The August 2001 issue of Scientific American has an interesting article ("Go Forth and Replicate", by M. Sipper and J. A. Reggia) on machine replication. (Unfortunately, it is not available online). The article describes attempts to develop a general understanding of self-replicating systems, with its roots in the work of John von Neumann, Stanislaw Ulam, and others. The article covers research into cellular automata simulations before moving on to describe more recent work by the authors and others that often employ evolutionary methods, including self-replicating systems that do not include an explicit self-description. They also mention the pioneering 1980 NASA study on complex replicating machine systems led by Robert A. Freitas Jr., now a researcher at Zyvex Corp. and author of Nanomedicine.
The authors, aware of the implications, state: "Researchers in the field of nanotechnology have long proposed that self-replication will be crucial to manufacturing molecular-scale machines . . . Recent advances have given credence to these futuristic-sounding ideas." They add that the study of such systems presents a "twofold challenge of creating replicating machines and avoiding dystopian predictions of devices running amok. The knowledge we gain will help us separate good technologies from destructive ones."
Read more for links to a few items related to nanotechnology and self-replicating systems. A primer on Self replication and nanotechnology by Ralph Merkle is available on the Zyvex website.
Some specific papers:
– J. Storrs Hall (2000). Self-Replication and Pathways to Molecular Nanotechnology
– George D. Skidmore, et al. (2000). Exponential Assembly. Additional information available on the Zyvex website.
– J. Storrs Hall (1998). Architectural Considerations for Self-replicating Manufacturing Systems.
– Ralph C. Merkle (1992). Self Replicating Systems and Molecular Manufacturing.