begin by sorting out its history and its strange dual meaning.