>[!abstract] >Certain dynamical systems will, after a sufficiently long but finite time, return to a state arbitrarily close to (for continuous state systems), or exactly the same as (for discrete state systems), their initial state. The *Poincaré recurrence time* is the length of time elapsed until the recurrence (Wikipedia, 2025). >[!related] >- **North** (upstream): [[Ergodic theory]] >- **West** (similar): [[Boltzmann’s H-theorem paradoxes]], [[Buddhist temporal cosmology]] >- **East** (different): [[Second law of thermodynamics]] >- **South** (downstream): [[Recurrence time]]