The concern about advanced forms of nanotechnology, after feasibility issues have been addressed, tends to center on the possibility of the technology getting out of control. Popular science fiction describes molecular robots that are autonomous self-replicating machines or autonomous replicators that evolve beyond human control, or cant stop reproducing.
For the purpose of our Guidelines, an autonomous replicator is a specific kind of device that both (1) contains a set of materials processing and fabrication mechanisms sufficient to perform the operations necessary build devices like itself and (2) contains a set of design instructions and instruction-interpreting mechanisms sufficient to direct the operations necessary to build a device like itself.
All other machines, lacking these exceptional properties, are not autonomous replicators. Productive nanotechnology enabled manufacturing of small or large products does not require any autonomous replicators, either in development or in application. It is also important to distinguish between the special purpose ability to manufacture many copies of a specific product, and the ability of the manufacturing infrastructure to replicate itself.
Nature employs its own biological form of molecular manufacturing to produce organisms.
Productive nanosystems can be completely non-biological. They can be designed to function in a narrow and controlled range of physical conditions. Autonomous self-replicating assemblers are not necessary to achieve significant manufacturing capabilities.
As Drexler and Phoenix indicated in their Safe Exponential Manufacturing paper (2004 Nanotechnology15 869-872), developing manufacturing systems that use general purpose replicators able to extract their own energy sources is unnecessary.
It is important to note that molecular nanotechnology not specifically developed for manufacturing could be implemented as non autonomous replicating systems that have many layers of security controls and designed-in physical limitations.
This class of system could potentially be used under controlled circumstances for nanomedicine, environmental monitoring, and specialized security applications.
There are good reasons to believe that when designed and operated by responsible organizations with the appropriate quality control, these non autonomous systems could be made arbitrarily safe to operate. However, a determined and sophisticated group of terrorists or "non state entities" could potentially, with considerable difficulty, specifically engineer systems to become autonomous replicators able to proliferate in the natural environment, either as a nuisance, a specifically targeted weapon, or in the worst case, a weapon of mass destruction.
Both conventional nanoscale technology and manufacturing enabled by productive nanosystems can be implemented by responsible parties quite effectively without these risks, but as with other technologies, the risk of abuse must be considered seriously. Thus, in addition to the need for professional ethics and multiple layers of embedded industrial controls, there will also be a need for thoughtful regulation, monitoring, and potentially the development of "immune responses" to external threats.
