The Implications of Self-Replicating Nanobots
Since nano-based molecular manufacturing was first theorised, a concern arose that self-replicating nanobots would get out of control and start reducing the entire planet to copies of themselves, reducing it to "grey goo", which is not necessarily grey or gooey, but refers to a substance that increases exponentially without practical limit. While this scenario would be avoidable with careful planning beforehand, and is unlikely to accidentally occur, eventually it could be developed on purpose, by terrorists or anarchists or others as a type of blackmail. This would result in a nearly unstoppable outbreak causing severe and irreversible damage.
Timmy and the Grey Goo
Picture labelled for reuse by traveladventures.org
Why is it Unlikely to Happen Unexpectedly?
This scenario of unstoppable self-replicating nanobots that grow exponentially is definitely possible, but unlikely to happen accidentally. 'Grey Goo' wouldn't just pop into existence without something first assembling and then programming the nanobots, and self-replicators are too complex and inefficient for practical manufacturing. Nanofactories that build certain products cheaply and quickly are much more suited to the task of molecularly manufacturing products to sell. Even if a use for self-replicating nanobots was found, with some simple programming on what to replicate, how much to replicate and how long to replicate for, the grey goo scenario could easily be avoided. One of the only ways that this could happen would be through a programming malfunction. This is not to say that people uneducated in nanotechnology might release it, or that criminals or terrorists would release it as a form of blackmail.
Why Would it be So Hard to Stop?
If self-replicating nanobots were to go out of control, they would be incredibly difficult to stop. Stopping the nanobots would be simple if the maker manufactured them with a 'kill switch', or something that would stop them remotely. If anyone was foolish enough to create them without a kill switch, then the only way scientists theorise they could be stopped is by using other nanobots to destroy them. This is only a theory however, and may not even work. Even if it did, this would require a lot of effort and money, and would be difficult to implement it in time to stop the epidemic of nanobots. This is why it is so important to stop this outbreak before it can occur.