Double pendulum, time question

AI Thread Summary
The discussion centers on the double pendulum and whether it can return to its initial configuration after a certain time. It highlights that, due to the chaotic nature of the double pendulum, it generally does not return to the same state, despite Poincaré's recurrence theorem suggesting the possibility. The equations of motion for a double pendulum are typically solved numerically, which can lead to instability over long periods. When displacements are small, the system behaves in a predictable manner, but large displacements result in chaotic motion. Overall, the double pendulum exemplifies how deterministic systems can exhibit unpredictable behavior.
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I'm probably going to learn about the double pendulum in a few weeks, however I have a question that I can't get rid off from my head.
Is there a time (I imagine it to be very large) where the pendulum reach the initial position/configuration? In another words, a time where it moves as it has moved. Maybe we can call this a period, but I'm not really sure.
If I remember well, Poincaré's recurrence theorem implies the existence of such a time.

Mathematically I must have the motion equation under my eyes and set t=0. I do the same but setting t=t_1. And lastly I equal both equation and I solve for t_1. I'm guessing it's very hard to solve for t_1 since I never heard of a period of a double pendulum.
Do someone has something to say?
 
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In general, no. A double pendulum is a chaotic system and will not generally return to the same configuration as before. Also, you can usually only solve the equations of motion numerically and they are numerically unstable over long periods of time.
 
DaleSpam said:
In general, no. A double pendulum is a chaotic system and will not generally return to the same configuration as before. Also, you can usually only solve the equations of motion numerically and they are numerically unstable over long periods of time.

Ok thanks a lot for the information.
 
A double pendulum executes simple harmonic motion (two normal modes) when displacements from equilibrium are small. However, when large displacements are imposed, the non-linear system becomes dramatically chaotic in its motion and demonstrates that deterministic systems are not necessarily predictable.

http://www.fas.harvard.edu/~scdiroff/lds/MathamaticalTopics/ChaoticPendulum/ChaoticPendulum002.gif
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