Five years ago, Ellingsen had challenged accepted knowledge from 1887, armed with a pen and paper, and won.
For like so many accepted facts, this turns out to be wrong, or at least not always the case.
"It took the genius of people like Cauchy, Poisson and Kelvin to solve these wave problems for the first time, even for the simplest case of still water without currents.
If you throw a pebble in a lake on a peaceful summer's day, the wave pattern will be perfect, concentric circles.
Ellingsen also predicted this, expanding Cauchy and Poisson's theory from 1815.
Looking at them later, the rings looked oblong to me, and I got pretty excited.