From: cuhes@csv.warwick.ac.uk (Malcolm McMahon)
Newsgroups: sci.nanotech
Subject: Re: Surviving
Date: 25 Jan 93 22:05:40 GMT
Article-I.D.: planchet.Jan.25.17.05.40.1993.10177
Organization: Computing Services, University of Warwick, UK

Ian,
     I  think  each  of us has rather a different  picture  as  to  what 
manufacturing is likely to be like in a nanotech dominated society.  You 
see  manufacturing  and distribution carrying on much the  way  it  does 
now. I see a radical move to decentralisation.

     Consider the use of computers.  About 25 years ago when I wrote  my 
first computer program I had to punch it onto cards and put them into  a 
mainframe.  A few hours later I would go back and collect a listing. Now 
most  of the computing tasks I have I can do at home on my PC and  if  I 
had  one  too big I just have to fire up my  modem.  If  nanotech  based 
factories  appear  I  would expect them only to be  a  brief  transition 
stage  like  card  deck to  lineprinter  computer  facilities.  I  would 
expect,  in  the  longer term,  the overwhealming majority  of  nanotech 
based manufacturing to happen at home.

     Let  me  give you my vision of manufacturing say  a  century  hence 
(though it could be less).

       Browsing  on  a multi-media information network  you  come  on  a 
design  for a new car that you quite like the look of.  You take a  good 
look in virtual reality.  Try it out in a driving simulation.  It  seems 
better  than  the one you have at the moment.  You download  the  design 
into your PC and tell it to go ahead and make it.

     In a machine which could be anywhere convenient on the premises  is 
a  small  cell in which the necessary conditions  of  vacuum,  cold  and 
supplies of feedstocks are maintained or can be generated.  In this cell 
one of a small stock of programmable replicators makes a copy of  itself 
and attaches it to an interface where the car design is downloaded  into 
it.

     The  replicator  then makes a few hundred  copies  of  itself,  say 
eight generations (copying the car program too,  of course).  They  then 
construct the egg shell.  The surface is complex.  It contains molecular 
mills   which   can   selectively   pump   particular   molecules   (see 
"Nanosytems").  It may contain heat pumps (there are a number of designs 
of heat pump that might be suitable,  one of them a semiconductor device 
(The "Peltzier" effect?)).  When it gets bigger it is likely to  develop 
fins  or  spines  to  increase  its  surface  area.   The   nanomachines 
incorporate themselves into the shell. Inside is fuel.

     Under  your back lawn is a large tank containing a witches brew  of 
finely  ground raw materials and fuel.  Aerators are turned on  and  the 
egg is projected down a (fallopian ?) tube into the tank.  The molecular 
mills  in the eggshell start to grind.  The molecules desired  for  this 
particular project flow into the egg.

     Some  of these molecules are used by the nanomachines in the  shell 
to make new sections of shell,  thus the shell grows maintaining  within 
itself  the environment necessary for nanotechnological manufacture  and 
containing an ever increasing population of busy machines.

     Now  you don't want to have to fish your new car out of  the  tank. 
In  any  case it might be bigger than the tank.  So,  when the  egg  has 
enough surface area to give a high enough feed rate it extrudes a  pipe, 
perhaps with an eye on the end,  which finds its way out of the tank and 
onto your drive.  The end bulges out and becomes another shell. This one 
opaque  and the molecular mills on its surface take it only CO2.  It  is 
recognisably car-shaped.

     Inside,  the nanomachines "crystalise", attaching to one another to 
form a kind of scafolding on which the final artifact is made.  Part  of 
this  scafolding  is  a arterial network of  molecular  conveyors  which 
fetch material sent down the pipe.  The machines use this supply firstly 
during  the construction of the scafolding to make more  of  themselves, 
then  to make the structure of the car itself.  As the car is  completed 
the machines canibalise one another and either use the materials in  the 
construction or send them back down the conveyor system which begins  to 
operate in reverse gear.

     Finally  the  shell  is empty except for the  new  car.  The  shell 
itself  now self-destructs in an orderly manner.  First it  develops  an 
inner surface similar to the outer,  becoming a double shell.  The inner 
chamber  is  now  opened to  the  environment,  and  machines  operating 
between  the  two  skins of the shell take  it  apart,  strip  by  strip 
returning  the  materials down the tube and eventually  to  the  storage 
tank.

     Now all this may appear very speculative and I dare say I'm  guilty 
of  designing flying machines with flapping wings.  When I wonder how  a 
particular  thing could be achieved by nanotech I ask myself "how  would 
cells  tackle  it?" This usually shows a way it could  be  done,  though 
probably not the best way.

     This  approach,  by  the way,  gives an immediate  answer  to  your 
questions about how a nanomachine can hear,  or measure  temperature.  A 
bunch  of nanomachines would get together and form a membrane,  maybe  a 
couple  of  millimeters across.  The membrane could be  assembled  as  a 
temporary structure or it could actually consist of nanomachines  docked 
together.  In  either case nanomachines incorporated into the  structure 
could  sense  sound  as variations of strain  on  either  their  docking 
conectors  or  whatever manipulators they were using to hold  on  to  an 
external  membrane.  The  same general technique can be  used  in  every 
situation  where  the  small size of nanomachines  becomes  a  liability 
instead of an asset.

     To answer some specific points I don't think this covers:-
     As  I understand it the term "replicator" means an assembler  which 
can  copy  itself.  Until we get these assemblers  seem  almost  useless 
since  they  can  manufacture  only  one  molecule  at  a  time,  though 
nanomachines would be useful as sensors and so on.

     The  difference  between  a key chemical and  a  special  "vitamin" 
feedstock  seems academic to me.  Nanomachines have to  recognise  their 
feed molecules in any case.

     How to recognise atoms?  As usual, ask nature. Atoms are recognised 
by their chemical binding properties and their steric  properties,  i.e. 
more or less by their size.  However I don't see why a nanomachine can't 
weigh  atoms (or more properly measure their mass) simply  by  attaching 
them  to  an arm an measuring its resonant  frequency,  especially  with 
heavy atoms.

     This  is  not the proper forum to discuss drug politics  at  length 
but  I'm one of the growing number of people who believe that the  drugs 
problem  is caused by the drug laws and will quickly evaporate if  those 
laws are repealed (without killing a lot of people,  or even  increasing 
the  ammount of drug use substantially).  I'd be glad to go into  detail 
by e-mail if you like.

     No,  I  don't pretend to know what type of political  and  economic 
structures will emerge if we survive the development of  nanotechnology. 
I do know,  however,  that no existing economic system will do.  This is 
something I'd like to debate at length here.

      What I'm saying about AI is this.  The origins of human motivation 
are  obscure and complicated.  We are programmed by our genes for  their 
benefit and by our memes for society's benefit.  It seems to me that  an 
important  and neglected area of AI is the question of where an AI  will 
get  its  motivations from.  The assumption seems to me that  they  will 
have  a  copy  of human motivations.  If so,  I think  we'd  be  in  big 
trouble.

Malcolm McMahon