  Theoretical and numerical studies of the Wilson flow in lattice QCD suggest
that the gauge field obtained at flow time t>0 is a smooth renormalized field.
The expectation values of local gauge-invariant expressions in this field are
thus well-defined physical quantities that probe the theory at length scales on
the order of sqrt(t). Moreover, by transforming the QCD functional integral to
an integral over the gauge field at a specified flow time, the emergence of the
topological (instanton) sectors in the continuum limit becomes transparent and
is seen to be caused by a dynamical effect that rapidly separates the sectors
when the lattice spacing is reduced from 0.1 fm to smaller values.
