After briefly reviewing the recent results on the partial regularity for the hyperdissipative Navier-Stokes equations, we discuss the gap between the viscous systems and the non-viscous systems in terms of the issue of regularity/singularity. Inviscid limit itself is considered as an example of the bridge over the spectrum of viscosity. Zoom link: https://snu-ac-kr.zoom.us/j/4020312420