From: solovay@math.berkeley.edu (Robert M. Solovay)
Newsgroups: sci.nanotech
Subject: Some questions re "Nanosystems".
Date: 16 Dec 92 05:08:02 GMT


	What follows is a {somewhat edited] transcript of one of the
topics in the WELL conference on Nanosystems I mentioned in a previous
posting. I'd be very curious to hear what people more familiar with
Drexler's book have to say about Hudson's objections. I'll act as a
conduit and post replies in this conference back to the WELL. {I have
not edited individual postings, just deleted some irrelvant postings in
this topic.}


Topic   6:  Nanosystems - New Drexler Book - Critique
By: Hudson Hayes Luce (hluce) on Sun, Nov 15, '92
	13 responses so far



  This topic is for discussion of "Nanosystems: Molecular Machinery,
  Manufacturing, and Computation" by K Eric Drexler, (1992).

13 responses total.


Topic   6:  Nanosystems - New Drexler Book - Critique
#  1: Hudson Hayes Luce (hluce)      Sun, Nov 15, '92  (15:05)      12 lines

  I'd like to start this topic off by listing a few of the things that I found
  to be of interest in Nanosystems. I will try to limit each discrete topic
  to one screenful of text. Of course, it is not possible to show the diagrams
  of molecules that are so necessary to some of the arguments put forth,
  so this discourse must be somewhat limited. I assume some knowledge
  on the part of the participants, and also assume the willingness and
  ability to use a university library if questions of fact or definition arise.
  If some of the points I bring up are out of your respective fields, it
  might be wise to latch on to a graduate student in the appropriate
  discipline (Synthetic Organic Chemistry, for example), and have her
  have a look at "Nanosystems". I will give page numbers for each objection
  raised.


Topic   6:  Nanosystems - New Drexler Book - Critique
#  3: Hudson Hayes Luce (hluce)      Sun, Nov 15, '92  (15:19)      16 lines

  For starters, let's look at p259, figs. 9.2a-e. Drexler terms these
 structures
  "diamondoid" and ascribes the properties of diamond to them. Diamond
  is made up of carbon atoms covalently bonded to each other, and except
  for the surface, all bonds are single bonds. All of the three-atom C-C-C bond
  angles are 109.5 degrees, and all of the C-C-C-C bond dihedral angles are
  + or - 120 degrees. This conformation minimizes strain energy. Moreover,
  all of the rings in the structure are six-membered.
 
  However, in structure 9.2c, there are fused 3- and 4-membered rings, which
  have bond angles of 60 degrees and 90 degrees, respectively, and whose
  C-C-C-C dihedral angles, in some cases, are 0 degrees. This structure is
  highly strained due to bond angle deformation and non-bonded steric
  interactions. Compound 9.2c can thus be assumed to be highly unstable
  at room temperatures, and is probably subject to thermodynamically-
  driven rearrangement.

Topic   6:  Nanosystems - New Drexler Book - Critique
#  4: Hudson Hayes Luce (hluce)      Sun, Nov 15, '92  (15:23)       6 lines

  On p265 Drexler states "acquiring and processing molecules from solution.."
  in reference to a possible use of nanosystems, but on p5 he states that "The
  operating environment assumed for the nanomechanical and mechano-
  synthetic systems discussed in Part II is high vacuum"
 
  Describe a high-vacuum/solvent interface.

Topic   6:  Nanosystems - New Drexler Book - Critique
#  5: Hudson Hayes Luce (hluce)      Sun, Nov 15, '92  (15:34)      19 lines

  On p 196 it is stated, "In solution-phase chemistry, when molecular
 potential
  energy is transformed into mechanical energy, this promptly appears as heat
  Reactions that reduce potential energy are accordingly termed exothermic,
  those that increase it, endothermic. In mechanochemical systems, however,
  potential energy released by a reaction can often be stored elsewhere in the
  mechanical system, either as potential energy or as kinetic energy in the
 form
  of orderly motion"
 
  Potential energy can be transformed into kinetic energy. True.
  Kinetic energy can be stored in the form of orderly motion. True.
 
  Kinetic energy can also be dissipated as heat, as random vibrational,
 rotationl, or translational motion.
 
  Analyse Drexler's statement in light of the 2nd Law of Thermodynamics. If
 this
  statement is true, perpetual motion is possible.