home *** CD-ROM | disk | FTP | other *** search
- Newsgroups: sci.physics
- Path: sparky!uunet!zaphod.mps.ohio-state.edu!mips!darwin.sura.net!uvaarpa!murdoch!kelvin.seas.Virginia.EDU!crb7q
- From: crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass)
- Subject: Re: Chaos
- Message-ID: <1992Jul23.185339.9436@murdoch.acc.Virginia.EDU>
- Sender: usenet@murdoch.acc.Virginia.EDU
- Organization: University of Virginia
- References: <1076@kepler1.rentec.com> <1992Jul20.153122.29180@murdoch.acc.Virginia.EDU> <76441@ut-emx.uucp>
- Date: Thu, 23 Jul 1992 18:53:39 GMT
- Lines: 56
-
- In article <76441@ut-emx.uucp> johncobb@ut-emx.cc.utexas.edu (John W. Cobb) writes:
- >In article <1992Jul20.153122.29180@murdoch.acc.Virginia.EDU>,
- >crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass) writes:
-
- >|> This is good, if you take credit for 'chaos theory' for all of the
- >|> work going back to Poincare, then you are left with a dilemma. Either
- >|> the subject is a rather evolutionary outgrowth of dynamical systems
- >|> theory with the addition of large computers to guide us, in which
- >|> case it seems difficult to justify assigning earthshattering importance
- >|> to it, or it is not, in which case it seems difficult to justify
- >|> taking credit for 90 year old results.
- >
- >I think this point is fallacious. It is like saying that the discovery of the
- >double helix structure of DNA is an "evolutionary outgrowth" of x-ray
- >crystallography and has no "earthsattering importance". Even Newton admitted
- >that if he had voiced some deep and fundamental ideas that he owed a
- >debt of gratitude to the giants on whose shoulders he stood. The recent
- >flurry of interest in chaos is indeed based upon a long history of previous
- >results of great importance, but it is untrue to somehow imply that very
- >little of the current work is fundamentally new -- it is.
-
- I did not say this. I said that the importance was somewhat overstated
- and oversold. I still say this.
-
- I also implied that certain proponents seem to have blinders that
- seem to shield the importance of most work done before about
- 1975.
-
- [stuff deleted]
-
- >Geometry. That this is an needed task is borne out by many of the comments
- >on this newsgroup that reveal both a fundamental misperception about what
- >chaos means and a refusal to acknowledge that it fundamentally changes
- >notions about dynamics in physical systems where it exists (for example,
- >sensitive dependance on initial conditions implies abscence of predictability).
-
- However, this, as well contains a misconception. Sensitive dependence
- on initial conditions does not necessarily imply unpredictability of
- all gauges of a system, just the one to which the system is sensitive.
- (for example the velocities of a fluid system may be completely
- unstable while the total energy shows a nice smooth bounded behavior.
- If appropriate or possible, one might be better off reformulating the
- system in terms of total energy and leaving the sensitive dependence
- in the dustbin.)
-
- dale bass
-
- >john w. cobb
- >jwc@fusion.ph.utexas.edu
-
-
- --
- C. R. Bass crb7q@virginia.edu
- Department of Mechanical and Aerospace Engineering
- University of Virginia
- Charlottesville, Virginia (804) 924-7926
-