Friday, May 13, 2005

Self-replicating MacroBot?


"Humans do it, bacteria do it, even viruses do it," reports Nature. Now, robots can be masters of their reproductive domains. But will Lord Broers believe it? (One thing for sure, I just asked for it.)


Anonymous said...

Why does the phrase "Stupid Robot Tricks" come to mind. The one on the left looks a little worse for wear. Now they need to get the robot that the robot built to build a robot.

attobuoy said...

More important than the stuid robot tricks is the authors' definition of self-replication:


We circumvent the long-standing hurdle of
what counts as self-replication by suggesting
that self-replicability is not a binary property
that a system either possesses or not, but is a
continuum dependent on the amount of
information being copied. This factor can be
measured by comparing the log probability
of a machine spontaneously appearing in an
environment to the log probability of it
appearing, given that one instance already
exists. This factor can be computed precisely
for some well-defined formal systems13 and
approximated for others. For example, an
abstraction of Penrose’s replicating tiles11
yields a factor between zero (not self-replicating)
and log 2.
Even without calculating absolute numbers,
systems can be ranked by comparing
properties that affect this factor, such as the
number of basic building blocks used compared
with the number of building-block
types and their complexity. This factor is
exceedingly high for animals, which have
about 1020 amino-acid combinations of
roughly 20 amino-acid types, but is very low
for our robots (four modules of one complex
type). This view allows us to quantify,
compare and systematically improve the processes
of self-reproduction. It is possible, for
example, that self-reproducing machines
composed of many identical microscale
modules would improve this factor.
Although the machines we have created
are still simple compared with biological systems,
they demonstrate that mechanical selfreproduction
is possible and not unique to
biology. . . .

Anonymous said...

I think the evolutionary concept of 'fitness' is a better quantitative measure of the ability to self-replicate.

In a environment where multiple types of organisms compete for scarce resources, the organism which generates the most progeny (in the long run) is the most fit.