Either nature or my brain or both do a wonderful job of clustering related things for me so that I often feel coming along many related things within a short time. Recently, I read Stuart L. Pimm‘s wonderful The World According to Pimm: a Scientist Audits the Earth. It contains the following sentence:
« Robert Colwell, an ecologist from the University of Connecticut, and I were sitting in a bar drinking Antarctica and excitedly drawing lines on paper napkins, the preferred medium of serious scientific discourse worldwide. »
Shortly afterwards, I learned about the blog What’s on my blackboard? showing people’s blackboards (or whiteboards) which are often stunning.
Hence my question: what’s on your napkin? I dare you: grab your smartphones and share images of your napkins full of scientific sketches and/or formulas!
Luke Oeding (Auburn University) was so good as to donate something that is almost a mathematical napkin:
He prepared this picture for a 5 minute postdoc talk at MSRI. It shows a day in the life of J. J. Sylvester‘s cat Kappa who likes cubes. Sylvester conjectured and Clebsch proved that a generic quaternary cubic can be written as a sum of five cubes of linear forms. Sylvester’s pentahedron gave a way to find the linear forms, but Kappa (the Koszul flattening matrix called Kappa in this paper) has a new algebraic method to find the linear forms.