Experienced chefs know that to make a neat cut in a
boiled egg or a piece of cheese, a thin wire, or even a
fine piece of thread, can work better than a knife. But
even a blunt knife can cut soft solids well if it is rocked
back and forth while applying a gentle pressure. Understanding the balance of forces needed to make a clean cut
into deformable materials could be important for developing highly efficient techniques in industrial-scale food
processing, or new tools for cutting biological tissue for
analysis or during surgery. Writing in Physical Review
Letters[1], Etienne Reyssat, at Harvard University, and
colleagues provide an intriguing analysis of the cutting of
soft solids, applying a combination of theory and experiments to pinpoint the role played by shear in facilitating
the fracture of a highly deformable material.