Does the Hamilton-Jacobi equation exist for chaotic systems?

  • #1
andresB
626
374
TL;DR Summary
Does the Hamilton-Jacobi equation exist for chaotic systems?
Given a Hamiltonian ##H(\mathbf{q},\mathbf{p})##, in the time-independent Hamilton-Jacobi approach we look for a canonical transformation ##(\mathbf{q},\mathbf{p})\rightarrow(\mathbf{Q},\mathbf{P})## such that the new Hamiltonian is one of the new momenta $$H(\mathbf{q},\mathbf{p})=K(\mathbf{Q},\mathbf{P})=P_{1}=E.$$
If such transformation exists, all the momenta ##\mathbf{P}## are constant of the motion. And, since the transformation is canonical, we will have n constant of the motion in involution, i.e., ##\left\{ P_{i},P_{j}\right\} =0.## But this seems to be the requirement of the Liouville theorem for integrability. Chaotic systems don't have that many constants of motion in involution.
This seems to imply that the Hamilton-Jacobi equations cannot be even written for chaotic systems, so my reasoning has to be wrong somewhere. Where?
 
Last edited by a moderator:
Physics news on Phys.org
  • #2
andresB said:
TL;DR Summary: Does the Hamilton-Jacobi equation exist for chaotic systems?

Given a Hamiltonian H(q,p), in the time-independent Hamilton-Jacobi approach we look for a canonical transformation (q,p)→(Q,P) such that the new Hamiltonian is one of the new momenta H(q,p)=K(Q,P)=P1=E.
If such transformation exists, all the momenta P are constant o
Such a transformation exists locally outside an equilibrium. The set where this transformation is defined is not invariant. The system comes and goes away from there, while a dynamical chaos appears in invariant sets.
 
Last edited:
  • #3
wrobel said:
Such a transformation exists locally outside an equilibrium. The set where this transformation is defined is not invariant. The system comes and goes away from there, while a dynamical chaos appears in invariant sets.

Ok, I suspected the issue had to do with the new momenta not being defined globally.

Yet, I'm not sure I understand your answer. Can you give more details or point to a source with an example?
 
  • #4
A dynamical chaos is an informal concept which expresses a complex of very different effects. The common feature for all these effects is a complicated behavior of trajectories of a dynamical system. Every time, one should specify what he means by saying “dynamical chaos”. For example, in Hamiltonian systems, ergodicity or separatrix splitting are commonly considered as a dynamical chaos, but there are a lot of other chaotic effects. Real life examples are really hard.
See for example this https://link.springer.com/book/10.1007/978-3-642-03028-4
or start from this https://www.mat.univie.ac.at/~gerald/ftp/book-ode/ode.pdf

UPD

Dissipative systems commonly have attractors. If an attractor is of complicated geometry, say has a fractional dimension, then trajectories which wind up on the attractor replicate its geometry and become complicated. That is another chaotic effect.
 
Last edited:
  • Informative
  • Like
Likes andresB and vanhees71
  • #5
Fascinating and frustrating at the same time.

wrobel said:

My doubts started by studyng perturbation theory. In the book Canonical Perturbation Theories Degenerate Systems and Resonance, I find the following
1691594084323.png


The usual books in analytical mechanics don't deal with this.
 

1. What is the Hamilton-Jacobi equation?

The Hamilton-Jacobi equation is a mathematical formula used in classical mechanics to describe the evolution of a system over time. It is based on the principle of least action and is used to determine the path of a particle or system from one point to another.

2. Can the Hamilton-Jacobi equation be applied to chaotic systems?

Yes, the Hamilton-Jacobi equation can be applied to chaotic systems. However, it is often more difficult to solve for chaotic systems due to their unpredictable and complex nature.

3. How does the Hamilton-Jacobi equation differ from other equations used in physics?

The Hamilton-Jacobi equation differs from other equations used in physics because it is a partial differential equation that describes the time evolution of a system, rather than just the position or momentum of a particle. It is also based on the principle of least action, which is not used in other equations.

4. Is the Hamilton-Jacobi equation a complete description of a chaotic system?

No, the Hamilton-Jacobi equation is not a complete description of a chaotic system. It is just one aspect of understanding the behavior of a chaotic system and must be used in conjunction with other mathematical tools and techniques to fully describe the system.

5. Are there any limitations to using the Hamilton-Jacobi equation for chaotic systems?

Yes, there are limitations to using the Hamilton-Jacobi equation for chaotic systems. It is often difficult to solve for chaotic systems and may not accurately predict the behavior of the system in all cases. Additionally, it may not be applicable to all types of chaotic systems, as some may exhibit behaviors that cannot be described by this equation.

Similar threads

Replies
3
Views
597
  • Introductory Physics Homework Help
Replies
5
Views
250
  • Classical Physics
Replies
4
Views
2K
  • Advanced Physics Homework Help
Replies
1
Views
693
Replies
1
Views
955
  • Introductory Physics Homework Help
Replies
3
Views
958
  • Classical Physics
Replies
6
Views
1K
Replies
4
Views
993
  • Classical Physics
Replies
2
Views
1K
  • Classical Physics
Replies
1
Views
1K
Back
Top