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Re: [Phys-l] Simulating a disturbance of a stable planetary system.



2) I think it's a matter or resolution. The very * unstable pencil is subject to draughts which are below the threshold of I.P.

IIRC, someone complained that repeating I.P. w/ identical initial condix. gave the same result -- I thought that was always the cae 'till Heisenberg, et al. W/ in the resolution of I.P. a different condition resulted in a vastly different trajectory for a chaotic system. (assuming chaotic parameters and system) [The Cal Poly, not SLO City one]

So I think it's just a matter of incorporating nudges that the I.P. recognizes. No one has volunteered to give me I.P., so I don't know if one can type in values that are below its resolution.

* very => a quickly thought definition: < 0.0001 delta E / E e.g. change in m*g*h for collapse. (The point isn't "infinitely" sharp.) A pencil on its new eraser is sl. stable or sl. unstable, depending on ones personality. For a very sl. "push" the c of g goes "up". More; it goes down and collapse.


1) I think it's already been given, subtly. [JD]


bc requested evaluation copy



Ludwik Kowalski wrote:

On Jan 1, 2008, at 6:14 PM, John Denker wrote:


. . . Secondly, much of the discussion has suffered from
assuming that the system was "stable" according to one
misdefinition, and then assuming that it would behave
as "stable" according to some other misdefinition. This
is not what I would call pedagogically correct. It's not
good pedagogy. It's not good science. It's not even
good scholasticism.


1) What I would like to learn, from messages on this thread, is how to distinguish a stable system from an unstable system. Don't we need a definition of stability (for the kind of systems being discussed)? If so then what is the acceptable definition?

2) This question is practical, not scholastic. The simulation software I am using , I.P., seems to be highly reliable (consistent with underlying physics). How to use such software to account for unavoidable perturbations? The I.P. does not account for them. Please help me with this issue.



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Ludwik Kowalski, a retired physicist
5 Horizon Road, apt. 2702, Fort Lee, NJ, 07024, USA
Also an amateur journalist at http://csam.montclair.edu/~kowalski/cf/

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