Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!aramis.rutgers.edu!caen.engin.umich.edu!offutt From: offutt@CAEN.ENGIN.UMICH.EDU (daniel m offutt) Newsgroups: sci.nanotech Subject: Re: Is active shield design intractable? Summary: Yes: on a time scale of decades. Keywords: active shields, cultural evolution Message-ID: <8906130723.AA21670@athos.rutgers.edu> Date: 10 Jun 89 15:46:00 GMT References: <8905310354.AA19565@athos.rutgers.edu> <8906010521.AA05561@athos.rutgers.edu> Sender: nanotech@aramis.rutgers.edu Organization: The University of Michigan Lines: 97 Approved: nanotech@aramis.rutgers.edu In article <8906010521.AA05561@athos.rutgers.edu> offutt@CAEN.ENGIN.UMICH.EDU (daniel m offutt) writes: > >[ various arguments against the claim that active shields can be developed > soon enough. ] > >[The same arguments could be brought against the possibility of > building gray goo in the first place. This is one reason to hope > that the two might occur with some parity of capabilities... > --JoSH] There is clear asymmetry between the difficulty of destruction and the difficulty of maintaining a complex integrated system such as a building, workstation, standard of living, or human body. To destroy is relatively easy, to protect against destruction is much more difficult. To design, construct and maintain a building requires a wide variety of specialized expertise and equipment, applied continuously from the time the building is designed to the time it wears out. But a building can be destroyed in minutes with simple explosives that the Chinese knew how to make more than a thousand years ago. You could destroy the workstation you are reading this message on in less than 60 seconds. But to fix a small problem with the workstation, much less maintain it in good working order for several years, is a much more difficult task requiring special knowledge and equipment. Maintaining the American standard of living is a complex problem demanding millions of specialized forms of knowledge and other capital. But destroying the American standard of living could be done much more easily. A few dozen nuclear explosions would do it. The erection of trade barriers around the US would do it. How does the AIDS virus compare in complexity with the minds of all the thousands of people who have been looking for a cure for the last ten years? Do they have cure for AIDS yet? No. How long have researchers been looking for a cure for the common cold? Do they have a cure yet? No. The human body can be destroyed by the disruption of just *one* life-critical process. There are numerous simple elements, chemicals, viruses, and bacteria that can kill. Killers can be simple. But an active shield (such as the human immune system) is necessarily much, much more complex. So designing killers should be easy compared to designing a broad defensive system. One reason the immune system (and artificial active shields) must be more complex is that the assaults it must defend against are largely unknown. Killers can be simple and compact, so a wide variety can be generated and pitted by Nature against the human immune system at low cost in time, energy and other resources. (Recall that bacteria are rapidly developing resistance to antibiotics. Recall how recently the Plague occurred, and how recently AIDS has arisen.) This means that the immune system is always running into novel assaults. And that means that the immune system faces substantial uncertainty about what assaults it will encounter in the future. On the other hand, the human body is relatively constant -- over the same time scale. That means that processes designing attacks on the human body face substantially less uncertainty. Uncertainty of the mode of attack implies a need for a diversity of defenses, and greater diversity implies greater complexity. This is why viruses and bacteria are so simple relative to the human immune system. If the immune system must be complex in order to cope with uncertainty of mode of assault, then artificial active shields will also have to be complex in order to cope with similar uncertainty. The human immune system is the product of hundreds of millions of years of evolution, including a like amount of time of rigorous testing against the most noxious assaults Nature has been able to devise against it. The immune system reflects, in some never-to-be-fully-understood way, a long history of mostly unknown assaults by viruses and bacteria. Clearly there are not millions of years available to evolve active shields capable of defending against gray goo. Mr. Drexler and others seem to think that cultural evolution on a time scale of decades or centuries is at least as powerful (in the sense of ability to discover solutions to problems -- such as artificial active shield design) as biological evolution is on a time scale of hundreds of millions of years. I believe this assumption is dead wrong. It needs to be considered very much more carefully by nanotechnologists. Dan Offutt offutt@caen.engin.umich.edu [Very cogently argued. The only hope I can see is that the argument may perhaps be reversed. A self-reproducing gray goo is itself a complex mechanism, of necessity. Thus countermeasures, like antiseptic swabbed on a wound, can occupy the simple, destructive role in your scenario. This only works, of course, if there is an active intelligence recognizing threats and orchestrating the application of the destructive agent. This would mean that a gray could be fought, but also that it must be fought--we could not whip up and rely on some a priori defense. --JoSH]