Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!decwrl!apple!bbn.com!archive.bbn.com!aboulang From: aboulang@bbn.com (Albert Boulanger) Newsgroups: comp.ai.philosophy Subject: Re: emergence (and self-organization) Message-ID: Date: 6 Oct 90 00:53:49 GMT References: <3531@media-lab.MEDIA.MIT.EDU> Sender: news@bbn.com Reply-To: aboulanger@bbn.com Organization: BBN, Cambridge MA Lines: 83 In-reply-to: mt@media-lab.MEDIA.MIT.EDU's message of 3 Oct 90 00:40:52 GMT In article <3531@media-lab.MEDIA.MIT.EDU> mt@media-lab.MEDIA.MIT.EDU (Michael Travers) writes: It's interesting to note that some of the better work done on emergent properties comes from the group at Los Alamos that is interested specifically in NON-linear systems, that for one reason or another do not obey the superposition principle. These people (such as Chris Langton, chair of the Artificial Life workshops) are very much NOT asserting that emergent properties are nonphysical or inherently inexplicable. In fact, they rather make a fetish of insisting that complex properties like life or intelligence be modelled bottom-up in terms of simpler processes. Right on! Good to emphasize the NON-linear. I believe that our beginning to tackle the analysis of non-linear systems is a big part of what make the current connectionist movement different from the last cycle and is not just old wine in new bottles. Here are some common ingredients in systems with emergent properties: The system has nonlinear dynamics. The system has something called "frustration". This represents two (or more) processes in competition; the classical example is the frustration of spins in simple models of magnetic domains, called spin glasses. This frustration, via the nonlinearity of the system, acts to amplify novelty, and, by a process of self-organization can create amazing (and robust) structure. This is the basis to solitons. Coming from the empirical side of the tracks, I thought I would share with you two examples of physical systems that is often said to have emergent properties (which is often closely related to self-organization). I think these can serve as useful checks on any discussion of emergent properties of systems. Example 1: Video Feedback. This is something one can do themselves: "Space-Time Dynamics in Video Feedback" James. P. Crutchfield Physica 10D(1984) 229-245 (This is in one of the cellular automata conference books) "Spatio-Temporal Complexity in Nonlinear Image Processing" James P. Crutchfield IEEE Trans Circuits and Systems Vol 35, No 7, July 1988, 770-780 To do this simply point the camera at the TV and zoom in. More interesting behavior can be had with a rotation between the camera and the screen. Play with the color, and contrast settings. Place things like your hands in front of the screen. Example 2: 4-Wave-Mixing with Photorefractive Crystals "Photorefractive Nonlinear Optics" Jack Feinberg Physics Today, October 1988, 46-52 "Optical Systems That Imitate Human Memory" Dana Z. Anderson Computers in Physics March/April 1989 One interesting emergent behavior in these crystals is the self-organizing beams that is caused by the interaction of scattering processes and reflection. Beams will jump out of the crystal and track any reflective object that happens to wander by. Read the first article for a host of other interesting behaviors. Here is a quote from the first article: "When pressed with a working demonstration of these photorefractive circus acts, even hardened physicists, weary from decades of proposal writing, instinctively begin to play with the incident optical beams to see how the crystal will respond. Experimenting with a photorefractive crystal make one feel like a young child examining a caterpillar: If I poke it here, what will it do?" For me, emergent properties of nonlinear systems is an affirmation that there is, indeed, plenty of room at the bottom. Regards, Albert Boulanger aboulanger@bbn.com