Here are three different ways gray goo might kill you, in ascending order of probability:

3. Tiny nanobots swarm over and disassemble your body, atom by atom. Chances of this occurring? Probably less than being struck by an asteroid.

2. Public worries over gray goo lead to a ban on the development of molecular manufacturing, allowing nations with fewer scruples to develop and make use of the technology — eventually selling ultra-lethal weapons capability to transnational terrorist organizations, who attack without warning.

1. Authoritative U.S. scientists and nano policy makers persist in their ridicule of gray goo scenarios and their dismissal of nanobots as “impossible.” As a result, no policies dealing with the consequences of molecular manufacturing are debated and no attempt is made to cooperate on an international level with other potential developers of the technology. When, a few years later, it is discovered that a heretofore secret program in a non-aligned nation may be on the verge of a breakthrough, other major powers decide to jumpstart their own programs. Before long, several countries find themselves involved in a new, highly unstable, upwardly spiraling arms race. The next war — truly the war that does end all wars — ends your life, and billions of others. Chances of this occurring? Probably high, if present trends continue.