Re: SciAm: nano and cryonics

Date: Fri Aug 24 2001 - 17:07:10 MDT

I received the September issue of Scientific American today. This is
the special issue on nanotech, with some of the articles available
online at

Here are some excerpts from the article by Richard Smalley. Smalley is
a Nobel prize winning chemist (discoverer of buckminsterfullerene) and
nanotech researcher. The article does not really have anything new for
those who are familiar with Smalley's criticisms of nanotech.


   Of Chemistry, Love and Nanobots
   by Richard E. Smalley

   How soon will we see the nanometer-scale robots envisaged by K. Eric
   Drexler and other molecular nanotechnologists? The simple answer
   is never.


   In recent years, it has become popular to imagine tiny robots
   (sometimes called assemblers) that can manipulate and build things
   atom by atom. Imagine a single assembler: working furiously, this
   hypothetical nanorobot would make many new bonds as it went about
   its assigned task, placing perhaps up to a billion new atoms in the
   desired structure every second.


   But how realistic is this notion of a self-replicating nanobot?
   Let's think about it. Atoms are tiny and move in a defined and
   circumscribed way - a chemist would say that they move so as to
   minimize the free energy of their local surroundings. The electronic
   "glue" that sticks them to one another is not local to each bond but
   rather is sensitive to the exact position and identity of all the
   atoms in the near vicinity. So when the nanomanipulator arm of our
   nanobot picks up an atom and goes to insert it in the desired place,
   it has a fundamental problem. It also has to somehow control not only
   this new atom but all the existing atoms in the region. No problem,
   you say: our nanobot will have an additional manipulator arm for each
   one of these atoms. Then it would have complete control of all the
   goings-on that occur at the reaction site.

   But remember, this region where the chemistry is to be controlled
   by the nanobot is very, very small - about one nanometer on a side.
   That constraint leads to at least two basic difficulties. I call
   one the fat fingers problem and the other the sticky fingers problem.
   Because the fingers of a manipulator arm must themselves be made out
   of atoms, they have a certain irreducible size. There just isn't
   enough room in the nanometer-size reactive region to accomodate
   all the fingers of all the manipulators necessary to have complete
   control of the chemistry. In a famous 1959 talk that has inspired
   nanotechnologists everywhere, Nobel physicist Richard Feynman memorably
   noted, "There's plenty of room at the bottom." But there's not *that*
   much room.

   Manipulator fingers on the hypothetical self-replicating nanobot
   are not only too fat; they are also too sticky: the atoms of the
   manipulator hands will adhere to the atom that is being moved. So it
   will often be impossible to release this miniscule building block in
   precisely the right spot.

   Both these problems are fundamental, and neither can be avoided.
   Self-replicating, mechanical nanobots are simply not possible in
   our world. To put every atom in its place - the vision articulated
   by some nanotechnologists - would require magic fingers. Such a
   nanobot will never become more than a futurist's daydream.

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