Global regularity for Navier-Stokes equations is difficult to prove because supercriticality at small scales causes nonlinear transport terms to dominate dissipation terms, making it unpredictable.

“So Navis Stokes is what's called supercritical. So at at smaller and smaller scales, the transport terms are much stronger than the viscosity terms. So the viscosity are the things that calm things down.”

The mathematical model of Navier-Stokes equations is not fully understood, leaving uncertainty about whether it implies infinite energy density.

“the theoretical understanding of these equations is like worryingly thin in some respects where for example it's not entirely known if um it would imply that like you get an infinite concentration of energy at some point.”