A clock's precision is set fundamentally by how often it ticks
Kacper Prech, Gabriel Landi, Patrick Potts, Mark Mitchison and co-authors solved the problem of optimal time estimation from a classical Markovian jump process in the long-time limit.
They derived a tight upper bound on the precision of any time estimate, controlled by the mean residual time — the expected wait until the next observed jump. As a corollary they obtained a universal bound on the signal-to-noise ratio of arbitrary currents and counting observables in a steady state, provably tighter than the kinetic uncertainty relation, and explicitly constructed the observables that saturate it.
The result sharpens thermodynamic-uncertainty-style limits that tie precision to entropy production, of direct relevance to nanoscale clocks and molecular machines.