I Time Reversal Breaking in Classical Systems

AI Thread Summary
Examples of classical systems lacking time reversal symmetry include chaotic systems and those with friction, such as a damped pendulum. Non-reciprocal optics and electromagnetic nonreciprocity are also cited as relevant examples. Systems that experience loss inherently exhibit time-reversal asymmetry. The discussion raises questions about the effects of time reversal on closed systems under external magnetic fields. Overall, the exploration highlights the complexities of time reversal in classical physics.
hokhani
Messages
561
Reaction score
18
TL;DR 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.
 
Physics news on Phys.org
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.
 
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##
 
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.
 
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?
 
Thread 'Gauss' law seems to imply instantaneous electric field'

Thread 'Gauss' law seems to imply instantaneous electric field'

Imagine a charged sphere at the origin connected through an open switch to a vertical grounded wire. We wish to find an expression for the horizontal component of the electric field at a distance ##\mathbf{r}## from the sphere as it discharges. By using the Lorenz gauge condition: $$\nabla \cdot \mathbf{A} + \frac{1}{c^2}\frac{\partial \phi}{\partial t}=0\tag{1}$$ we find the following retarded solutions to the Maxwell equations If we assume that...
View full post »

Thread 'Off resonance driving of a MW/RF cavity'

Hello! Let's say I have a cavity resonant at 10 GHz with a Q factor of 1000. Given the Lorentzian shape of the cavity, I can also drive the cavity at, say 100 MHz. Of course the response will be very very weak, but non-zero given that the Loretzian shape never really reaches zero. I am trying to understand how are the magnetic and electric field distributions of the field at 100 MHz relative to the ones at 10 GHz? In particular, if inside the cavity I have some structure, such as 2 plates...
View full post »

Similar threads

I Time Reversal Symmetry in Classical Physics
Replies
11
Views
3K
B If gravity was a force wouldn't going back in time cause us to float?
Replies
13
Views
2K
I How can a process be isentropic but not reversible or adiobatic?
Replies
2
Views
3K
I Adiabatic irreversible process vs adiabatic reversible
Replies
1
Views
1K
I Physical reality of nontrivial loops in SO(3)
Replies
6
Views
2K
Irreversible quasi-static processes?
Replies
21
Views
3K
I Feynman's reversible and irreversible machines
Replies
5
Views
5K
I The relationship between reversible and irreversible processes
Replies
5
Views
2K
I Direction of time-evolution in time reversed wave functions
Replies
12
Views
409
Equations of State in Modern Classical Physics (Thorne/Blandford)
Replies
7
Views
2K

Hot Threads

Recent Insights

Back
Top