- #1

Vrbic

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Thank you all for response.

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- Thread starter Vrbic
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- #1

Vrbic

- 407

- 18

Thank you all for response.

- #2

DrClaude

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The best for you is to pick up a book on the subject. I suggest https://www.amazon.com/dp/0521010845/?tag=pfamazon01-20*https://www.amazon.com/dp/0521010845/?tag=pfamazon01-20 *or https://www.amazon.com/dp/0198508409/?tag=pfamazon01-20*https://www.amazon.com/dp/0198508409/?tag=pfamazon01-20.*

(Note: I am assuming that when you say your are studying physics and math, it is at the undergraduate level. A more popular science introduction is James Gleick's*Chaos*.)

(Note: I am assuming that when you say your are studying physics and math, it is at the undergraduate level. A more popular science introduction is James Gleick's

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- #3

anorlunda

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- #4

Vrbic

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Ok, I try it. I was also thinking about some video lecture, thank you.The best for you is to pick up a book on the subject. I suggest https://www.amazon.com/dp/0521010845/?tag=pfamazon01-20https://www.amazon.com/dp/0521010845/?tag=pfamazon01-20or https://www.amazon.com/dp/0198508409/?tag=pfamazon01-20https://www.amazon.com/dp/0198508409/?tag=pfamazon01-20.

(Note: I am assuming that when you say your are studying physics and math, it is at the undergraduate level. A more popular science introduction is https://www.amazon.com/dp/0143113453/?tag=pfamazon01-20.)

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- #5

Vrbic

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Does it come this behavior because of we are not capable to solve it analytically? From numerical solution which is not perfect? If I don't count case for small angles when we substitute sin(a) -> a.

Now I realize that something similar arises for three body problem in 3D. Where does it come from? May I compare it to uncertainty in quantum mechanics?

- #6

anorlunda

Staff Emeritus

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Where does it come from? May I compare it to uncertainty in quantum mechanics?

No, not like quantum mechanics.

[PLAIN]https://en.wikipedia.org/wiki/Chaos_theory said:[/PLAIN] [Broken]

Small differences in initial conditions (such as those due to rounding errors in numerical computation) yield widely diverging outcomes for such dynamical systems — a response popularly referred to as the butterfly effect - rendering long-term prediction of their behavior impossible in general.[2][3] This happens even though these systems are deterministic, meaning that their future behavior is fully determined by their initial conditions, with no random elements involved.[4] In other words, the deterministic nature of these systems does not make them predictable.[5][6] This behavior is known asdeterministic chaos, or simplychaos.

Please read the entire Wikipedia article.

I wish more people would spend just a few minutes on Wikipedia for simple questions before posting questions to an online forum. Wikipedia is really a marvelous resource for simple things (but not advanced stuff).

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- #7

sophiecentaur

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Also, Rabbit and Fox population variations - plus many more.

- #8

Khashishi

Science Advisor

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The logistic map is a classic simple example. https://en.wikipedia.org/wiki/Logistic_map

Try setting r = 3.6 exactly, and computing the sequence for x, with two starting values which are very close (let's say, using the smallest difference representable on your calculator) and watch how they diverge.

Most natural systems are chaotic to some degree.

- #9

sophiecentaur

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Chaotic systems can be purely mathematical - remember all the pretty fractal patterns that we used to take hours of CPU time plotting? Those patterns are the result of known discrete input values to the model.Most natural systems are chaotic to some degree.

Natural systems are not like that because the input variable(s) are never known and are actually random (thermal noise being one good reason for that) and the resulting states of the system can look random. It's only after analysis of these states (looking at the underlying patterns) that you can say whether the behaviour is chaotic or not.

As Khashishi says, above, you can't predict exact behaviour in the distant future but, on the other hand, you can often predict the limits of the outcome variables if you use a well informed mathematical chaotic model. We can do better than say "we just don't know". We always blame the weather forecasters but they do tend to get it nearly right for most people for most of the time.

- #10

Khashishi

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- #11

Vrbic

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1) Do you feel as problem that we are not capable predict future results of many systems?

2) Did you ever think that the concept of description of nature is not good (appropriate)? That the mathematics as we know it now has limitation and it may exists other point of view on reality? Or have you ever met with such ideas (from inteligent people)?

I suppose, there are not right answers now, I would like just hear your opinions.

Thank you.

- #12

Khashishi

Science Advisor

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2. No. Mathematics is the best tool for understanding chaos.

- #13

Vrbic

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1) Yes we can, but not good for longer time. Does this discipline develop (chaos theory)? Is possible that after some time the limit will be moved and for example we will predict weather one month to the future (due to developing of theory of chaos)?

2. No. Mathematics is the best tool for understanding chaos.

2) I wrote it a bit roughly. I meant for example that concept of using differential equations is not good enough. That it works very well for some situations but not for other and someone should think about new descriptions of problems (by mathematics).

- #14

DrClaude

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It1) Yes we can, but not good for longer time. Does this discipline develop (chaos theory)? Is possible that after some time the limit will be moved and for example we will predict weather one month to the future (due to developing of theory of chaos)?

It's the other way around: even simple systems that would be described exactly by simple mathematical equations can exhibit chaos. Actual systems that in their simple form are approximately described by the same equations will be even more difficult to predict because you have to add additional uncertainty on top of the chaos.2) I wrote it a bit roughly. I meant for example that concept of using differential equations is not good enough. That it works very well for some situations but not for other and someone should think about new descriptions of problems (by mathematics).

I really recomment you pick up one of the books I mentioned.

- #15

Vrbic

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Ok, I will. And thank you for your suggestions and your opinions.Itmightbe possible that, with progress in measurement and computation, the weather be predicted one month in advance. But what chaos theory tells you is that this will be very hard, and exponentially so. What chaos theory also tells you is that chaotic systems can still have behaviors that are predictable on average. A good example is the difference between weather and climate: I don't know what the weather will be like in six months, but I can tell you that it will be (on average) warmenr than it is now (if you are in the Northern hemisphere).

It's the other way around: even simple systems that would be described exactly by simple mathematical equations can exhibit chaos. Actual systems that in their simple form are approximately described by the same equations will be even more difficult to predict because you have to add additional uncertainty on top of the chaos.

I really recomment you pick up one of the books I mentioned.

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