Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!cs.utexas.edu!bcm!dimacs.rutgers.edu!aramis.rutgers.edu!athos.rutgers.edu!nanotech From: landman@eng.sun.com (Howard A. Landman) Newsgroups: sci.nanotech Subject: Re: Is this stuff for real? Keywords: reality nanotech questions Message-ID: Date: 24 Mar 91 23:57:44 GMT Sender: nanotech@athos.rutgers.edu Organization: Sun Microsystems, Mt. View, Ca. Lines: 55 Approved: nanotech@aramis.rutgers.edu In article cphoenix@csli.stanford.edu (Chris Phoenix) writes: >Picture the following nanomachine, designed to prevent mutation: I don't think anyone can have any serious argument with the notion that it is physically possible to design machines which can build useful items but have no chance of reproducing themselves. Your average high-school wood shop, if you imagine it being run by a computer, is as good an example as any. QED. However, people seem to be assuming that this completely settles the question. I don't think so. It doesn't address the "argument from practicality". Consider: we know how to build computers which are pretty much impervious to attacks by viruses. Yet not only don't we do so, we often don't even build systems that make use of the built-in protection available in their own microprocessors (e.g., in the Macintosh OS, every program is run in privileged mode). Why? Because it's "faster" or "cheaper". So (for the sake of argument) I claim that when people first start doing nanotech it will be hard enough just to get the damn stuff to work at all, and few if any will be concerned about making absolutely sure that nothing can go wrong. Some of the design problems will be so hard that we will use evolution (the physical equivalent of "genetic algorithms") to solve them. If you don't believe this, consider that there are already people developing artificial antibodies this way. And some of the methods for creating large systems via tiny operators might more profitably make use of reproduction and morphogenesis based on simple local rules, than of global direction by a Master Control Program with all the massive communication and coordination that implies. In the first case (evolution as a design technique), you can't (by definition) turn off evolution. In the second, since the end product is based on a few simple rules (which it is cheaper NOT to place under strict error correction control), a mutation in the rules could lead to a VERY different end product, which has some potential for altering the reproductive viability of the replicators. None of these things are very likely to create a problem. But as nanotech spreads, it will be used more and more often, by a broader variety of people in a more motley collection of settings, and the cumulative probability of SOME disaster happening SOMEWHERE will eventually approach unity. Note that it is wholly inadequate to counterargue that we "can" do this or that to prevent problems. You must argue that people "will" do this or that, even under pressures of schedule, budget, politics, war, etc. This is a much harder argument and I haven't seen anyone attempt it yet. -- Howard A. Landman landman@eng.sun.com -or- sun!landman