Beat of a current

Understand

The fluctuation relation, a milestone of modern thermodynamics, is only established when a set of fundamental currents can be measured.

• Here we prove that it also holds for systems with hidden transitions if observations are carried ``at their own beat,'' that is, by stopping the experiment after a fixed number of visible transitions, rather than the elapse of an external clock time.
• This suggests that thermodynamic symmetries are more resistant to the loss of information when described in the space of transitions.