Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!husc6!rutgers!clyde!cbosgd!ihnp4!ptsfa!lll-tis!elxsi!beatnix!merkle From: merkle@beatnix.UUCP (Ralph Merkle) Newsgroups: sci.misc Subject: Re: Engines of Creation: Nanotechnology Message-ID: <636@elxsi.UUCP> Date: Sat, 5-Dec-87 17:04:40 EST Article-I.D.: elxsi.636 Posted: Sat Dec 5 17:04:40 1987 Date-Received: Fri, 11-Dec-87 07:17:54 EST References: <799@sbcs.sunysb.edu> <2698@drivax.UUCP> <1063@sugar.UUCP> <2411@watcgl.waterloo.edu> <1445@m-net.UUCP> Sender: nobody@elxsi.UUCP Reply-To: merkle@beatnix.UUCP (Ralph Merkle) Organization: ELXSI Super Computers, San Jose Lines: 49 Keywords: nanotechnology foresight drexler >In <2411@watcgl.waterloo.edu> kdmoen@watcgl.waterloo.edu (Doug Moen) writes: >>peter@sugar.UUCP (Peter da Silva) writes: >>>Even Drexler is uneasy about the "Grey Goo". >You have to find it first. The difficulty is that, in order to decide >if a particular bit of nanomachinery is Gray Goo (or a part thereof), >you have to analyze its program to see if it ever quits reproducing. >This is exactly equivalent to the halting problem, which is insoluble. >Russ Cage, Robust Software Inc. (313) 662-4147 {sw1a7,umix}!m-net!rsi Nope. Just destroy anything that is not identifiable as 'friend'. That's the principal the immune system uses, and it seems to work okay most of the time. I should mention that Drexler has proposed more detailed designs of nano computers than the popularizations in EOC. The more detailed designs look quite plausible and look like variations on Babbage's Analytical Engine -- only with smaller gears, levers, etc. The key trick in simplifying the design problem is to (1) propose a few intuitively plausible building blocks -- rods that can be slid back and forth, knobs that stick out of the rods, etc. Then (2) propose a specific chemical structure for each building block, and demonstrate that -- within reasonable engineering tolerances -- it can be treated like the intuitively simple building block (example -- a 'rod' can be made out of a series of carbon atoms, alternately single and triple bonded). Finally (3) put the basic building blocks together into some interesting structure -- such as a computer. The major limitation today is the manufacturing technology. Given an atomic machine shop even I could start making interesting nano-machines using the 'building block' approach. Current molecular-scale fabrication technology is limited to the construction of arbitrary sequences of amino acids (protein engineering). Understanding how to build a protein is rather difficult right now, though a great deal of funding is being poured into research in this area. Building a working machine composed of hundreds or thousands of proteins is beyond current design technology -- though NOT current MANUFACTURING technology. If someone (God, ET's or whoever) gave us the specific amino acid sequences of the needed proteins, we could easily (this is the scientists 'easily', not the engineers 'easily') produce the proper proteins in the proper amounts. Assembly of the proteins is simple: stir them together and watch them self-assemble. This is a standard assembly technique used in existing protein-based machines (us!). Now it's just a small matter of programming :-) to build a molecular level machine shop from proteins. Ralph C. Merkle ...!sun!elxsi!merkle