Yesterday we fell asleep in the shade of a plane tree after tracing the branches that wound erratically up into a canopy of green. It was fun randomly popping up in random universities and having food in random university cafeterias.
Today somehow we decided to learn a bit of quantum stuff. Sorry, we didn't get the name of the stuff. As we don't have enough time, we'll just say that we saw a lot of linear algebra and tensors. We hand-multiplied some 4 x 4 matrices for fun, well, more precisely, for confirmation that we understood certain concepts.