Looking for a million-dollar pet? This poor vector field has been missing for years! The Navier-Stokes equation is desperately searching for its analytical solution—a mathematical unicorn that's "globally smooth," "divergence-free," and might not even exist (talk about an existential crisis).
The title "Sometimes He Answers To ∇×𝐮=𝟎" is basically saying our missing solution occasionally responds to "curl-free," which is like saying your runaway cat sometimes comes when you shake the treat bag.
Mathematicians have been hunting this solution for decades—it's literally one of the Millennium Prize Problems with a cool million attached. Finding it would be like discovering your missing sock AND winning the lottery simultaneously.