Gray Goo

In 1986, engineer Eric Drexler raised fears of a nanotechnological insurrection against the human race. While he detailed the many potential benefits of nanotechnology, such as destroying cancer cells and repairing DNA, he also expressed concerns that molecule-sized, self-replicating robots could begin to out-compete natural plants and microorganisms, taking over every ecological niche and eventually consuming all of Earth’s resources: the so-called “gray goo” scenario, also known as “global ecophagy.”

Concern over the predictions led to Prey by Michael Crichton and an agitated Prince Charles convening a “nanotech summit” at his country estate in Gloucestershire. Nanotechnologists such as Richard Smalley responded by saying that the “molecular manufacturing” needed to create these nanobots was scientifically impossible. In order to manipulate atoms (which are sensitive to the electronic bonds of surrounding atoms), molecular assemblers would need additional manipulator “fingers,” but there wouldn’t be enough room at the atomic level. This is known as the “fat fingers” problem. There is also the “sticker fingers” problem: The atoms being moved around by the manipulators would get stuck to them with no feasible way to unstick them. Drexler responded by saying that Smalley’s incredulous attitude toward molecular manipulators came down to a desire to reduce public fears and protect funding for nanotechnology research.

One solution to the threat of gray goo is another form of nanotechnology that would perform a beneficial role: blue goo. These would be self-replicating police nanobots designed as a defense against autonomous and misbehaving gray goo. However, they would also need to be omnipresent, strong, robust, resistant to the gray goo’s effects, and completely under human control. If the blue goo was subverted or overpowered by the gray goo, however, it could very well end up turning against us as well.

Other potential limits on the spread of gray goo include limited replication capacity, wide dispersal, energy and chemical element requirements, or the use of rare elements such as titanium or diamond in constructing molecular assemblers. As the human body contains very little of these rare elements, the goo wouldn’t likely turn on us, although they may eat our smartphones. If these fail-safes didn’t work, however, the end result could be a post-human, post-ecological world of (potentially competing) nanobot swarms.