If you’ve ever whacked the bottom of a ketchup bottle to get that tasty tomato goop flowing, you’ve put some serious physics to work. Ketchup is a non-Newtonian fluid. So are toothpaste, yogurt, ...

Viscosity is one of the most fundamental physical properties used to describe how materials flow. It governs the movement of liquids, molten rocks and even slowly deforming regions deep inside the ...