A 3D shape with all straight edges and flat faces is a polyhedron. Other 3D shapes with least one curved surface are not polyhedra. A 3D shape with regular polygonal faces, meeting at equal angles, is ...

The second law of thermodynamics says that entropy may only ever increase during the conversion of one physical state into another. Finding an analogous quantity to characterize the conversion of ...

Whether erosion is accelerating or decelerating along Arctic rivers has been unclear, but each trend has distinct implications for the vast amount of carbon stored in permanently frozen soils. Now, ...