Eugene pointed out something in his most recent message something
that I hadn't thought much about previously which was harmonic
interference between assembler arms operating simultaneously.
I think it is useful to note that it should be possible to isolate
the arms from one another using acoustical shielding techniques.
I believe in buildings for example they may put layers of
lead sheeting between floors to provide such isolation. You
could imagine diamondoid assembler arms sitting on diamondoid
islands embedded in lead seas. There are probably other methods
as well for disrupting the transmission of any local vibrations
to remote locations such as layers of materials with different
acoustic transmission velocities.
I suspect it may also be possible to have "active" cancellation
technologies just as we now have noise-suppressing headsets
that cancel out background noise such as that found on airplanes.
Finally since the assembler arms are "programmable" you can program
their operational timing so any oscillations they might generate
will tend to cancel each other out rather than interfere with each other.
Since as Josh pointed out [1], the mass self-replication time for
a properly designed assembly line could be as small as 1 millisecond,
you have lots of design room in which to play (assembler spacings,
timings, etc.) to avoid this problem without seriously impacting
being able to assemble useful stuff before hell freezes over.
Eugene's point is useful to consider but I don't think it is a
showstopper.
Robert
1. J. S. Hall, ``Architectural considerations for self-replicating
manufacturing systems,'' Nanotechnology 10, pp. 323-330, 1999. See:
http://www.foresight.org/Conferences/MNT6/Abstracts/Hall/index.html.
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