Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 12/21/84; site seismo.UUCP Path: utzoo!watmath!clyde!cbosgd!ihnp4!zehntel!hplabs!hao!seismo!rivers From: rivers@seismo.UUCP (Wilmer Rivers) Newsgroups: net.physics Subject: Re: Re: Non-linear systems. Message-ID: <14@seismo.UUCP> Date: Fri, 11-Jan-85 17:39:07 EST Article-I.D.: seismo.14 Posted: Fri Jan 11 17:39:07 1985 Date-Received: Mon, 14-Jan-85 01:10:38 EST References: <209@talcott.UUCP>, <328@rlgvax.UUCP> <384@hou2g.UUCP> <1027@sunybcs.UUCP> Organization: Center for Seismic Studies, Arlington, VA Lines: 28 In article <1027@sunybcs.UUCP>, rosen@sunybcs.UUCP (Jay Rosenberg) writes: > Once you accept randomness as the underlining mechanism, there is no > longer a drive to study it. I don't buy that. After all, there are many reasons for studying a system other than being able to predict exactly its future (or past) behavior. Just because a system must be regarded as being stochastic rather than deterministic doesn't mean that you have no interest in determining the structure of that randomness - if you have a black box which is spewing out random numbers, the first thing you would like to do is determine whether those random numbers have a uniform, gaussian, chi-squared, etc., distribution. An extraordinary amount of effort is expended on the analysis of random phenomena such as turbu- lence in fluids or noise in electric and mechanical systems. Ultimately, the knowledge gained in these investigations cannot be used to predict future behavior exactly, but it can be used to express that behavior probabilistically. There is thus considerable motivation for studying phenomena which one regards as being random; in fact, one might even take the opposite viewpoint of regarding the study of deterministic phenomena as being somehow less exciting, because all possible answers that you might work out for the system's future behavior are "predestined" by the initial conditions (in the absence of future perturbations.) It would be rather boring to continue to make measurements and plot points on a graph, knowing that they would all continue to fall on a parabola. Stochastic systems are at least fun to observe precisely because you don't know exactly what's going to happen next. (If you don't believe that, ask the inventor of the "lava lamp" how much he's made from that little gizmo.)