  Lower bounds on fluctuations of thermodynamic currents depend on the nature
of time: discrete or continuous. To understand the physical reason, we compare
current fluctuations in discrete-time Markov chains and continuous-time master
equations. We prove that current fluctuations in the master equations are
always more likely, due to random timings of transitions. This comparison leads
to a mapping of the moments of a current between discrete and continuous time.
We exploit this mapping to obtain new uncertainty bounds. Our results reduce
the quests for uncertainty bounds in discrete and continuous time to a single
problem.
