While we’re on the subject of paper…
A fun story just came out in Physical Review Focus on origami. Well, not quite traditional origami.
If you wanted to make a box out of paper you start with a flat sheet and make a number of folds. BUT, if you want to make a millimeter-sized box or a micro-sized box you’ll need some tiny fingers…or a drop of water.
Researchers from the Institute of Industrial Physics and Chemistry in Paris used surface tension to turn flat, rubbery, millimeter-sized membranes into spheres, boxes, and pyramids.
They placed a drop of water on a membrane, making sure that it touched the corners of the surface. Then, as the drop evaporated, the sides of the membrane were pulled up due to surface tension. The shapes they got depended on the thickness of the membrane and its shape. Awesome!
Check out the more detailed story at Physical Review Focus and the accompanying movie.