# Re: Importance of chaos theory

*From*: Ivan Voras <ivoras@xxxxxxxxx>*Date*: Sat, 07 Aug 2010 16:48:39 +0200

On 30.7.2010 17:53, unruh wrote:

On 2010-07-30, Tom St Denis <tm@xxxxxxx> wrote:

I don't know if that's considered "chaotic." In my mind a chaotic

function is one which behaves highly non-linear even with respect to a

great many sample points. Like I can know the temperature for the

last 100 days but I still can't plot out to tomorrow let alone next

week, let alone next month.

Sure you can. The temp may well be chaotic, but that does not stop one

being able to talk about climate. The earth's orbit is chaotic, but that

does not stop us from being able to predict the earth's position next

year (or even 1000 years) with amazing accuracy

I'm not nearly an expert but that is, as far as I understand it, at the

heart of it. A chaotic system implies both non-periodicity in the strict

sense - you don't *ever* get exact repeat of a long enough sequence -

and an "attractor", mostly meaning that, as a pattern-seeking minds, we

clearly see some type of patterns in the data set. It's exactly what

happens with multi-body physics: we "see" planetary orbits and can

approximate planets' positions in the future but we can never calculate

100% exact (down do individual atoms) positions.

I think that this difference between what is approximated and what is

"exact" could be a good source of true randomness but probably not easy,

as the "attractor" part of the whole thing means there can be false

periodicity if measured with insufficient precision (for the planetary

example: if we allow loss of precision we can arrive at completely

predictable orbits, useless for randomness, but on the other hand,

unfortunately, we cannot measure planetary positions to within

atom-sized levels of precision and use that for a source of randomness).

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