Self-replication
Any self-replicating mechanism which does not make a perfect copy (mutation) will experience genetic variation and will create variants of itself.
Early research by John von Neumann[2] established that replicators have several parts: Exceptions to this pattern may be possible, although almost all known examples adhere to it.
Four of these can be linked together (through base pairing) in a certain order following a template of four already-linked sequences, by changing the temperature up and down.
No external agent such as an enzyme is needed, but the system must be supplied with a reservoir of the sixteen DNA sequences.
This approach is common in most self-replicating systems, including biological life, and is simpler as it does not require the program to contain a complete description of itself.
A setiset of order n is a set of n shapes that can be assembled in n different ways so as to form larger replicas of themselves.
A NASA study recently placed the complexity of a clanking replicator at approximately that of Intel's Pentium 4 CPU.
Given the currently keen interest in biotechnology and the high levels of funding in that field, attempts to exploit the replicative ability of existing cells are timely, and may easily lead to significant insights and advances.
This, in turn, has given rise to the "grey goo" version of Armageddon, as featured in the science fiction novels Bloom and Prey.
[12] The guidelines recommend that researchers use several specific techniques for preventing mechanical replicators from getting out of control, such as using a broadcast architecture.
Research has occurred in the following areas: The goal of self-replication in space systems is to exploit large amounts of matter with a low launch mass.
For example, an autotrophic self-replicating machine could cover a moon or planet with solar cells, and beam the power to the Earth using microwaves.
Once in place, the same machinery that built itself could also produce raw materials or manufactured objects, including transportation systems to ship the products.
Chlorine is very rare in lunar regolith, and a substantially faster rate of reproduction could be assured by importing modest amounts.
Nanotechnologists in particular believe that their work will likely fail to reach a state of maturity until human beings design a self-replicating assembler of nanometer dimensions.
In the meantime, a Lego-built autonomous robot able to follow a pre-set track and assemble an exact copy of itself, starting from four externally provided components, was demonstrated experimentally in 2003.
[2] Merely exploiting the replicative abilities of existing cells is insufficient, because of limitations in the process of protein biosynthesis (see also the listing for RNA).
In 2011, New York University scientists have developed artificial structures that can self-replicate, a process that has the potential to yield new types of materials.
