Materials shape human progress—think Stone Age or Bronze Age. The 21st century has been referred to as the molecular age, a time when scientists are beginning to manipulate materials at the atomic level to create new substances with astounding properties.

Taking a step in that direction, Jens Bauer, at the Karlsruhe Institute of Technology (KIT), and his colleagues have developed a bone-like material that is less dense than water but as strong as some forms of steel....