The thermodynamic uncertainty relation conjectured in 2015
 and proven using large deviation theory in 2016 
provides a universal constraint relating mean and dispersion
of any current in a driven system with the overall entropy
production. I will first introduce the basic concepts behind
this relation and then discuss a few of its applications.
Prominent amomg those are a universal model-free bound on
the efficiency of molecular motors  and insight into the
current debate whether or not heat engines can approach
Carnot efficiency at finite power . Stronger versions of
this bound require knowledge of the underlying topology and
driving affinities of the network .
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 T. R. Gingrich, et al, Phys. Rev. Lett. 116, 120601, 2016
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