Also known as the
grey slime scenario or the Grey Goo End. A worst-case state in
nanotechnology development. The scenario:self-replicating
nanotech 'machines' are created and have the ability to restructure matter at the atomic level. Due to an uncontrolled release or design flaw, the machines restructure all available matter into more
nanotech machines, covering the earth in a grey slime of
nanobots. Similar in concept to
Kurt Vonnegut's chillin'
Ice-9 disaster at the end of
Cat's Cradle but with a hip nanomech twist.
Just so you don't spend a sleepless night worrying, rest assured that available energy constraints and ready supplies of necessary elements would probably keep this from happening. However, some more likely goo scenarios are
On the upside, there might be a defence in the form of blue goo.