Least dense solid

The world's least dense solid is a graphene aerogel with a density of just 0.16 mg/cm³; produced by a research team from the Department of Polymer Science and Engineering lab at Zhejiang University, China, headed up by Professor Gao Chao (China). The material was announced in Nature magazine on 27 February 2013.

To create the aerogel, Chao and his team "freeze-dried solutions of carbon nanotubes and large sheets of graphene oxide, and then chemically removed oxygen to leave a conductive, elastic, solid foam". Aerogel is lighter than air itself (1.2 mg/cm³, 0.3 grains/inch³) and is virtually invisible to the untrained eye.