[7] Drexler describes gray goo in Chapter 11 of Engines of Creation: Early assembler-based replicators could beat the most advanced modern organisms.
Tough, omnivorous 'bacteria' could out-compete real bacteria: they could spread like blowing pollen, replicate swiftly, and reduce the biosphere to dust in a matter of days.
We have trouble enough controlling viruses and fruit flies.Drexler notes that the geometric growth made possible by self-replication is inherently limited by the availability of suitable raw materials.
In direct response to Joy's concerns, the first quantitative technical analysis of the ecophagy scenario was published in 2000 by nanomedicine pioneer Robert Freitas.
King Charles III (then Prince of Wales) called upon the British Royal Society to investigate the "enormous environmental and social risks" of nanotechnology in a planned report, leading to much media commentary on gray goo.
The Royal Society's report on nanoscience was released on 29 July 2004, and declared the possibility of self-replicating machines to lie too far in the future to be of concern to regulators.
[9] More recent analysis in the paper titled Safe Exponential Manufacturing from the Institute of Physics (co-written by Chris Phoenix, Director of Research of the Center for Responsible Nanotechnology, and Eric Drexler), shows that the danger of gray goo is far less likely than originally thought.