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From: carlc@tektronix.UUCP (Carl Clawson)
Newsgroups: net.physics
Subject: Re: Re: Non-linear systems.
Message-ID: <4781@tektronix.UUCP>
Date: Tue, 15-Jan-85 11:31:58 EST
Article-I.D.: tektroni.4781
Posted: Tue Jan 15 11:31:58 1985
Date-Received: Thu, 17-Jan-85 04:19:50 EST
References: <209@talcott.UUCP> <328@rlgvax.UUCP> <384@hou2g.UUCP> <1027@sunybcs.UUCP> <386@hou2g.UUCP>
Reply-To: carlc@tektronix.UUCP (Carl Clawson)
Organization: Tektronix, Beaverton OR
Lines: 21
Summary: 

In article <386@hou2g.UUCP> stekas@hou2g.UUCP (J.STEKAS) writes:
>Randomness and predictability are two different things.  Randomness
>is sufficient for unpredictability but not the only source.
>
>In linear types of systems, like Newtonian orbital mechanics,
>one can easily show that intitial states which are infinitesimally
>different at t=0 will be infinitesimally different at t=T.

Sorry, but Newtonian mechanics is not necessarily linear. (I'm
assuming you're referring to the equation of motion F=ma.)
For Newtonian gravity F is proportional to 1/(r**2), thus
the non-linear equation
           
        2    2                  2
       d r/dt  = constant x 1/(r )
          
Linearity is not necessary for "predictability" as described in the
referenced article.

Carl Clawson
...tektronix!carlc