Essays on Infinite Lifespans
Robert A. Freitas Jr.
or (if run backwards) as a motor to convert neon gas pressure
into rotary power. The researchers reported that prelimi-
nary molecular dynamics simulations of the device showed
that it could indeed function as a pump, although structural
deformations of the rotor can cause instabilities at low and
high rotational frequencies. The motor was not particularly
energy efficient but it worked.
The ultimate goal of molecular nanotechnology is to
develop a manufacturing technology able to inexpensively
manufacture most arrangements of atoms that can be speci-
fied in molecular detail. Building medical nanorobots, each
made of millions or billions of atoms, cheaply enough to be
practical for medical therapies requires a new kind of manu-
facturing technology. Molecular manufacturing will be the
ultimate mechanized production in terms of its precision and
flexibility. Two central mechanisms have been proposed to
achieve these goals at the molecular scale: (1) programmable
positional assembly including, for example, fabrication of dia-
mond structures, using molecular feedstock, and (2) massive
parallelism of all fabrication and assembly processes.
As machine structures become more complex, getting all the
parts to spontaneously self-assemble in the right sequence is
increasingly difficult. To build complex structures, it makes
more sense to design a mechanism that can assemble a molec-
ular structure by what is called positional assembly that is,
picking and placing molecular parts. A device capable of posi-
tional assembly at the molecular scale would work much like
the robot arms that manufacture cars on automobile assembly
lines in Detroit, or which insert electronic components onto
computer circuit boards with blinding speed in Silicon Valley.
Using the positional assembly approach, the robot manipula-
tor picks up a part, moves it to the workpiece, and installs it.
The robot then repeats the procedure over and over with many
different parts until the final product is fully assembled.