Time Reversal Breaking in Classical Systems

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SUMMARY

Classical systems exhibit time reversal symmetry, but certain examples demonstrate time-reversal asymmetry. Chaotic systems, such as a damped pendulum described by the equation $$\ddot x+x=-\dot x$$, are not invariant under time reversal. Additionally, systems with loss, like non-reciprocal optics and electromagnetic nonreciprocity, also display time-reversal asymmetry. The discussion highlights the impact of external magnetic fields on closed systems and their relationship with time reversal.

PREREQUISITES
  • Understanding of classical mechanics and time reversal symmetry
  • Familiarity with chaotic systems and their behavior
  • Knowledge of non-reciprocal optics and electromagnetic nonreciprocity
  • Basic principles of entropy in classical physics
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  • Research the properties of chaotic systems in classical mechanics
  • Explore the principles of non-reciprocal optics
  • Investigate the effects of external magnetic fields on closed systems
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Physicists, students of classical mechanics, and researchers interested in the implications of time reversal symmetry in physical systems.

hokhani
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Classical systems without time reversal
I am looking for an example of a classical system without time reversal symmetry. I would appreciate any help.
 
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hokhani said:
Summary:: Classical systems without time reversal

I am looking for an example of a classical system without time reversal symmetry. I would appreciate any help.
Classical physics is symmetric under time reversal. Entropy is the only arrow that I know of classically.
 
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As example of classical systems that exhibit behavior that (in some practical sense at least) is not quite symmetric regarding time reversal I guess you could look at chaotic systems.
 
the banal pendulum with friction
$$\ddot x+x=-\dot x$$
is not invariant under the change ##t\mapsto -t##
 
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hokhani said:
Summary:: Classical systems without time reversal

I am looking for an example of a classical system without time reversal symmetry. I would appreciate any help.
Check out "non-reciprocal optics" or " electromagnetic nonreciprocity".

Any system with loss is also time-reversal asymmetric.
 
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Thank you all for the responses. How about a closed system which is under an external magnetic field? Does time reversal change also the external magnetic field or it only reverses the time in the closed system?
 

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