Path: utzoo!attcan!uunet!jarthur!bridge2!mips!zaphod.mps.ohio-state.edu!samsung!cs.utexas.edu!rutgers!aramis.rutgers.edu!athos.rutgers.edu!nanotech From: well!dduke@lll-crg.llnl.gov (David Allen Duke) Newsgroups: sci.nanotech Subject: SPECULATION AND QUESTIONS Keywords: gate operations, virus, mental state Message-ID: Date: 8 Feb 90 01:31:54 GMT Sender: nanotech@athos.rutgers.edu Lines: 72 Approved: nanotech@aramis.rutgers.edu I have been reading about nanotech in _Foresight Update_ in _EOC_, and a few other places. Maybe someone can answer (or tell me no answer exists to) the following questions: 1. Drexler makes the assemblers sound like a miniature robot with an arm to which is attached a molecule or an atom to be placed at a specific point. The mechanism proposed is "selective stickiness", but this does'nt sound any more usefull than chemistry. Is it? [I'll break my usual rule and answer these questions in-line: Atoms can be "stuck" with forces ranging from covalent bonds to van der Waals forces, with a difference in strength on the order of 100. The most desirable method would seem to be to "pick up" the reagent molecule with a van der Waals bond and have it have it latch onto the object you're building by a covalent bond, allowing you simply to pull the arm away and break the vdW bond by force. Alternatively, you might alter the geometry of the "gripper" to expel the reagent. Chemistry is like building a gadget of Lego blocks by alternately pouring piles of the various different kinds of blocks over the object. The trouble is they will stick everywhere it is possible for them to stick. Nanotechnology (like protein synthesis in the cell) is supposed to be a way to control which of the possible sites, a reaction actually happens at.] 2. Recent articles in _Foresight Update_ speculate about incredibly powerfull computer systems possible in an advanced nanotech society. I guess these speculations are based on the size and speed of imagined mechanical/molecular gate operations. Has anybody guessed what the difficulty would be of making mechanical gate ops interconnected, and how these gate ops would be powered? [As a computer architecture person myself, I've looked at it. The connectivity isn't a problem--remember that existing computers are basically planar; if you allow yourself 3 dimensions it's a lot easier. Power is a bit more out of my field, but suggestions tend to run to electrostatic motors of some kind. No one, by the way, seriously expects that nanocomputers will be actually built this way. Drexler holds them up as existence proofs; real nanocomputers will probably use highly involved quantum effects and run at speeds of about 100 terahertz instead of the roughly one megahertz the mechanical design could do.] 3. The closest thing to a nanomachine I've ever heard of is a virus. Has there been any attempt to alter an existing virus for a purpose? [No and yes. An assembler is not like a virus, since the virus requires an outside self-reproducing mechanism to work; to get going in nanotechnology you need to produce the self-reproducing mechanism itself. On the other hand, a virus might be like some specialized end-product of a different and larger nanotechnological base. And yes, retroviruses have been used to insert missing genes into organisms (I think, including humans).] In regards to discussions about cryonics on this newsgroup: In a technology advanced enough to literally raise you from the dead (frozen), I think the new limitation imposed on that society would simply be raw material. What will the motivation be for that future society to recover you? What will you offer? Should you sign an agreement before you die stating that you will abide by the laws of that future society? One final statement. If the promise of nanotech/AI becomes even partially true then it might be possible to subtly, yet directly alter mental state by altering synaptic wieghts and other aspects of brain function. I will wait for your responses before continuing.